Techniques and results are given for various measurements made on a highly ionized helium plasma in a steady‐state plasma system (which employs a longitudinal magnetic field of approximately 1 kilogauss). Neutral‐particle pressures ranged from about 3 × 10−4mm Hg near the source to about 10−5mm Hg in the downstream region. Spectroscopic measurements showed principal impurities were C, N, and O ions (up to C3+, N4+, and O4+states). Doppler broadening measurements of He+&lgr;4686 revealed ion temperatures up to 10 eV. Probe measurements indicated electron temperatures up to 20 eV and maximum ion densities of a little over 1013cm−3. Microwave transmission measurements (at &lgr; = 4 mm and 8 mm) gave supporting evidence that the electron density exceeds 1013cm.