urring mix of lithium isotopes. However, the supply of lithium is relatively limited with other applications such as Li-ion batteries increasing its demand.[citation needed] Several drawbacks are commonly attributed to D-T fusion power: 1. It produces substantial amounts of neutrons that result in induced radioactivity within the reactor structure.[6] 2. Only about 20% of the fusion energy yield appears in the form of charged particles (the rest neutrons), which limits the extent to which direct energy conversion techniques might be applied.[citation needed] 3. The use of D-T fusion power depends on lithium resources, which are less abundant than deuterium resources. However, lithium is relatively abundant on earth.[6] 4. It requires the handling of the radioisotope tritium. Similar to hydrogen, tritium is difficult to contain and may leak from reactors in some quantity. Some estimates suggest that this would represent a fairly large environmental release of radioactivity.[7] The neutron flux expected in a commercial D-T fusion reactor is about 100 times that of current fission power reactors, posing problems for material design. Design of suitable materials is under way but their actual use in a reactor is not proposed until the generation after ITER. After a single series of D-T tests at JET, the largest fusion reactor yet to use this fuel, the vacuum vessel was sufficiently radioactive that remote handling needed to be used for the year following the tests. In a production setting, the neutrons would be used to react with lithium in order to create more tritium. This also deposits the energy of the neutrons in the lithium, which would then be cooled to remove this energy and drive electrical production. This reaction protects the outer portions of the reactor from the neutron flux. Newer designs, the advanced tokamak in particular, also use lithium inside the reactor core as a key element of the design. The plasma interacts directly with the lithium, preventing a problem known as "recycling". The advantage of this layout was demonstrated in the Lithium Tokamak Experiment. [edit] D-D fuel cycle Though more difficult to facilitate than the deuterium-tritium reaction, fusion can also be achieved through the reaction of deuterium with itself. This reaction has two branches that occur with nearly equal probability: 2H + 2H → 3T + 1H → 3He + n The optimum energy for this reaction is 15 keV, only slightly higher than the optimum for the D-T reaction. The first branch does not produce neutrons, but it does produce tritium, so that a D-D reactor will not be completely tritium-free, even though it does not require an input of tritium or lithium. Most of the tritium produced will be burned before leaving the reactor, which reduces the tritium handling required, but also means that more neutrons are produced and that some of these are very energetic. The neutron from the second branch has an energy of only 2.45 MeV (0.393 pJ), whereas the neutron from the D-T reaction has an energy of 14.1 MeV (2.26 pJ), resulting in a wider range of isotope production and material damage. Assuming complete tritium burn-up, the reduction in the fraction of fusion energy carried by neutrons is only about 18%, so that the primary advantage of the D-D fuel cycle is that tritium breeding is not required. Other advantages are independence from limitations of lithium resources and a somewhat softer neutron spectrum. The price to pay compared to D-T is that the energy confinement (at a given pressure) must be 30 times better and the power produced (at a given pressure and volume) is 68 times less. [edit] D-3He fuel cycle A second-generation approach to controlled fusion power involves combining helium-3 (3He) and deuterium (2H). This reaction produces a helium-4 nucleus (4He) and a high-energy proton. As with the p-11B aneutronic fusion fuel cycle, most of the reaction energy is released as charged particles, reducing activation of the reactor housing and potentially allowing more efficient energy harvesting (via any of several speculative technologies). In practice, D-D side reactions produce a significant number of neutrons, resulting in p-11B being the preferred cycle for aneutronic fusion. [edit] p-11B fuel cycle If aneutronic fusion is the goal, then the most promising candidate may be the Hydrogen-1 (proton)/boron reaction: 1H + 11B → 3 4He Under reasonable assumptions, side reactions will result in about 0.1% of the fusion power being carried by neutrons.[8] At 123 keV, the optimum temperature for this reaction is nearly ten times higher than that for the pure hydrogen reactions, the energy confinement must be 500 times better than that required for the D-T reaction, and the power density will be 2500 times lower than for D-T. Since the confinement properties of conventional approaches to fusion such as the tokamak and laser pellet fusion are marginal, most proposals for aneutronic fusion are based on radically different confinement concepts, such as the Polywell and the Dense plasma focus. [edit] History of research [edit] Brief overview The idea of using human-initiated fusion reactions was first made practical for miliurring mix of lithium isotopes. However, the supply of lithium is relatively limited with other applications such as Li-ion batteries increasing its demand.[citation needed] Several drawbacks are commonly attributed to D-T fusion power: 1. It produces substantial amounts of neutrons that result in induced radioactivity within the reactor structure.[6] 2. Only about 20% of the fusion energy yield appears in the form of charged particles (the rest neutrons), which limits the extent to which direct energy conversion techniques might be applied.[citation needed] 3. The use of D-T fusion power depends on lithium resources, which are less abundant than deuterium resources. However, lithium is relatively abundant on earth.[6] 4. It requires the handling of the radioisotope tritium. Similar to hydrogen, tritium is difficult to contain and may leak from reactors in some quantity. Some estimates suggest that this would represent a fairly large environmental release of radioactivity.