Electron swarm parameters measured using photoelectrons induced by a pulse laser

Electron swarm parameters such as drift velocity and ionization coefficient are measured using photoelectrons induced by a pulse laser. In order to measure parameters in a wide region of E / p , a pulsed dc voltage synchronized with the pulse laser is applied between electrodes with a pure configuration to keep the electric field uniform. Dynamic behavior of electrons is observed as a transient waveform of an induced current. From the analysis of the waveform, the drift velocity and the ionization coefficient in helium gas can be obtained at E / p up to 500 and 4000 V/cm·Torr, respectively. Further experiments are performed using an actual discharge tube or a gas mixture of halogen and helium. The results are discussed in comparison with those obtained with a pure configuration of electrodes.