Flux, energy, and particle lifetime measurements for well formed field reversed configurations

Abstract

Experimental flux, energy and particle lifetimes are reported for a wide range of plasma conditions (Ti = 100–800 eV, rs = 3.5–7 cm) in the slow risetime TRX-2 field reversed theta pinch. The lifetimes exhibit a scaling with the parameter rs/ρi01/2 to an exponent of between 2.7 and 3.6. This favourable scaling, especially for the flux lifetime, implies an average plasma resistivity which scales as the drift parameter vE/vi to some power greater than unity. For present small devices, typical flux diffusion coefficients are about 4 m2·s−1 and, based on the above scaling, would decrease rapidly in larger devices with smaller pressure gradient scalelengths. The above scaling is obtained only for well formed FRCs with low levels of formation turbulence, and it remains to be seen if this low turbulence level can be maintained in larger, less kinetic, FRCs.