Relativistic electron-beam-produced plasmas. II. Energy apportionment and plasma formation

Abstract

For pt.I see ibid., vol.19, p.761 (1986). The apportionment of the energy deposited in argon by a relativistic electron beam (REB) is studied in the context of the Continuous Slowing Down Approximation (CSDA). The deposition efficiencies of many argon states are presented, with special attention being paid to forbidden states excitations and inner-shell ionisations. Study of the processes leading to plasma formation shows the existence of two separated energy domains. For primary energies lower than 10 keV, the ionisation of argon is mainly due to direct pumping by the beam, while for higher energies the plasma is essentially produced via secondary and high-order generation cascades of electrons. Their contributions to the ionisation of the M-shell or to the excitation of the allowed states amount to about 70% and constitute the totality of the forbidden states production. The authors emphasis the fact that the cascade electrons arising from inner-shell ionisations are responsible for about 40% of the population of the various argon states.