[7] The neutron flux expected in a commercial D-T fusion reactor is about 100 times that of current fission power reactors, posing problems for material design. Design of suitable materials is under way but their actual use in a reactor is not proposed until the generation after ITER. After a single series of D-T tests at JET, the largest fusion reactor yet to use this fuel, the vacuum vessel was sufficiently radioactive that remote handling needed to be used for the year following the tests. In a production setting, the neutrons would be used to react with lithium in order to create more tritium. This also deposits the energy of the neutrons in the lithium, which would then be cooled to remove this energy and drive electrical production. This reaction protects the outer portions of the reactor from the neutron flux. Newer designs, the advanced tokamak in particular, also use lithium inside the reactor core as a key element of the design. The plasma interacts directly with the lithium, preventing a problem known as "recycling". The advantage of this layout was demonstrated in the Lithium Tokamak Experiment. [edit] D-D fuel cycle Though more difficult to facilitate than the deuterium-tritium reaction, fusion can also be achieved through the reaction of deuterium with itself. This reaction has two branches that occur with nearly equal probability: 2H + 2H → 3T + 1H → 3He + n The optimum energy for this reaction is 15 keV, only slightly higher than the optimum for the D-T reaction. The first branch does not produce neutrons, but it does produce tritium, so that a D-D reactor will not be completely tritium-free, even though it does not require an input of tritium or lithium. Most of the tritium produced will be burned before leaving the reactor, which reduces the tritium handling required, but also means that more neutrons are produced and that some of these are very energetic. The neutron from the second branch has an energy of only 2.45 MeV (0.393 pJ), whereas the neutron from the D-T reaction has an energy of 14.1 MeV (2.26 pJ), resulting in a wider range of isotope production and material damage. Assuming complete tritium burn-up, the reduction in the fraction of fusion energy carried by neutrons is only about 18%, so that the primary advantage of the D-D fuel cycle is that tritium breeding is not required. Other advantages are independence from limitations of lithium resources and a somewhat softer neutron spectrum. The price to pay compared to D-T is that the energy confinement (at a given pressure) must be 30 times better and the power produced (at a given pressure and volume) is 68 times less. [edit] D-3He fuel cycle A second-generation approach to controlled fusion power involves combining helium-3 (3He) and deuterium (2H). This reaction produces a helium-4 nucleus (4He) and a high-energy proton. As with the p-11B aneutronic fusion fuel cycle, most of the reaction energy is released as charged particles, reducing activation of the reactor housing and potentially allowing more efficient energy harvesting (via any of several speculative technologies). In practice, D-D side reactions produce a significant number of neutrons, resulting in p-11B being the preferred cycle for aneutronic fusion. [edit] p-11B fuel cycle If aneutronic fusion is the goal, then the most promising candidate may be the Hydrogen-1 (proton)/boron reaction: 1H + 11B → 3 4He Under reasonable assumptions, side reactions will result in about 0.1% of the fusion power being carried by neutrons.[8] At 123 keV, the optimum temperature for this reaction is nearly ten times higher than that for the pure hydrogen reactions, the energy confinement must be 500 times better than that required for the D-T reaction, and the power density will be 2500 times lower than for D-T. Since the confinement properties of conventional approaches to fusion such as the tokamak and laser pellet fusion are marginal, most proposals for aneutronic fusion are based on radically different confinement concepts, such as the Polywell and the Dense plasma focus. [edit] History of research [edit] Brief overview The idea of using human-initiated fusion reactions was first made practical for miliurring mix of lithium isotopes. However, the supply of lithium is relatively limited with other applications such as Li-ion batteries increasing its demand.[citation needed] Several drawbacks are commonly attributed to D-T fusion power: 1. It produces substantial amounts of neutrons that result in induced radioactivity within the reactor structure.[6] 2. Only about 20% of the fusion energy yield appears in the form of charged particles (the rest neutrons), which limits the extent to which direct energy conversion techniques might be applied.[citation needed] 3. The use of D-T fusion power depends on lithium resources, which are less abundant than deuterium resources. However, lithium is relatively abundant on earth.[6] 4. It requires the handling of the radioisotope tritium. Similar to hydrogen, tritium is difficult to contain and may leak from reactors in some quantity. Some estimates suggest that this would represent a fairly large environmental release of radioactivity.[7] The neutron flux expected in a commercial D-T fusion reactor is about 100 times that of current fission power reactors, posing problems for material design. Design of suitable materials is under way but their actual use in a reactor is not proposed until the generation after ITER. After a single series of D-T tests at JET, the largest fusion reactor yet to use this fuel, the vacuum vessel was sufficiently radioactive that remote handling needed to be used for the year following the tests. In a production setting, the neutrons would be used to react with lithium in order to create more tritium. This also deposits the energy of the neutrons in the lithium, which would then be cooled to remove this energy and drive electrical production. This reaction protects the outer portions of the reactor from the neutron flux. Newer designs, the advanced tokamak in particular, also use lithium inside the reactor core as a key element of the design. The plasma interacts directly with the lithium, preventing a problem known as "recycling". The advantage of this layout was demonstrated in the Lithium Tokamak Experiment. [edit] D-D fuel cycle Though more difficult to facilitate than the deuterium-tritium reaction, fusion can also be achieved through the reaction of deuterium with itself. This reaction has two branches that occur with nearly equal probability: 2H + 2H → 3T + 1H → 3He + n The optimum energy for this reaction is 15 keV, only slightly higher than the optimum for the D-T reaction. The first branch does not produce neutrons, but it does produce tritium, so that a D-D reactor will not be completely tritium-free, even