Spectroscopic measurements on a titanium plasma gun with hydrogenated electrodes

The plasma produced by a plasma gun which consists of concentric titanium and tantalum washers has been observed in the plasma gun as well as in a drift tube in which the plasma particles have been injected. Axial drift velocities of hydrogen and impurities have been determined in the drift tube by optical time-of-flight measurements. Maximum hydrogen velocities between 9·10⁶ to 1·10⁸ cm/sec could be determined, in agreement with magnetic probe-, Faraday cup-, microwave-, and electrostatic energy analyser measurements. The plasma which is produced within the plasma gun by a powerful discharge (vacuum arc) has been observed with a framing camera, spectrographs and photomultipliers. From end-on observed time resolved spectrograms the temperatures and electron densities have been determined as a function of time. The measurements indicate that thermal equilibrium is reached about 2·5 μsec after the firing of the main discharge. 4 μsec after the beginning of the main discharge a maximum temperature of about 72000° K is reached. The measurements further indicate that the high-energy part of the ejected particles is produced before an equilibrium state in the plasma gun has been established.