1. 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

2. University of WisconsinJFS 1999Collaborators  University of Wisconsin  Canh NguyenLaila El-Guebaly  Gil EmmertDoug Henderson  Hesham KhaterJerry Kulcinski  Elsayed MogahedSergei Ryzhkov  Mohamed Sawan  University of Washington  Loren Steinhauer  University of Illinois  George Miley

3. University of WisconsinJFS 1999 FRC Power Plant Applications

4. Field-Reversed Mirror (D-T, Condit, et al., LLNL, 1976) University of Wisconsin JFS 1999

5. University of WisconsinJFS 1999 SAFFIRE Field-Reversed Mirror (D- 3 He, Miley, et al., Univ. of Illinois, 1978)

6. University of WisconsinJFS 1999 ARTEMIS Field-Reversed Configuration (D- 3 He, Momota, et al., NIFS, 1992)

7. University of WisconsinJFS 1999 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

8. University of WisconsinJFS 1999 FRC Plasma Power Flows Differ Significantly from Tokamak Power Flows  Power density can be very high due to its  2 B 4 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.

9. 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. University of Wisconsin JFS 1999

10. University of WisconsinJFS 1999 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..

11. University of WisconsinJFS 1999 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.

12. University of WisconsinJFS 1999 D-T FRC Engineering Scoping Study Key Assumptions  Rotating magnetic field (RMF) current drive.  Steady-state operation.  He/Li 2 0/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.

13. University of WisconsinJFS 1999 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

14. University of WisconsinJFS 1999 FRC Magnets Fit Well within Superconducting State-of-the-Art  Magnetic fields for both D-T and D- 3 He 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 (B 4 ).  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.

15. University of WisconsinJFS 1999 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?

16. University of WisconsinJFS 1999 D-3He Fuel Could Make Good Use of the High Power Density Capability of FRC’s  D-T fueled innovative concepts become limited by first- wall neutron or surface heat loads well before they reach  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  2 B 4.  Superconducting magnets can reach at least 20 T.  Potential power-density improvement by increasing B-field to limits is (20/3)^4 ~ 2000 !

17. University of WisconsinJFS 1999 Proliferation-Resistant FRC Power Plant May Be Possible (Probably Requires D- 3 He)

18. University of WisconsinJFS 1999Conclusions  From a fusion energy development perspective, FRC’s occupy the important position of leading the  -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- 3 He fuel well, and the combination potentially could outperform D-T.