though it does not require an input of tritium or lithium. Most of the tritium produced will be burned before leaving the reactor, which reduces the tritium handling required, but also means that more neutrons are produced and that some of these are very energetic. The neutron from the second branch has an energy of only 2.45 MeV (0.393 pJ), whereas the neutron from the D-T reaction has an energy of 14.1 MeV (2.26 pJ), resulting in a wider range of isotope production and material damage. Assuming complete tritium burn-up, the reduction in the fraction of fusion energy carried by neutrons is only about 18%, so that the primary advantage of the D-D fuel cycle is that tritium breeding is not required. Other advantages are independence from limitations of lithium resources and a somewhat softer neutron spectrum. The price to pay compared to D-T is that the energy confinement (at a given pressure) must be 30 times better and the power produced (at a given pressure and volume) is 68 times less. [edit] D-3He fuel cycle A second-generation approach to controlled fusion power involves combining helium-3 (3He) and deuterium (2H). This reaction produces a helium-4 nucleus (4He) and a high-energy proton. As with the p-11B aneutronic fusion fuel cycle, most of the reaction energy is released as charged particles, reducing activation of the reactor housing and potentially allowing more efficient energy harvesting (via any of several speculative technologies). In practice, D-D side reactions produce a significant number of neutrons, resulting in p-11B being the preferred cycle for aneutronic fusion. [edit] p-11B fuel cycle If aneutronic fusion is the goal, then the most promising candidate may be the Hydrogen-1 (proton)/boron reaction: 1H + 11B → 3 4He Under reasonable assumptions, side reactions will result in about 0.1% of the fusion power being carried by neutrons.[8] At 123 keV, the optimum temperature for this reaction is nearly ten times higher than that for the pure hydrogen reactions, the energy confinement must be 500 times better than that required for the D-T reaction, and the power density will be 2500 times lower than for D-T. Since the confinement properties of conventional approaches to fusion such as the tokamak and laser pellet fusion are marginal, most proposals for aneutronic fusion are based on radically different confinement concepts, such as the Polywell and the Dense plasma focus. [edit] History of research [edit] Brief overview The idea of using human-initiated fusion reactions was first made practical for miliurring mix of lithium isotopes. However, the supply of lithium is relatively limited with other applications such as Li-ion batteries increasing its demand.[citation needed] Several drawbacks are commonly attributed to D-T fusion power: 1. It produces substantial amounts of neutrons that result in induced radioactivity within the reactor structure.[6] 2. Only about 20% of the fusion energy yield appears in the form of charged particles (the rest neutrons), which limits the extent to which direct energy conversion techniques might be applied.[citation needed] 3. The use of D-T fusion power depends on lithium resources, which are less abundant than deuterium resources. However, lithium is relatively abundant on earth.[6] 4. It requires the handling of the radioisotope tritium. Similar to hydrogen, tritium is difficult to contain and may leak from reactors in some quantity. Some estimates suggest that this would represent a fairly large environmental release of radioactivity.[7] The neutron flux expected in a commercial D-T fusion reactor is about 100 times that of current fission power reactors, posing problems for material design. Design of suitable materials is under way but their actual use in a reactor is not proposed until the generation after ITER. After a single series of D-T tests at JET, the largest fusion reactor yet to use this fuel, the vacuum vessel was sufficiently radioactive that remote handling needed to be used for the year following the tests. In a production setting, the neutrons would be used to react with lithium in order to create more tritium. This also deposits the energy of the neutrons in the lithium, which would then be cooled to remove this energy and drive electrical production. This reaction protects the outer portions of the reactor from the neutron flux. Newer designs, the advanced tokamak in particular, also use lithium inside the reactor core as a key element of the design. The plasma interacts directly with the lithium, preventing a problem known as "recycling". The advantage of this layout was demonstrated in the Lithium Tokamak Experiment. [edit] D-D fuel cycle Though more difficult to facilitate than the deuterium-tritium reaction, fusion can also be achieved through the reaction of deuterium with itself. This reaction has two branches that occur with nearly equal probability: 2H + 2H → 3T + 1H → 3He + n The optimum energy for this reaction is 15 keV, only slightly higher than the optimum for the D-T reaction. The first branch does not produce neutrons, but it does produce tritium, so that a D-D reactor will not be completely tritium-free, even though it does not require an input of tritium or lithium. Most of the tritium produced will be burned before leaving the reactor, which reduces the tritium handling required, but also means that more neutrons are produced and that some of these are very energetic. The neutron from the second branch has an energy of only 2.45 MeV (0.393 pJ), whereas the neutron from the D-T reaction has an energy of 14.1 MeV (2.26 pJ), resulting in a wider range of isotope production and material damage. Assuming complete tritium burn-up, the reduction in the fraction of fusion energy carried by neutrons is only about 18%, so that the primary advantage of the D-D fuel cycle is that tritium breeding is not required. Other advantages are independence from limitations of lithium resources and a somewhat softer neutron spectrum. The price to pay compared to D-T is that the energy confinement (at a given pressure) must be 30 times better and the power produced (at a given pressure and volume) is 68 times less. [edit] D-3He fuel cycle A second-generation approach to controlled fusion power involves combining helium-3 (3He) and deuterium (2H). This reaction produces a helium-4 nucleus (4He) and a high-energy proton. As with the p-11B aneutronic fusion fuel cycle, most of the reaction energy is released as charged particles, reducing activation of the reactor housing and potentially allowing more efficient energy harvesting (via any of several speculative technologies). In practice, D-D side reactions produce a significant number of neutrons, resulting in p-11B being the preferred cycle for aneutronic fusion. [edit] p-11B fuel cycle If aneutronic fusion is the goal, then the most promising candidate may be the Hydrogen-1 (proton)/boron reaction: 1H + 11B → 3 4He Under reasonable assumptions, side reactions will result in about 0.1% of the fusion power being carried by neutrons.