Ion temperature measurements on the ZT-40M reversed field pinch

A VUV seven-channel polychrometer was constructed for measuring line broadening at wavelengths from 1500 to 3000 A. This instrument uses a cylindrical sapphire lens to expand the line image at the exit slit. The average width between channels is 0.3 A at 1623 A with an average channel width of ∼ 0.24 A. Measurement made on the Los Alamos ZT-40 M reversed field pinch yield ion temperatures up to approximately 500 eV. Measurements have been made for 0+6 1623 A, N+5 1897 A, and C+4 2271 A. The O+6 provides temperature measurements primarily from the center of the plasma. The measured ion temperatures are comparable to the electron temperatures measured at the center of the discharge. The discharges used in these studies were short, the total length being ∼ 1.51 ms. The ions appear to be heated quickly to several hundred electron volts. For a given peak plasma current the ion temperature increases with increasing drift velocity. Some discussions of these results will be presented