Doppler broadening measurements in FRX-C/LSM

Measurements obtained in situ during field reversed configuration (FRC) formation show that the Doppler broadening ion temperature TCV is larger by a factor of two or more than the ion temperature Ti derived from pressure balance and Thomson scattering. After a time comparable to an ion-ion equilibrium time, TCV and Ti come into agreement with each other. An exception to this picture occurs in the lowest fill pressure condition (2 mtorr), for which TCV > Ti is maintained throughout the FRC lifetime. Earlier Doppler broadening measurements in FRX-B and FRX-C also showed persistent, anomalously high TCV at low fill pressure. The initially high values of TCV are probably caused by convective motion generated by the radial implosion. The low fill pressure results suggest an enhanced ohmic power input to the carbon ions. 7 refs., 3 figs