[8] At 123 keV, the optimum temperature for this reaction is nearly ten times higher than that for the pure hydrogen reactions, the energy confinement must be 500 times better than that required for the D-T reaction, and the power density will be 2500 times lower than for D-T. Since the confinement properties of conventional approaches to fusion such as the tokamak and laser pellet fusion are marginal, most proposals for aneutronic fusion are based on radically different confinement concepts, such as the Polywell and the Dense plasma focus. [edit] History of research [edit] Brief overview The idea of using human-initiated fusion reactions was first made practical for miliurring mix of lithium isotopes. However, the supply of lithium is relatively limited with other applications such as Li-ion batteries increasing its demand.[citation needed] Several drawbacks are commonly attributed to D-T fusion power: 1. It produces substantial amounts of neutrons that result in induced radioactivity within the reactor structure.[6] 2. Only about 20% of the fusion energy yield appears in the form of charged particles (the rest neutrons), which limits the extent to which direct energy conversion techniques might be applied.[citation needed] 3. The use of D-T fusion power depends on lithium resources, which are less abundant than deuterium resources. However, lithium is relatively abundant on earth.[6] 4. It requires the handling of the radioisotope tritium. Similar to hydrogen, tritium is difficult to contain and may leak from reactors in some quantity. Some estimates suggest that this would represent a fairly large environmental release of radioactivity.[7] The neutron flux expected in a commercial D-T fusion reactor is about 100 times that of current fission power reactors, posing problems for material design. Design of suitable materials is under way but their actual use in a reactor is not proposed until the generation after ITER. After a single series of D-T tests at JET, the largest fusion reactor yet to use this fuel, the vacuum vessel was sufficiently radioactive that remote handling needed to be used for the year following the tests. In a production setting, the neutrons would be used to react with lithium in order to create more tritium. This also deposits the energy of the neutrons in the lithium, which would then be cooled to remove this energy and drive electrical production. This reaction protects the outer portions of the reactor from the neutron flux. Newer designs, the advanced tokamak in particular, also use lithium inside the reactor core as a key element of the design. The plasma interacts directly with the lithium, preventing a problem known as "recycling". The advantage of this layout was demonstrated in the Lithium Tokamak Experiment. [edit] D-D fuel cycle Though more difficult to facilitate than the deuterium-tritium reaction, fusion can also be achieved through the reaction of deuterium with itself. This reaction has two branches that occur with nearly equal probability: 2H + 2H → 3T + 1H → 3He + n The optimum energy for this reaction is 15 keV, only slightly higher than the optimum for the D-T reaction. The first branch does not produce neutrons, but it does produce tritium, so that a D-D reactor will not be completely tritium-free, even though it does not require an input of tritium or lithium. Most of the tritium produced will be burned before leaving the reactor, which reduces the tritium handling required, but also means that more neutrons are produced and that some of these are very energetic. The neutron from the second branch has an energy of only 2.45 MeV (0.393 pJ), whereas the neutron from the D-T reaction has an energy of 14.1 MeV (2.26 pJ), resulting in a wider range of isotope production and material damage. Assuming complete tritium burn-up, the reduction in the fraction of fusion energy carried by neutrons is only about 18%, so that the primary advantage of the D-D fuel cycle is that tritium breeding is not required. Other advantages are independence from limitations of lithium resources and a somewhat softer neutron spectrum. The price to pay compared to D-T is that the energy confinement (at a given pressure) must be 30 times better and the power produced (at a given pressure and volume) is 68 times less. [edit] D-3He fuel cycle A second-generation approach to controlled fusion power involves combining helium-3 (3He) and deuterium (2H). This reaction produces a helium-4 nucleus (4He) and a high-energy proton. As with the p-11B aneutronic fusion fuel cycle, most of the reaction energy is released as charged particles, reducing activation of the reactor housing and potentially allowing more efficient energy harvesting (via any of several speculative technologies). In practice, D-D side reactions produce a significant number of neutrons, resulting in p-11B being the preferred cycle for aneutronic fusion. [edit] p-11B fuel cycle If aneutronic fusion is the goal, then the most promising candidate may be the Hydrogen-1 (proton)/boron reaction: 1H + 11B → 3 4He Under reasonable assumptions, side reactions will result in about 0.1% of the fusion power being carried by neutrons.