Field-Reversed Configuration
Fusion Power Plants
John F. Santarius
University of Wisconsin
Workshop on Status and Promising
Directions for FRC Research
PPPL
June 8-9, 1999
Collaborators
 University of Wisconsin
 Canh Nguyen
Laila El-Guebaly
 Gil Emmert
Doug Henderson
 Hesham Khater
Jerry Kulcinski
 Elsayed Mogahed
Sergei Ryzhkov
 Mohamed Sawan
 University of Washington
 Loren Steinhauer
 University of Illinois
 George Miley
JFS 1999
University of Wisconsin
FRC Power Plant Applications
D-T
D-3He
Commercial
electricity
production
Solid walls
Hydrogen
production?
JFS 1999
Proliferation
-resistant
electricity
Space
propulsion
Liquid walls
Destruction
of waste?
University of Wisconsin
Other
applications?
Field-Reversed Mirror (D-T, Condit, et al., LLNL, 1976)
JFS 1999
University of Wisconsin
SAFFIRE Field-Reversed Mirror
(D-3He, Miley, et al., Univ. of Illinois, 1978)
JFS 1999
University of Wisconsin
ARTEMIS Field-Reversed Configuration
(D-3He, Momota, et al., NIFS, 1992)
JFS 1999
University of Wisconsin
A D-T FRC Engineering Scoping Study
Is In Progress
 Collaboration of Universities of Wisconsin, Washington,

and Illinois.
Objective: To investigate critical engineering issues for
D-T FRC Power Plants.
 Systems analysis
 Tritium-breeding blanket design
 Radiation shielding and damage
 Activation, safety, and environment
 Plasma modeling
 Current drive
 Plasma-surface interactions
JFS 1999
University of Wisconsin
FRC Plasma Power Flows Differ
Significantly from Tokamak Power Flows
 Power density can be very high due to its b2B4 scaling, but this does not



necessarily imply an unmanageable first-wall heat flux.
Charged-particle power transports from internal plasmoid to edge region
and then out ends of fusion core.
Expanded flux tube in end chamber reduces heat and particle fluxes, so
charged-particle transport power only slightly impacts the first wall.
Mainly bremsstrahlung power contributes to first-wall surface heat.
 Relatively small peaking factor along axis for bremsstrahlung and
neutrons.
Not to scale
Neutrons
FRC core region
Expanded
flux tube to
reduce
heat flux
Bremsstrahlung
Charged particles
JFS 1999
University of Wisconsin
Linear Geometry Greatly Facilitates Engineering



Flow of charged particles to end plate reduces first-wall
surface heat flux.
Modules containing blanket, shield, and magnet can be
replaced as single units due to their moderate mass.
Maintenance should be easier and improve reliability and
availability.
 Considerable flexibility exists for placement of pipes,
manifolds, etc.

Direct conversion of transport power to electricity could
increase net efficiency.
JFS 1999
University of Wisconsin
FRC Geometry Greatly Reduces the
‘Divertor’ Problem


MHD tilt instability, probably the closest FRC analogue
to a tokamak disruption, will send the plasma along the
axis and into the end chamber, where measures can be
more easily taken to mitigate and localize the effects.
Steady-state heat flux is broadly spread and due almost
exclusively to bremsstrahlung radiation power.
 Edge region vacuum pumps well and should shield the
core plasma from most impurities..
JFS 1999
University of Wisconsin
Compact Toroids Might Provide both
Fueling and Current Drive for FRC’s



Compact toroids carry particles and current at 100’s of
km/s.
Small spheromaks merging with a large FRC will relax
to an FRC with a slightly larger current.
Added helicity must balance resistive decay of the
plasma current.
 Added particles should balance particle transport losses.
 Spheromaks would be injected at ~1 Hz.
 Either vertical or horizontal geometry should work.
 Key question is power required for self-consistent
fueling and current drive.
JFS 1999
University of Wisconsin
D-T FRC Engineering Scoping Study
Key Assumptions
 Rotating magnetic field (RMF) current drive.
 Steady-state operation.
 He/Li20/SiC for coolant/breeder/structure of first
wall and blanket.
 Superconducting magnets, possibly high-Tc.
 Thermal energy conversion only.
 Horizontal (radial) maintenance of
blanket/shield/magnet modules (~5 m length).
 ARIES economic model assumptions.
JFS 1999
University of Wisconsin
Liquid-Walled FRC Power Plants Might
Achieve Extremely High Power Densities
 The APEX study uses the FRC as a key alternate to the

tokamak.
Thick liquid walls (Li, Flibe, LiPb, LiSn) would
attenuate neutrons and serve as
 Tritium breeder
 Radiation shield
 Heat transfer medium
magnet
spheromak for
fueling and
current drive
solid shield
liquid wall
edge plasma
core plasma
Not to scale
JFS 1999
University of Wisconsin
FRC Magnets Fit Well within
Superconducting State-of-the-Art


Magnetic fields for both D-T and D-3He FRC power-plant
coils are usually projected to be <6 T.
Externally generated field within fusion core nearly equals
the field on the coils  increased power density (B4).
 MHD pressure drop for liquid-metal coolants will require
less pumping power than in tokamaks.


High-temperature superconductors presently operate at
relevant current densities at 5 T in short lengths.
High-temperature superconductors should be more resistant
to quenching and may, therefore, reduce the required
radiation shield.
JFS 1999
University of Wisconsin
Pulsed FRC Power Plants
 High FRC power density gives flexibility that would help



accommodate changes necessitated by pulsing.
High-temperature superconductors would facilitate a
pulsed design.
 Neutron-fluence limited, therefore unaffected by
pulsing, rather than heat-flux limited.
 More robust against quenching due to pulsed fields.
Might be fueled by periodic CT injection for fueling and
current drive.
 Also potentially for inducing instability for ash
removal and plasma MHD conversion?
Transport implications?
JFS 1999
University of Wisconsin
D-3He Fuel Could Make Good Use of the
High Power Density Capability of FRC’s


D-T fueled innovative concepts become limited by firstwall neutron or surface heat loads well before they reach
b or B-field limits.
D-T fueled FRC’s optimize at B  3 T.
 D-3He needs a factor of ~80 above D-T fusion power
densities.
 Fusion power density scales as b2B4.
 Superconducting magnets can reach at least 20 T.
 Potential power-density improvement by increasing
B-field to limits is (20/3)^4 ~ 2000 !
JFS 1999
University of Wisconsin
Proliferation-Resistant FRC Power Plant
May Be Possible (Probably Requires D-3He)
High-b for high fusion
power density
Minimal radiation
shield to reduce
space for D-T
shielding
Direct converter
for increased
electric power
per unit fusion
power
Organic coolant to
make high-flux D-T
operation difficult.
JFS 1999
Small plasma
to reduce
space for D-T
shielding
University of Wisconsin
Superconducting,
high-field magnet
for high fusion
power density
Conclusions
 From a fusion energy development perspective,
FRC’s occupy the important position of leading the
b-driven, engineering-attractiveness route.
 The cylindrical geometry and disruption-free
operation of D-T FRC’s should allow them to
overcome the major engineering obstacles facing
D-T tokamaks.
 FRC’s match D-3He fuel well, and the combination
potentially could outperform D-T.
JFS 1999
University of Wisconsin