Millisecond Pulsed Arc Discharge in a Forevacuum-Pressure Plasma-Cathode Electron Source

摘要

We have explored the parametric behavior of a quasi-continuous (1.8 ms) vacuum arc discharge operating as plasma source of a forevacuum-pressure plasma-cathode electron beam source. The current-voltage characteristic of the arc is presented and we show that the discharge becomes unstable at a current below 5–6 A (for our copper cathode). The operating discharge voltage increases weakly with increasing arc current over the pressure range 3–15 Pa. At a pressure greater than 15 Pa the arc shows two possible modes, differing in discharge voltage, as observed earlier for submillisecond arcs. The ratio between the currents to the hollow and plane anode sections are measured to study the arc modes. It is shown that discharge current and pressure affect that ratio. The influence of the arc modes on the electron emission in the forevacuum pressure range is discussed.