[8] At 123 keV, the optimum temperature for this reaction is nearly ten times higher than that for the pure hydrogen reactions, the energy confinement must be 500 times better than that required for the D-T reaction, and the power density will be 2500 times lower than for D-T. Since the confinement properties of conventional approaches to fusion such as the tokamak and laser pellet fusion are marginal, most proposals for aneutronic fusion are based on radically different confinement concepts, such as the Polywell and the Dense plasma focus. [edit] History of research [edit] Brief overview The idea of using human-initiated fusion reactions was first made practical for miliD-3He fuel cycle A second-generation approach to controlled fusion power involves combining helium-3 (3He) and deuterium (2H). This reaction produces a helium-4 nucleus (4He) and a high-energy proton. As with the p-11B aneutronic fusion fuel cycle, most of the reaction energy is released as charged particles, reducing activation of the reactor housing and potentially allowing more efficient energy harvesting (via any of several speculative technologies). In practice, D-D side reactions produce a significant number of neutrons, resulting in p-11B being the preferred cycle for aneutronic fusion. [edit] p-11B fuel cycle If aneutronic fusion is the goal, then the most promising candidate may be the Hydrogen-1 (proton)/boron reaction: 1H + 11B → 3 4He Under reasonable assumptions, side reactions will result in about 0.1% of the fusion power being carried by neutrons.[8] At 123 keV, the optimum temperature for this reaction is nearly ten times higher than that for the pure hydrogen reactions, the energy confinement must be 500 times better than that required for the D-T reaction, and the power density will be 2500 times lower than for D-T. Since the confinement properties of conventional approaches to fusion such as the tokamak and laser pellet fusion are marginal, most proposals for aneutronic fusion are based on radically different confinement concepts, such as the Polywell and the Dense plasma focus. [edit] History of research [edit] Brief overview The idea of using human-initiated fusion reactions was first made practical for military purposes in nuclear weapons. In a hydrogen bomb, the energy released by a fission weapon is used to compress and heat fusion fuel, beginning a fusion reaction that releases a large amount of neutrons that increases the rate of fission. The first fission-fusion-fission-based weapons released some 500 times more energy than early fission weapons. Attempts at controlling fusion had already started by this point. Registration of the first patent related to a fusion reactor[9] by the United Kingdom Atomic Energy Authority, the inventors being Sir George Paget Thomson and Moses Blackman, dates back to 1946. This was the first detailed examination of the pinch concept, and small efforts to experiment with the pinch concept started at several sites in the UK. Around the same time, an expatriate German proposed the Huemul Project in Argentina, announcing positive results in 1951. Although these results turned out to be false, it sparked off intense interest around the world. The UK pinch programs were greatly expanded, culminating in the ZETA and Sceptre devices. In the US, pinch experiments like those in the UK started at the Los Alamos National Laboratory. Similar devices were built in the USSR after data on the UK program was passed to them by Klaus Fuchs. At Princeton University a new approach developed as the stellarator, and the research establishment formed there continues to this day as the Princeton Plasma Physics Laboratory. Not to be outdone, Lawrence Livermore National Laboratory entered the field with their own variation, the magnetic mirror. These three groups have remained the primary developers of fusion research in the US to this day. In the time since these early experiments, two new approaches developed that have since come to dominate fusion research. The first was the tokamak approach developed in the Soviet Union, which combined features of the stellarator and pinch to produce a device that dramatically outperformed either. The majority of magnetic fusion research to this day has followed the tokamak approach. In the late 1960s the concept of "mechanical" fusion through the use of lasers was developed in the US, and Lawrence Livermore switched their attention from mirrors to lasers over time. Civilian applications are still being developed. Although it took less than ten years for fission to go from military applications to civilian fission energy production,[10] it has been very different in the fusion energy field; more than fifty years have already passed since the first fusion reaction took place[11] and sixty years since the first attempts to produce controlled fusion power, without any commercial fusion energy production plant coming into operation. [edit] Magnetic containment [edit] Pinch devices A "wires array" used in Z-pinch confinement, during the building process A major area of study in early fusion power research is the "pinch" concept. Pinch is based on the fact the plasmas are electrically conducting. By running a current through the plasma, a magnetic field will be generated around the plasma. This field will, according to Lenz's law, create an inward directed force that causes the plasma to collapse inward, raising its density. Denser plasmas generate denser magnetic fields, increasing the inward force, leading to a chain reaction. If the conditions are correct, this can lead to the densities and temperatures needed for fusion. The trick is getting the current into the plasma; this is solved by inducing the current from an external magnet, which also produces the external field the internal field acts against. Pinch was first developed in the UK in the immediate post-war era. Starting in 1947 small experiments were carried out and plans were laid to build a much larger machine. When the Huemul results hit the news, James L. Tuck, a UK physicist working at Los Alamos, introduced the pinch concept in the US and produced a series of machines known as the Perhapsatron. In the Soviet Union, a series of similar machines were being built, unknown in the west. All of these devices quickly demonstrated a series of instabilities in the fusion when the pinch was applied, which broke up the plasma column long before it reached the densities and temperatures needed for fusion. In 1953 Tuck and others suggested a number of solutions to these problems. The largest "classic" pinch device was the ZETA, including all of these upgrades, starting operations in the UK in 1957. In early 1958 John Cockcroft announced that fusion had been achieved in the ZETA, an announcement that made headlines around the world. When physicists in the US expressed concerns about the claims they were initially dismissed. However, US experiments demonstrated the same neutrons, although meD-3He fuel cycle A second-generation approach to controlled fusion power involves combining helium-3 (3He) and deuterium (2H). This reaction produces a helium-4 nucleus (4He) and a high-energy proton. As with the p-11B aneutronic fusion fuel cycle, most of the reaction energy is released as charged particles, reducing activation of the reactor housing and potentially allowing more efficient energy harvesting (via any of several speculative technologies). In practice, D-D side reactions produce a significant number of neutrons, resulting in p-11B being the preferred cycle for aneutronic fusion. [edit] p-11B fuel cycle If aneutronic fusion is the goal, then the most promising candidate may be the Hydrogen-1 (proton)/boron reaction: 1H + 11B → 3 4He Under reasonable assumptions, side reactions will result in about 0.1% of the fusion power being carried by neutrons.