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A method to exhaust energy and ash from small, aneutronic FRC reactors

Author: Samuel A Cohen
Requested Type: Consider for Invited
Submitted: 2012-12-07 12:14:51

Co-authors: M. Chu-Cheong, A. Creely, A. Glasser, M. Khodak, E. Meier, C. Myers, T. Rognlien, A. Sefkow and D. Welch

Contact Info:
PPPL
Forrestal Campus
Princeton, NJ   08543
USA

Abstract Text:
Power and ash exhaust from magnetic fusion reactors that burn advanced (low-neutron) fuels will be more demanding than for D-T-fueled reactors because a much greater fraction of the fusion products and power are contained within the advanced-fuel-burning plasma. We describe how both fusion power and ash can be effectively removed from the core plasma of an advanced-fuel-burning reactor to its scrape-off layer (SOL) if the reactor is a small field-reversed-configuration (FRC) device. Once the fusion power is in the FRC’s SOL, its linear geometry allows large plasma expansion in remote divertors, thus reducing the peak heat load to acceptable values.
The process relies on fusion-product slowing down in the FRC’s SOL, a rapid process in the FRC’s relatively cool SOL. In a small D-3He-burning FRC reactor, the problematic fusion products are 4He, p, and T. At birth, these ions will have gyroradii about 1/3 as large as the O-point-to-separatrix distance, hence many will pass through the SOL even on their first orbits. We show that once even a small portion of the fast ion trajectory passes through the SOL the ions rapidly lose energy there, in less than 0.1 s, and guiding centers migrate to the SOL.
We use the FieldCoils code to calculate the magnetic field, a modified version of the RMF code to illustrate the transition of ion trajectories from betatron to figure-8 to cyclotron orbits and to calculate the fraction of fusion products that pass through the SOL, the UEDGE code to calculate the SOL and divertor parameters for a variety of fueling and heating scenarios, and the LSP code to calculate the fast-ion slowing down in the SOL, a novel situation because the Debye length is less than the electron gyroradius and the fast-ion velocity is larger than the electron thermal velocity.

Characterization: 1.0

Comments:
The talk could fit into several categories 1, 1.1, 1.2, 3.0 and 4.0