f FERMI NATIONAL ACCELERATOR LABORATORY US DEPARTMENT OF
f FERMI NATIONAL ACCELERATOR LABORATORY US DEPARTMENT OF ENERGY Possible Accelerator Applications for Nuclear Fusion Y. Alexahin Future Directions for Accelerator R&D at Fermilab, Lake Geneva, WI May 11 -13 2009
2 Outline Intense Particle Beams for Plasma Magnetic Confinement Astron “Colliding Beam Fusion Reactor” Inertial Confinement with Heavy Ion Beams Induction linac-based HIF HIDIF with ion storage rings D+T collider ideas Summary Disclaimer: I am not a fusion specialist or enthusiast, just got to know some of them by chance Accelerators for Fusion - Y. Alexahin May 13,
3 Magnetic Field Reversal with Particle Beams 1958: Nicholas Christifilos published the idea of the Astron fusion reactor For the Astron injector Christifilos (re)invented and constructed the first ever electron induction linac (1968 upgrade parameters U=6 Me. V, I=600 A). 1974: R. N. Sudan, E. Ott (Cornell University Laboratory of Plasma Studies) proposed to use intense ion rings for creating field reversal. 1978: field reversal achieved by H. Fleischmann et al. with the Cornell University RECE Christa device (using multi-k. A electron rings). 2000: H. Monkhorst (UF? ) & N. Rostoker (UC Irvine) founded Tri Alfa Energy to develop “Colliding Beam Fusion Reactor (CBFR)” = Astron with p and 11 B layers instead of e-layer. Besides self-confinement, these layers produce energy via p + 11 B 3 Allegedly Tri Alfa raised 40 M$ for the project, mostly from private investors. Accelerators for Fusion - Y. Alexahin May 13,
4 Magnetic Field Reversal with SC Coil A surprise offspring of the “Astron” idea: The LDX team - a collaboration between Columbia University and MIT - has since successfully conducted its first levitation tests, including a 40 minute suspension of the Nb 3 Sn superconducting coil on February 9, 2007. It is not clear how they hope to protect the SC floating coil from heat (HTS? ). Will benefit from aneutronic reaction (e. g. D + 3 He + p) and electrostatic insulation. - a good candidate for participation Alvin’s HTS collaboration. Accelerators for Fusion - Y. Alexahin May 13,
5 Heavy Ion Inertial Fusion (HIF, USA) 1968: F. Winterberg proposed Inertial Confinement Fusion with e- or ion beams HIF with induction linac is pursued by “the Heavy Ion Fusion Science Virtual National Laboratory” (LBNL, LLNL and PPPL), funded by Do. E Accelerators for Fusion - Y. Alexahin May 13,
6 Heavy Ion Driver for Inertial Fusion (HIDIF, Europe) 1995: GSI (Ingo Hofmann more precisely) initiated a Study Group to investigate, on an advanced level, the feasibility for a Heavy Ion Driver for Inertial Fusion (HIDIF). Energy / Bi ion Total energy 10 Ge. V 3 MJ (1015 Bi ions) A total number of 6 to 12 storage rings arranged in two stacks delivering 144 beamlets, which are compressed in induction bunchers. Preliminary report published in 1998. ITEP (Moscow) participates in HIDIF studies, plans to build ITEP-TWN: a storage ring for TW ion beams (besides that, they are working on “ELIANG” = Electro-nuclear neutron generator). This direction in fusion research seems quite appropriate for Fermilab, BNL and ORNL, the scheme (high-current RF linac + storage/compressor rings) is similar to that of Project-X. However, it may be difficult to gain the Do. E support since it has already made its choice in favor of the induction linac-based HIF. Accelerators for Fusion - Y. Alexahin May 13,
7 “Accelerator-Based Fusion” (M. Albrow, 2008) Motivation: in thermal equilibrium at 108 K only Maxwellian tails have energy corresponding to maximum crosssection Original Mike’s idea: form T-beam collide with D 2 gas target, recirculate until most T’s are fused every turn replenish energy lost in the target Problem: ionization losses exceed the yield Possible solution: pre-ionize D target or, better, make a D+T collider: cooler, energy replenisher D T (courtesy of S. Striganov) Questions: Coulomb scattering charge neutralization cooling and reacceleration of neutralized beams 50 T solenoid Accelerators for Fusion - Y. Alexahin May 13,
8 Coulomb Scattering cross-section (courtesy of S. Striganov) Probablity of scattering to angle > For =0. 1 rad and n 2=3· 1017 P=0. 045 /m To reduce Pscatter / Pfusion we should increase CMS momentum p. p + 11 B 3 cross-section peaks at CMS energy of 550 ke. V, as compared to 64 ke. V for D+T - some glimmer of hope. Probablity of fusion Pf= f n 2 L=1. 5· 10 -4 /m, or 300 times smaller! Accelerators for Fusion - Y. Alexahin May 13,
9 ECOfusion D. J. Larson, Larson Technical Solutions, Inc. 8800 Melissa Court, Waxahachie, TX 751 Idea: collide D+T at low-beta IPs e-cool both beams replenish D & T energy with the same e-beams! Problem: For D & T currents of interest (up to 1 MA) the electrostatic potential (in absence of neutralization) would exceed 1 MV, whereas electron energy should be 10 e. V - small fluctuations in D & T densities will disrupt e-beam. Still, the idea deserves a closer look, especially for p + 11 B 3 case Accelerators for Fusion - Y. Alexahin May 13,
10 Summary The Astron idea in the Tri Alfa Energy rendition looks attractive, but we can offer too little for it. Collaboration with the Levitating Dipole team may be interesting form the point of view of the HTS technology development. Heavy Ion Driver for Inertial Fusion (HIDIF) based on RF linac and ion storage rings is within the area of FNAL expertise. Collaboration can be formed with BNL, ORNL and other Do. E labs as well as with GSI, ITEP and other labs worldwide. p + 11 B collider with electron cooling / reacceleration deserves a closer look. Accelerators for Fusion - Y. Alexahin May 13,
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