[8] At 123 keV, the optimum temperature for this reaction is nearly ten times higher than that for the pure hydrogen reactions, the energy confinement must be 500 times better than that required for the D-T reaction, and the power density will be 2500 times lower than for D-T. Since the confinement properties of conventional approaches to fusion such as the tokamak and laser pellet fusion are marginal, most proposals for aneutronic fusion are based on radically different confinement concepts, such as the Polywell and the Dense plasma focus. [edit] History of research [edit] Brief overview The idea of using human-initiated fusion reactions was first made practical for military purposes in nuclear weapons. In a hydrogen bomb, the energy released by a fission weapon is used to compress and heat fusion fuel, beginning a fusion reaction that releases a large amount of neutrons that increases the rate of fission. The first fission-fusion-fission-based weapons released some 500 times more energy than early fission weapons. Attempts at controlling fusion had already started by this point. Registration of the first patent related to a fusion reactor[9] by the United Kingdom Atomic Energy Authority, the inventors being Sir George Paget Thomson and Moses Blackman, dates back to 1946. This was the first detailed examination of the pinch concept, and small efforts to experiment with the pinch concept started at several sites in the UK. Around the same time, an expatriate German proposed the Huemul Project in Argentina, announcing positive results in 1951. Although these results turned out to be false, it sparked off intense interest around the world. The UK pinch programs were greatly expanded, culminating in the ZETA and Sceptre devices. In the US, pinch experiments like those in the UK started at the Los Alamos National Laboratory. Similar devices were built in the USSR after data on the UK program was passed to them by Klaus Fuchs. At Princeton University a new approach developed as the stellarator, and the research establishment formed there continues to this day as the Princeton Plasma Physics Laboratory. Not to be outdone, Lawrence Livermore National Laboratory entered the field with their own variation, the magnetic mirror. These three groups have remained the primary developers of fusion research in the US to this day. In the time since these early experiments, two new approaches developed that have since come to dominate fusion research. The first was the tokamak approach developed in the Soviet Union, which combined features of the stellarator and pinch to produce a device that dramatically outperformed either. The majority of magnetic fusion research to this day has followed the tokamak approach. In the late 1960s the concept of "mechanical" fusion through the use of lasers was developed in the US, and Lawrence Livermore switched their attention from mirrors to lasers over time. Civilian applications are still being developed. Although it took less than ten years for fission to go from military applications to civilian fission energy production,[10] it has been very different in the fusion energy field; more than fifty years have already passed since the first fusion reaction took place[11] and sixty years since the first attempts to produce controlled fusion power, without any commercial fusion energy production plant coming into operation. [edit] Magnetic containment [edit] Pinch devices A "wires array" used in Z-pinch confinement, during the building process A major area of study in early fusion power research is the "pinch" concept. Pinch is based on the fact the plasmas are electrically conducting. By running a current through the plasma, a magnetic field will be generated around the plasma. This field will, according to Lenz's law, create an inward directed force that causes the plasma to collapse inward, raising its density. Denser plasmas generate denser magnetic fields, increasing the inward force, leading to a chain reaction. If the conditions are correct, this can lead to the densities and temperatures needed for fusion. The trick is getting the current into the plasma; this is solved by inducing the current from an external magnet, which also produces the external field the internal field acts against. Pinch was first developed in the UK in the immediate post-war era. Starting in 1947 small experiments were carried out and plans were laid to build a much larger machine. When the Huemul results hit the news, James L. Tuck, a UK physicist working at Los Alamos, introduced the pinch concept in the US and produced a series of machines known as the Perhapsatron. In the Soviet Union, a series of similar machines were being built, unknown in the west. All of these devices quickly demonstrated a series of instabilities in the fusion when the pinch was applied, which broke up the plasma column long before it reached the densities and temperatures needed for fusion. In 1953 Tuck and others suggested a number of solutions to these problems. The largest "classic" pinch device was the ZETA, including all of these upgrades, starting operations in the UK in 1957. In early 1958 John Cockcroft announced that fusion had been achieved in the ZETA, an announcement that made headlines around the world. When physicists in the US expressed concerns about the claims they were initially dismissed. However, US experiments demonstrated the same neutrons, although meD-3He fuel cycle A second-generation approach to controlled fusion power involves combining helium-3 (3He) and deuterium (2H). This reaction produces a helium-4 nucleus (4He) and a high-energy proton. As with the p-11B aneutronic fusion fuel cycle, most of the reaction energy is released as charged particles, reducing activation of the reactor housing and potentially allowing more efficient energy harvesting (via any of several speculative technologies). In practice, D-D side reactions produce a significant number of neutrons, resulting in p-11B being the preferred cycle for aneutronic fusion. [edit] p-11B fuel cycle If aneutronic fusion is the goal, then the most promising candidate may be the Hydrogen-1 (proton)/boron reaction: 1H + 11B → 3 4He Under reasonable assumptions, side reactions will result in about 0.1% of the fusion power being carried by neutrons.