U.S. Department of Energy 

Office of Science

Fusion Energy: Bringing a Star to Earth 

Summary 

Fusion energy is arguably one of the most important and rewarding research challenges of the 21st Century. 

Fusion power produces no troublesome emissions, is safe, and has few, if any, proliferation concerns. It creates 

no long-lived waste and runs on fuel readily available to all nations. The recent Presidential decision to join the 

negotiations to participate in the construction of the International Thermonuclear Experimental Reactor (ITER) is 

a critical step to a demonstration-scale fusion power plant. 

Fusion energy is already widely available. Fusion 

powers every star in the universe. The huge gravitational forces within stars allow them to confine the 

reacting fuel elements in a plasma in which the 

lighter elements fuse together to make heavier 

elements and energy. The challenge of bringing this 

power down to earth is considerable but scientists 

have already made enormous progress in this 

endeavor. 

The two principal approaches for confining the 

fusion fuel1

 on earth are magnetic and inertial. 

Magnetic fusion relies on magnetic forces to confine 

the charged particles of the hot plasma fuel while 

inertial fusion relies on intense lasers or particle 

beams to compress a pellet of fuel rapidly to the 

point where fusion occurs, yielding a burst of energy

that would be repeated to produce sustained energy. 

Determining the dynamics of confined hot plasmas, 

which contain a turbulent mix of charged particles—

subject to magnetic and electric fields, which they

must generate internally as well--has stimulated the 

rapid development of plasma physics. Understanding the behavior of these plasmas requires an understanding of fluid mechanics, magnetohydrodynamics, kinetic theory, nonlinear dynamics and the use 

of leading-edge computer simulation. Developments 

in fusion and plasma science have directly contributed to astrophysics, atomic physics, and communication sciences. There have also been many spin-offs 

in areas such as plasma processing, waste disposal, 

lighting, and space propulsion. 

 

1 Deuterium and tritium, two isotopes of hydrogen are the easiest 

elements to fuse together. The net product of this fusion is helium (an 

inert gas) and a neutron that carries most of the energy — the deuterium

in a gallon of seawater is equivalent to 300 gallons of gasoline. 

Over the last decade, there has been extraordinary

progress in the ability to model complex plasmas 

using state-of-the-art computer systems and the 

ability to measure the internal characteristics of 

plasmas at near reactor conditions (i.e., temperatures 

10 times the surface of the sun). With these advances

in simulation and instrumentation our ability to 

design and build the machines of the future has 

vastly improved 

Several inventive configurations of magnetic fields 

have been proposed to confine the plasma as it is 

heated to the conditions necessary for fusion. The 

most successful have been toroidal systems, 

especially the Russian-originated tokamak, which is 

the primary focus of world research today. The 

fusion power produced in these machines has 

improved by six orders of magnitude (from a few 

watts to megawatts) over the past two decades. 

In the past two decades, two programs have 

advanced our knowledge of magnetically confined 

plasmas. First, at the Tokamak Fusion Test Reactor 

at the Department of Energy’s (DOE’s) Princeton 

Plasma Physics Laboratory, experiments produced 

10 Megawatts of power (lasting about a second), and 

then at the larger Joint European Tokamak near 

Oxford in the U.K. they achieved longer pulses at 

higher power. In each case scientists analyzed the 

results, refining our understanding to the point 

where we can confidently proceed to the larger-scale 

ITER burning plasma experiment. 

World fusion scientists have designed several 

burning plasma experiments, in which the actual 

fusion energy process dominates the power input 

into the plasma. ITER is the result of many years of 

collaborative effort (including the U.S. through 

1998) and incorporates the world’s collective 

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understanding of how best to construct such an 

experiment. Canada, Europe, and Japan have offered 

sites for ITER and negotiations are well under way.

The cost of the ITER facility has been reduced 

almost in half (following earlier U.S. recommendations) and recent developments have also increased 

confidence that the project will meet its goals. 

The Fusion Energy Sciences Advisory Committee 

(FESAC) has concluded we are technically and 

scientifically ready to proceed with a burning plasma

experiment and has recommended joining the 

ongoing negotiations to construct ITER. The 

National Research Council of the National Academy

of Sciences has endorsed this strategy. Based on 

these recommendations and an assessment by DOE’s

Office of Science of the cost estimate for the 

construction of ITER, the President has decided that 

the U.S. should join the ITER negotiations. ITER is 

expected to be the last major step between today’s 

experiments and a demonstration plant, although 

much fusion research and development work needs 

to be done on materials and alternative fusion power 

system configurations. 

In addition to joining ITER, it will be imperative to 

continue and strengthen the basic elements that have 

provided the insights leading to the improved ITER 

design in the first place. The core U.S. strengths in 

theory and modeling, diagnostics, advanced and 

innovative concepts, and plasma and fusion technologies will be needed to ensure the success of 

ITER and the pathway to fusion energy. 

Just as the magnetic fusion energy program can gain 

leverage form international fusion research, U.S. 

fusion energy efforts may also benefit from the large 

U.S. defense program investments in inertial fusion. 

The National Ignition Facility (NIF) is many times 

larger than any previous inertial confinement device. 

It presents a unique opportunity to produce 

information on target compression that could be 

used in energy-oriented studies using ion beams or 

newer kinds of lasers to compress the targets for 

energy purposes. 

Fusion energy research offers an opportunity for this 

generation to provide for the future rather than 

borrowing from our children by depleting nonrenewable natural resources. Our scientists have 

provided the opportunity. These investments are 

needed now. 

“By the time our young children reach middle age, 

fusion may begin to deliver energy independence ... 

and energy abundance ... to all nations rich and 

poor. Fusion is a promise for the future we must not 

ignore.” (Secretary of Energy Spencer Abraham,

January 30, 2003) 

For more information, please contact:

Dr. Anne Davies, Associate Director 

Fusion Energy Sciences 

Office of Science, U.S. Department of Energy

SC-50, Germantown Building 

1000 Independence Avenue, SW 

Washington, DC 2085-1290

301-903-4941 

anne.davies@science.doe.gov 

www.ofes.fusion.doe.gov 

For more information on the Office of Science visit our website: 

www.science.doe.gov