Suppression of ion emission and pinching using heated tantalum anodes in high-power electron-beam diodes

Pulse-heating tantalum anodes to > 2200 K results in drastic changes to ion emission and beam dynamics. The ion current starts later, the peak ion current is reduced, and beam pinching is suppressed or eliminated. The diode current follows a single-species Child-Langmuir formula until the voltage exceeds 1 MV, then follows a critical current formula, indicating that ions have little effect on the diode impedance. The experiments indicate a definite dependence on different heating procedures. This technique can be used to improved x-ray production on high-power generators such as Decade.