[8] At 123 keV, the optimum temperature for this reaction is nearly ten times higher than that for the pure hydrogen reactions, the energy confinement must be 500 times better than that required for the D-T reaction, and the power density will be 2500 times lower than for D-T. Since the confinement properties of conventional approaches to fusion such as the tokamak and laser pellet fusion are marginal, most proposals for aneutronic fusion are based on radically different confinement concepts, such as the Polywell and the Dense plasma focus. [edit] History of research [edit] Brief overview The idea of using human-initiated fusion reactions was first made practical for military purposes in nuclear weapons. In a hydrogen bomb, the energy released by a fission weapon is used to compress and heat fusion fuel, beginning a fusion reaction that releases a large amount of neutrons that increases the rate of fission. The first fission-fusion-fission-based weapons released some 500 times more energy than early fission weapons. Attempts at controlling fusion had already started by this point. Registration of the first patent related to a fusion reactor[9] by the United Kingdom Atomic Energy Authority, the inventors being Sir George Paget Thomson and Moses Blackman, dates back to 1946. This was the first detailed examination of the pinch concept, and small efforts to experiment with the pinch concept started at several sites in the UK. Around the same time, an expatriate German proposed the Huemul Project in Argentina, announcing positive results in 1951. Although these results turned out to be false, it sparked off intense interest around the world. The UK pinch programs were greatly expanded, culminating in the ZETA and Sceptre devices. In the US, pinch experiments like those in the UK started at the Los Alamos National Laboratory. Similar devices were built in the USSR after data on the UK program was passed to them by Klaus Fuchs. At Princeton University a new approach developed as the stellarator, and the research establishment formed there continues to this day as the Princeton Plasma Physics Laboratory. Not to be outdone, Lawrence Livermore National Laboratory entered the field with their own variation, the magnetic mirror. These three groups have remained the primary developers of fusion research in the US to this day. In the time since these early experiments, two new approaches developed that have since come to dominate fusion research. The first was the tokamak approach developed in the Soviet Union, which combined features of the stellarator and pinch to produce a device that dramatically outperformed either. The majority of magnetic fusion research to this day has followed the tokamak approach. In the late 1960s the concept of "mechanical" fusion through the use of lasers was developed in the US, and Lawrence Livermore switched their attention from mirrors to lasers over time. Civilian applications are still being developed. Although it took less than ten years for fission to go from military applications to civilian fission energy production,[10] it has been very different in the fusion energy field; more than fifty years have already passed since the first fusion reaction took place[11] and sixty years since the first attempts to produce controlled fusion power, without any commercial fusion energy production plant coming into operation. [edit] Magnetic containment [edit] Pinch devices A "wires array" used in Z-pinch confinement, during the building process A major area of study in early fusion power research is the "pinch" concept. Pinch is based on the fact the plasmas are electrically conducting. By running a current through the plasma, a magnetic field will be generated around the plasma. This field will, according to Lenz's law, create an inward directed force that causes the plasma to collapse inward, raising its density. Denser plasmas generate denser magnetic fields, increasing the inward force, leading to a chain reaction. If the conditions are correct, this can lead to the densities and temperatures needed for fusion. The trick is getting the current into the plasma; this is solved by inducing the current from an external magnet, which also produces the external field the internal field acts against. Pinch was first developed in the UK in the immediate post-war era. Starting in 1947 small experiments were carried out and plans were laid to build a much larger machine. When the Huemul results hit the news, James L. Tuck, a UK physicist working at Los Alamos, introduced the pinch concept in the US and produced a series of machines known as the Perhapsatron. In the Soviet Union, a series of similar machines were being built, unknown in the west. All of these devices quickly demonstrated a series of instabilities in the fusion when the pinch was applied, which broke up the plasma column long before it reached the densities and temperatures needed for fusion. In 1953 Tuck and others suggested a number of solutions to these problems. The largest "classic" pinch device was the ZETA, including all of these upgrades, starting operations in the UK in 1957. In early 1958 John Cockcroft announced that fusion had been achieved in the ZETA, an announcement that made headlines around the world. When physicists in the US expressed concerns about the claims they were initially dismissed. However, US experiments demonstrated the same neutrons, although me

D-³He fuel cycle

A second-generation approach to controlled fusion power involves combining helium-3 (³He) and deuterium (²H). This reaction produces a helium-4 nucleus (⁴He) and a high-energy proton. As with the p-¹¹B aneutronic fusion fuel cycle, most of the reaction energy is released as charged particles, reducing activation of the reactor housing and potentially allowing more efficient energy harvesting (via any of several speculative technologies). In practice, D-D side reactions produce a significant number of neutrons, resulting in p-¹¹B being the preferred cycle for aneutronic fusion.

