Abstract

Recent experimental observations suggest that interaction of intense laser radiation with rare gas clusters jets provides an efficient source of X-rays and highly charged, energetic particles. Concerning the generation of X-rays the most prominent examples are the observation of: (i) Xe(M) an Kr(L) shell transitions with energies E up to 5keV reported by Rhodes and coworkers [1], (ii) non-coherent soft X-rays (E<500eV) on a nanosecond timescale reported by Perry and co-workers [2], and (iii) efficient high harmonic generation from Xenon clusters reported by Ditmire et al. [3], Regarding the production of energetic particles, Ditmire et al. [5] have reported Xe^q+-ions with extremely high kinetic energies exceeding 100 keV when using 150fs pulses with intensities up to 10¹⁶W/cm². Interestingly, Snyder et al. [4] were able to detect high charge states such as Xe²⁰⁺ in a time-of-flight mass spectrometer after applying 350fs pulses at intensities of only 10¹⁵ W/cm² to mixed He-Xe expansions. In a recent study of Argon clusters we have made very similar observations in a moderate intensity regime of 10¹⁴W/cm² [6] using 30ps pulses at 1064nm. Our experimental results suggest that the underlying mechanism is efficient electron-ion collisional heating of cluster-sized nanoplasmas, similar to the interpretation proposed by Perry et al [2].

© 1997 Optical Society of America