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B
International Thermonuclear
Experimental Reactor
The Sun is currently the site of the only self-sustaining fusion reactions in our
solar system. The goal of research on magnetic confinement fusion is to build a
controlled “star on Earth”—a fusion reactor—by confining a deuterium-tritium
plasma at thermonuclear pressures with magnetic fields. Progress in this grand
quest has been steady and dramatic (Figure B.1). In the mid-1990s, two magnetic
confinement fusion devices produced multimegawatts of fusion power for a few
seconds. Thus the 11-MW Tokamak Fusion Test Reactor (TFTR) in Princeton,
New Jersey, and the 16-MW Joint European Torus (JET) in Great Britain demon-
strated it is possible to confine, heat, insulate, and control a large volume of ther-
monuclear plasma in the laboratory, at least transiently; the similar-sized JT-60U
experiment in Japan extended these results in deuterium plasmas.
The next and critically important step is to show that one can obtain more
heating from fusion reactions than is put into the reaction from external sources—a
fusion burning plasma. In both the U.S. and European landmark fusion experi-
ments, the self-heating of the plasma from fusion reactions was less than the ap-
plied external heating. The next major step in the worldwide magnetic confinement
fusion research will be to achieve a fusion burning plasma in which the plasma
is dominantly self-heated by the fusion reaction products. This step will be taken
in the International Thermonuclear Experimental Reactor, now simply known as
ITER, whose construction is slated to begin at Cadarache, in the south of France,
in 2008 (Figure B.2).
The objectives of the ITER project are as follows:
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Plasma science
222
The overall programmatic objective of ITER is to demonstrate the scientific and
technological feasibility of fusion energy for peaceful purposes.
ITER will accomplish this objective by demonstrating high power amplification and
extended burn of deuterium-tritium plasmas, with steady-state as an ultimate goal,
by demonstrating technologies essential to a reactor in an integrated system, and by
performing integrated testing of the high-heat-flux and nuclear components required
to utilize fusion energy for practical purposes.
These objectives maintain the strategy to take a single step between today’s experi-
ments and the first plant (often called DEMO) to demonstrate reliable electricity
production using fusion power.1
Specifically, ITER seeks to achieve its first plasma in 2016 and produce 500 MW
of fusion power for hundreds of seconds in about 2020. Key physical parameters
of ITER are these: the plasma cross-section will be approximately 4 meters wide by
7 meters tall; magnetic field strength, 5.3 tesla; current in the plasma, 15 MA; and
external heating power, 40-50 MW. The construction costs of ITER are estimated
at €5 billion over 10 years, and another €5 billion are foreseen for the 20-year op-
eration period. The ITER Parties will for the largest part give components for the
machine, so-called in-kind contributions.
The ITER project was launched as a Reagan-Gorbachev Presidential Initiative
in 1985, with equal participation by the United States, Europe, Japan, and the Soviet
Union through the 1988-1998 initial design phases of the original ITER project.
After the fusion program budget was cut by 33 percent and the fusion program was
restructured from an energy technology development program to a science-focused
program in the late 1990s, the United States withdrew from the ITER project. From
1998 through 2002 the ITER project was continued by Europe, Japan, and Russia
and evolved into the current smaller ITER project with reduced objectives. It ad-
opted much of the science-driven reduced scope and advanced concepts the United
States had pushed for when it participated in the earlier ITER phases.
The NRC Burning Plasma Assessment Committee (BPAC) recommended (in
December 2002) that the United States should again participate in the ITER proj-
ect. The United States then rejoined the ITER negotiations in January 2003 as a
Presidential Initiative. Participation in ITER is now identified as the number one
priority future project over the next 20 years by the DOE Office of Science. In the
Energy Policy Act of 2005 (Public Law 109-58, August 8), Congress authorized the
negotiation of “an agreement for United States participation in the ITER.” Achieve-
ment of the U.S. scientific community and government consensus on rejoining
ITER was a major accomplishment over the past decade.
The partners in the ITER project (host Europe, 45 percent; nonhosts—China,
1As defined on the ITER Web site at http://www.iter.org/a/index_nav_1.htm. Last viewed May 15,
2007.
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FIGURE B.1 The fusion power produced in magnetically confined plasmas has been increasing continuously and dramatically for decades. On aver-
age it doubled every year until the mid-1990s, twice as fast as Moore’s law for the increase in computing power of semiconductor chips. ITER is
projected to extend fusion power and duration to the crucial burning plasma regime.
22
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Plasma science
224
FIGURE B.2 Cutaway drawing of the International Thermonuclear Experimental Reactor (ITER) to be
built over the next decade in Cadarache, France. A man shown in the lower left corner indicates the
scale of the device. Detailed characteristics of the ITER device and of the overall ITER project can be
obtained from http://www.iter.org. Published with permission of ITER.
India, Japan, Russia, South Korea, and the United States—9.1 percent each), de-
cided on the Cadarache site on June 28, 2005, and initialed an agreement on May
24, 2006. Final governmental signatures on the ITER Agreement were obtained on
November 21, 2006. Because the ITER project has been truly international from
its inception in 1985 as an initiative of Presidents Reagan and Gorbachev and is
the largest joint international scientific endeavor ever undertaken, it will probably
become the model for large international science experiments.
Magnetic fusion research has a long history of strong international collabora-
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aPPendix B 22
tion ever since it was declassified at the United Nations Atoms for Peace conference
in 1958. During the 1960s, the major players were the United States, Great Britain
and the Soviet Union; scientific exchanges began then, but there were few close
collaborations. A notable turning point in fusion research was the achievement
in 1968 of excellent plasma confinement in the Soviet T-3 tokamak experiment
and subsequent confirming measurements by a collaborating team of British
scientists. This achievement launched a worldwide quest for fusion energy based
primarily on the tokamak concept. The major players became the United States,
Europe (Great Britain, France, and Germany), the Soviet Union, and Japan. The
United States had about a third of the world fusion budget in 1980 and became the
dominating leader in fusion science and technology in the late 1970s; its leadership
continued into the early 1990s. Close collaborations between experimental teams
on different fusion devices around the world are now quite common, most often
to check scaling of the behavior of plasma phenomena across different sizes and
types of experiments. While the primary U.S. objective in ITER is burning plasma
science (understanding and control of burning plasmas), the primary objective of
the European and Japanese programs remains development of fusion energy for
commercial electricity production.