[edit] p-¹¹B fuel cycle

If aneutronic fusion is the goal, then the most promising candidate may be the Hydrogen-1 (proton)/boron reaction:

¹H + ¹¹B → 3 ⁴He

Under reasonable assumptions, side reactions will result in about 0.1% of the fusion power being carried by neutrons.^[8] At 123 keV, the optimum temperature for this reaction is nearly ten times higher than that for the pure hydrogen reactions, the energy confinement must be 500 times better than that required for the D-T reaction, and the power density will be 2500 times lower than for D-T. Since the confinement properties of conventional approaches to fusion such as the tokamak and laser pellet fusion are marginal, most proposals for aneutronic fusion are based on radically different confinement concepts, such as the Polywell and the Dense plasma focus.

[edit] History of research

[edit] Brief overview

The idea of using human-initiated fusion reactions was first made practical for military purposes in nuclear weapons. In a hydrogen bomb, the energy released by a fission weapon is used to compress and heat fusion fuel, beginning a fusion reaction that releases a large amount of neutrons that increases the rate of fission. The first fission-fusion-fission-based weapons released some 500 times more energy than early fission weapons.
Attempts at controlling fusion had already started by this point. Registration of the first patent related to a fusion reactor^[9] by the United Kingdom Atomic Energy Authority, the inventors being Sir George Paget Thomson and Moses Blackman, dates back to 1946. This was the first detailed examination of the pinch concept, and small efforts to experiment with the pinch concept started at several sites in the UK.
Around the same time, an expatriate German proposed the Huemul Project in Argentina, announcing positive results in 1951. Although these results turned out to be false, it sparked off intense interest around the world. The UK pinch programs were greatly expanded, culminating in the ZETA and Sceptre devices. In the US, pinch experiments like those in the UK started at the Los Alamos National Laboratory. Similar devices were built in the USSR after data on the UK program was passed to them by Klaus Fuchs. At Princeton University a new approach developed as the stellarator, and the research establishment formed there continues to this day as the Princeton Plasma Physics Laboratory. Not to be outdone, Lawrence Livermore National Laboratory entered the field with their own variation, the magnetic mirror. These three groups have remained the primary developers of fusion research in the US to this day.
In the time since these early experiments, two new approaches developed that have since come to dominate fusion research. The first was the tokamak approach developed in the Soviet Union, which combined features of the stellarator and pinch to produce a device that dramatically outperformed either. The majority of magnetic fusion research to this day has followed the tokamak approach. In the late 1960s the concept of "mechanical" fusion through the use of lasers was developed in the US, and Lawrence Livermore switched their attention from mirrors to lasers over time.
Civilian applications are still being developed. Although it took less than ten years for fission to go from military applications to civilian fission energy production,^[10] it has been very different in the fusion energy field; more than fifty years have already passed since the first fusion reaction took place^[11] and sixty years since the first attempts to produce controlled fusion power, without any commercial fusion energy production plant coming into operation.

[edit] Magnetic containment

[edit] Pinch devices

A "wires array" used in Z-pinch confinement, during the building process

A major area of study in early fusion power research is the "pinch" concept. Pinch is based on the fact the plasmas are electrically conducting. By running a current through the plasma, a magnetic field will be generated around the plasma. This field will, according to Lenz's law, create an inward directed force that causes the plasma to collapse inward, raising its density. Denser plasmas generate denser magnetic fields, increasing the inward force, leading to a chain reaction. If the conditions are correct, this can lead to the densities and temperatures needed for fusion. The trick is getting the current into the plasma; this is solved by inducing the current from an external magnet, which also produces the external field the internal field acts against.
Pinch was first developed in the UK in the immediate post-war era. Starting in 1947 small experiments were carried out and plans were laid to build a much larger machine. When the Huemul results hit the news, James L. Tuck, a UK physicist working at Los Alamos, introduced the pinch concept in the US and produced a series of machines known as the Perhapsatron. In the Soviet Union, a series of similar machines were being built, unknown in the west. All of these devices quickly demonstrated a series of instabilities in the fusion when the pinch was applied, which broke up the plasma column long before it reached the densities and temperatures needed for fusion. In 1953 Tuck and others suggested a number of solutions to these problems.
The largest "classic" pinch device was the ZETA, including all of these upgrades, starting operations in the UK in 1957. In early 1958 John Cockcroft announced that fusion had been achieved in the ZETA, an announcement that made headlines around the world. When physicists in the US expressed concerns about the claims they were initially dismissed. However, US experiments demonstrated the same neutrons, although me