Abstract
Coaxial plasma guns operating with about 20 kV applied at a peak current of approximately 80 kA are shown to produce a fast burst of clean plasma containing no other ions than H+. Densities of about 1011 cm-3 are measured at distances of 100 cm from the gun for ions of energy between 5 keV and 20 keV: peak ion energies of about 70 keV are observed. In the slow plasma following the fast burst the impurity ions are mainly copper.
The ion density depends on the amount of gas admitted before firing the gun, but does not vary much with gun voltage.
The measured ion velocity perpendicular to the guide field is within a factor two of the predictions of a simple theory. Discrepancies are expected because the ions do not appear in a field-free region, as the theory assumes.