title: Experimental measurement of ionization degree in diode-pumped rubidium laser gain medium.
abstract: We use optogalvanic method to measure the ionization degree in the hydrocarbon-free rubidium DPAL gain medium. The results show that the ionization degree increases as pump intensity and helium pressure increase, and presents rollover as rubidium concentration increases. A maximal ionization degree of ∼6.45×10(-6) has been obtained with pump intensity of 0.82  kW/cm2, temperature of 150°C and helium pressure of 500 Torr. Theoretical estimation shows that energy pooling is the main process rather than photoexcitation for the subsequent ionization processes.
authors.forename: Zining
authors.initials: Z
authors.lastname: Yang
authors.forename: Lei
authors.initials: L
authors.lastname: Zuo
authors.forename: Weihong
authors.initials: W
authors.lastname: Hua
authors.forename: Hongyan
authors.initials: H
authors.lastname: Wang
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Xu