Research Needs for Magnetic Fusion Energy Sciences - US Burning ...

thE coMpact toRuS: FRc aNd SphERoMak
introduction
The mission of compact torus (ct) research is to:
Develop a compact magnetic fusion reactor without toroidal field coils or a central solenoid.
Progress in this mission is supported by the iteR-era goal established by taP:
To demonstrate that a CT with a simply connected vessel can achieve stable, sustained or long pulsed plasmas
at kilovolt temperatures, with favorable confinement scaling to proceed to a pre-burning CT plasma
experiment.
a ct has a toroidal magnetic and plasma geometry, but is contained within a simply connected
vacuum vessel such as a cylinder or sphere. spheromaks and field-reversed configurations fall into
this category. compact tori have high plasma and engineering betas, potentially obtaining highpower
density at relatively low magnetic fields. The primary benefit of cts for fusion is the absence
of toroidal field coils, simplifying solutions to many engineering problems. studying highbeta,
fusion-relevant plasma in simply connected geometries affords both physics and technology
opportunities not found in other configurations, in a program in which the Us is the world leader.
The ct program currently consists of experiments at the concept exploration level, involving both
the spheromak and the FRc, and other hybrid configurations may be possible. ct funding has traditionally
been a small part of the alternate concepts program, but both the spheromak and FRc
configurations have made substantial plasma physics progress in recent years, pointing the way
to future research on ct science and technology opportunities.
Axial-eld
bias coils
Figure 6. On the left is the field-reversed configuration and on the right is the spheromak configuration. No
physical structure links the plasma torus in these configurations.
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Spheromak plasma with
magnetic eld lines
Flux
Conserver