Longitudinal Confinement of Particles and Energy in a Gas-Dynamic Trap

The influence of the expanding magnetic field beyond the mirror region of an open magnetic con- finement system on the electron heat flux is studied experimentally in a gas-dynamic trap with a plasma absorber whose emissivity can be considered infinitely large. With an expansion ratio higher than 40-50, the ambipolar potential in the device and the electron heat flux are shown to be independent of the emission prop- erties of the plasma absorber. The plasma parameters in the expander (the mean electron energy, the plasma potential, the fluxes of particles and energy through the magnetic mirror, and the energy spectrum of the ions leaving the device) are studied in detail. The experimental dependences relating the plasma parameters in the expander to those in the device are found. The results obtained are compared with theoretical predictions.