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High Beta Experiments in the GDT Axi-symmetric Magnetic Mirror

Author: Thomas C. Simonen
Requested Type: Consider for Invited
Submitted: 2010-01-27 22:10:10

Co-authors: A.V. Anikeev, P.A. Bagryansky, A.D. Beklemishev, A.A. Ivanov, A.A. Lizunov, V.V Maximov, V.V. Prikhodko, Yu.A. Tsidulko

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Abstract Text:
HIGH BETA EXPERIMENTS IN THE GDT AXI-SYMMETRIC MAGNETIC MIRROR
T.C. Simonen, Berkeley, CA., simonen42@yahoo.com
A.V. Anikeev, P.A. Bagryansky. A.D. Beklemishev, A.A. Ivanov, A.A. Lizunov, V.V. Maximov, V.V. Prikhodko, Yu.A. Tsidulko Budker Institute of Nuclear Physics, 63090, Novosibirsk, Russia
This paper describes high beta experiments carried out on GDT in Novosibirsk. It is a 7 m long mirror device with simple circular magnets with 0.3 T magnetic field with 6.5 T end mirrors. The high energy plasma (E_i = 10 keV) is produced with 2 MW of 20 keV absorbed neutral beam power injected at 45 degrees to the magnetic axis to aid micro-stability. Warm plasma is trapped between the ion turning points (at a mirror ratio of 2) and between the end magnetic mirrors (with a mirror ratio of 22) provides further micro-stability.
GDT is equipped with an array of standard diagnostics including Thomson scattering and Motional Stark Effect (MSE) to measure the magnetic field depression by the high beta plasma. Numerical simulations, including Monte Carlo packages are used to conclude that the experimental results are largely due to classical Coulomb interactions.
Sheared ExB rotation provides vortex MHD confinement. The 30% magnetic field depression indicates that the local plasma beta is ~50% (referenced to the vacuum field), or ~100% referenced to the depressed field. The plasma is near the ballooning limit and exhibits a hot-ion radial pinch as well as axial contraction.
A similar size device, but with higher magnetic field (2T) powered with higher energy beams (80 keV) would provide 2 MW/m2 neutron flux for materials and subcomponent testing neutron source). A larger size device leads to a Q ~ 1 engine for a fusion-fission hybrid. With compact axisymmetric end cells, an axi-symmetric tandem mirror power plant can be envisioned.

The first author appreciates the opportunity to have participated in these experiments in May 2009. The GDT Group is supported by the Russian Academy of Sciences.

Characterization: A2

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