Strong electron and ion emissions induced by a pyroelectric crystal

摘要

A novel method of high voltage pulse generation was developed, based on charging a capacitor by changing the temperature of a pyroelectric crystal. A high voltage pulse is formed when a miniature spark gap device in connection with the charging capacitor is suddenly switched on. This high voltage pulse is then used to trigger strong electron and ion emissions from a ferroelectric cathode. The developments of voltage and emission with time were compared with those when the voltage pulse was produced by an external power source, and the differences were explained as due to different electric boundary conditions, based on the surface plasma assisted emission mechanisms. Factors affecting the ferroelectric cathode emissions, such as the capacitance of the charging capacitor, the polarity of the voltage pulses being applied to the front or rear electrode of the cathode, and the shape of the front grid electrode, have been investigated. Significantly higher current and total emitted electrons were observed in the case of a negative voltage applied to the front electrode. Other emission features such as the energy of the emitted particles and density distribution were also characterised.