JT-60
Encyclopedia
JT-60 is the flagship of Japan
's magnetic fusion
program, previously run by the Japan Atomic Energy Research Institute
(JAERI) and currently run by the Japan Atomic Energy Agency
's (JAEA) Naka Fusion Institute http://www.naka.jaea.go.jp/english/NAKA-HPe.html in Ibaraki Prefecture
, Japan
. In operation since 1985, it currently holds the record for the highest value of the fusion triple product achieved: = .
JT-60 is a typical Tokamak
with a D-shaped poloidal cross-section, similar to JET
. Experimental results obtained by the reactor will no doubt be of great importance to the ITER
experiment.
During deuterium
(D–D fuel) plasma experiments in 1998 plasma conditions were achieved which would, if the D–D fuel were replaced with a 1:1 mix of deuterium
and tritium
(D–T fuel), have exceeded break-even—the point where the power produced by the fusion reactions equals the power supplied to operate the machine. JT-60 does not have the facilities to handle tritium; currently only the JET
tokamak in the United Kingdom
has such facilities. In fusion terminology JT-60 achieved conditions which in D–T would have provided Q
= 1.25, where Q is the ratio of fusion power to input power. A self-sustaining nuclear fusion reaction would need a value of Q that is greater than 5.
On May 9, 2006, the JAEA announced that the JT-60 had achieved a 28.6 second plasma duration time. The JAEA used new parts in the JT-60, having improved its capability to hold the plasma in its powerful toroidal magnetic field. The main future objective of JT-60 is to realize high-beta steady-state operation in the use of reduced radio-activation ferritic
steel in a collision-less regime.
In 2010 JT-60 is being disassembled to be upgraded to JT-60SA by using niobium-titanium
superconducting coils. Construction of JT-60SA was underway in 2010 and will continue until at least 2016.
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
's magnetic fusion
Fusion power
Fusion power is the power generated by nuclear fusion processes. In fusion reactions two light atomic nuclei fuse together to form a heavier nucleus . In doing so they release a comparatively large amount of energy arising from the binding energy due to the strong nuclear force which is manifested...
program, previously run by the Japan Atomic Energy Research Institute
Japan Atomic Energy Research Institute
The Japan Atomic Energy Research Institute is a former semi-governmental organization that existed for the purpose of further nuclear power in Japan. It was created June 1956 by the Atomic Energy Basic Law...
(JAERI) and currently run by the Japan Atomic Energy Agency
Japan Atomic Energy Agency
The was formed October 1, 2005 by a merger of two previous semi-governmental organizations. While it inherited the activities of both PNC and JAERI, it also inherited the nickname of JAERI, "Genken" 原研, an abbreviated word for "nuclear research"....
's (JAEA) Naka Fusion Institute http://www.naka.jaea.go.jp/english/NAKA-HPe.html in Ibaraki Prefecture
Ibaraki Prefecture
is a prefecture of Japan, located in the Kantō region on the main island of Honshu. The capital is Mito.-History:Ibaraki Prefecture was previously known as Hitachi Province...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. In operation since 1985, it currently holds the record for the highest value of the fusion triple product achieved: = .
JT-60 is a typical Tokamak
Tokamak
A tokamak is a device using a magnetic field to confine a plasma in the shape of a torus . Achieving a stable plasma equilibrium requires magnetic field lines that move around the torus in a helical shape...
with a D-shaped poloidal cross-section, similar to JET
Joint European Torus
JET, the Joint European Torus, is the largest magnetic confinement plasma physics experiment worldwide currently in operation. Its main purpose is to open the way to future nuclear fusion experimental tokamak reactors such as ITER and :DEMO....
. Experimental results obtained by the reactor will no doubt be of great importance to the ITER
ITER
ITER is an international nuclear fusion research and engineering project, which is currently building the world's largest and most advanced experimental tokamak nuclear fusion reactor at Cadarache in the south of France...
experiment.
During deuterium
Deuterium
Deuterium, also called heavy hydrogen, is one of two stable isotopes of hydrogen. It has a natural abundance in Earth's oceans of about one atom in of hydrogen . Deuterium accounts for approximately 0.0156% of all naturally occurring hydrogen in Earth's oceans, while the most common isotope ...
(D–D fuel) plasma experiments in 1998 plasma conditions were achieved which would, if the D–D fuel were replaced with a 1:1 mix of deuterium
Deuterium
Deuterium, also called heavy hydrogen, is one of two stable isotopes of hydrogen. It has a natural abundance in Earth's oceans of about one atom in of hydrogen . Deuterium accounts for approximately 0.0156% of all naturally occurring hydrogen in Earth's oceans, while the most common isotope ...
and tritium
Tritium
Tritium is a radioactive isotope of hydrogen. The nucleus of tritium contains one proton and two neutrons, whereas the nucleus of protium contains one proton and no neutrons...
(D–T fuel), have exceeded break-even—the point where the power produced by the fusion reactions equals the power supplied to operate the machine. JT-60 does not have the facilities to handle tritium; currently only the JET
Joint European Torus
JET, the Joint European Torus, is the largest magnetic confinement plasma physics experiment worldwide currently in operation. Its main purpose is to open the way to future nuclear fusion experimental tokamak reactors such as ITER and :DEMO....
tokamak in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
has such facilities. In fusion terminology JT-60 achieved conditions which in D–T would have provided Q
Fusion energy gain factor
The fusion energy gain factor, usually expressed with the symbol Q, is the ratio of fusion power produced in a nuclear fusion reactor to the power required to maintain the plasma in steady state. The condition of Q = 1 is referred to as breakeven.In a fusion power reactor a plasma must be...
= 1.25, where Q is the ratio of fusion power to input power. A self-sustaining nuclear fusion reaction would need a value of Q that is greater than 5.
On May 9, 2006, the JAEA announced that the JT-60 had achieved a 28.6 second plasma duration time. The JAEA used new parts in the JT-60, having improved its capability to hold the plasma in its powerful toroidal magnetic field. The main future objective of JT-60 is to realize high-beta steady-state operation in the use of reduced radio-activation ferritic
Ferrite (iron)
Ferrite or alpha iron is a materials science term for iron, or a solid solution with iron as the main constituent, with a body centred cubic crystal structure. It is the component which gives steel and cast iron their magnetic properties, and is the classic example of a ferromagnetic material...
steel in a collision-less regime.
In 2010 JT-60 is being disassembled to be upgraded to JT-60SA by using niobium-titanium
Niobium-titanium
Niobium-titanium is an alloy of niobium and titanium, used industrially as a type II superconductor wire for superconducting magnets...
superconducting coils. Construction of JT-60SA was underway in 2010 and will continue until at least 2016.