Electron Beam Switching Experiments in the High Current Gain Regime
Abstract
High energy switch technology for fast switching times has been dominated by spark gap type switches. There is however a need for switches which can handle high energies on a repetitive, long term basis and, even more important, can also switch off large energies. One of the more promising candidates for such applications is a gas discharge ionized by an external electron beam which can rapidly and repetitively be switched on and off. Selecting the proper operating conditions, the externally ionized gas volume then can be used as the on/off switch element. Initial experimental studies utilized equipment inherited from electrical discharge laser experiments, in particular, the electron guns used were of the high to very-high current density cold-cathode type. This resulted in very fast switch rise times and the ability to work with gases containing sizeable amounts of attaching species,. which in turn produced rapid switch-off times. On the other hand, the energy invested in the E-beam was almost of the same order or even the same magnitude as the energy to be switched. Since with these cold-cathode type E-beams the full E-beam voltage has to be switched, usually with spark gaps, the net gain in switched energy was quite small or nonexistent. If the E-beam current density is lowered, the ratio of discharge current to E-beam current can become much larger, as was already recognized by Kovalchuk et.al. Recently a quantitative assessment of this operating regime, using experimentally and theoretically derived values for the relevant gas characteristics such as breakdown voltage and electron transport data has been made. Desired operating parameters included a current gain of up to 1000, discharge voltage of 1 to 2 kV, rise and fall times of a few microseconds, hold-off voltage to 100kV, repetition rates to hundreds of pulses/sec and a lifetime of 106 pulses or more.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1981
- Accession Number
- ADA638153
Entities
People
- P. Bletzinger
Organizations
- Wright Laboratory