Portal de Periódicos da CAPES

Double layer effects in laser-ablation plasma plumes

2000; American Physical Society; Volume: 62; Issue: 4 Linguagem: Inglês

10.1103/physreve.62.5624

1538-4519

Nadezhda M. Bulgakova, Alexander V. Bulgakov, Oleg Bobrenok,

Ion-surface interactions and analysis

Charge-collector probe measurements have been performed to elucidate ion acceleration in laser-induced plasma plumes over a range of laser fluences important for pulsed laser deposition. The fundamental (1064 nm) or second (532 nm) harmonics of a Nd:YAG laser were used for ablation. The evolution of the time-of-flight ion signal from single-peaked to double-peaked and again to single-peaked with increasing laser fluence in the range of 2-25 J/cm(2) has been followed. The analysis of the ion velocity distributions shows that increasing laser fluence results in the appearance of a portion of accelerated ions that can be recognized as an additional fast peak in the time-of-flight distribution. The dependencies of the ion signal on the target-to-collector distance, the background pressure, and the wavelength of laser radiation have been studied. The results are discussed from the viewpoint of the generation of a self-consistent ambipolar electric field (so-called double layer). The observed ion acceleration suggests that formation in the plume of a high-energetic electron tail due to absorption of laser radiation is responsible for the development of a double layer.