TANDEM MIRROR PHYSICS AND TMX

Abstract

The Tandem Mirror Experiment (TMX) is being built at Livermore to test the principles of the new tandem mirror reactor concept. In this concept the fusion plasma is confined in a long solenoid terminated at each end by mirror machines of the magnetic-well type. High density plasmas are maintained in each of the mirror end cells by neutral injection at high energies (up to 1 Mev in a high Q reactor). The usual positive ambipolar potential that automatically develops in each mirror cell serves as an electrostatic barrier that confines ions in the solenoid for many collision times, and the very stable plasmas in these end cells “anchor” each flux tube, thereby assuring MHD stability of the system up to betas of order unity in the solenoid. The TMX will test these main features of the tandem mirror idea and will also investigate optimum means of suppressing loss cone instabilities in the end cells based on methods demonstrated in the 2XIIB experiment. The end cells will be similar in size and injected power to 2XIIB, but some injectors will operate at 40 kV. Expected parameters are nτ ~ 1011 cm–3 sec at ion energies of 20 keV in the end plugs and nτ ~ 1–3 × 1011 cm-3 sec in the solenoid at ion temperatures up to 2 keV if auxiliary beam heating is applied to the solenoid. The solenoid field will be variable up to about 4 kG and the length is 5 meters. The facility is nearing completion (18 months construction time) and experiments are expected to begin early in 1979.