Knowledge of the relative abundance and the energy distributions of various ion species produced in laser ablation plasma is essential both in the fundamental physics ground, to understand the thermalization and expansion dynamics of the plasma plume, and in the applied physics ground, to get an efficient and versatile ion source. We present measurements and analyses related to such aspects, both for plasma in free expansion and for the extracted ion bunch. In particular, we characterized the former by means of ion current measurements, employing appropriate Faraday cups and electrostatic spectrometers; as regard as the latter, we performed time-of-flight spectrometry and depth profiling of implanted substrates. The extracted bunch signal showed modulation on time-of-flight due to the presence of multiply charged ions; depth profiling by X-ray photo-electron spectroscopy also showed a maximum penetration range and a profile modulation compatible with a multi-energetic beam. In these experiments we used UV excimer lasers, at irradiance values in the range 0.1 - 10 GW/cm2, to generate plasma from Cu and Al targets. The ion beams were extracted at voltages of tens of kV, DC.
Pre- and post-extraction analyses of different charge state ion components produced in a laser ion source
BELLONI, fabio;DORIA, Domenico;LORUSSO, ANTONELLA;NASSISI, Vincenzo;
2006-01-01
Abstract
Knowledge of the relative abundance and the energy distributions of various ion species produced in laser ablation plasma is essential both in the fundamental physics ground, to understand the thermalization and expansion dynamics of the plasma plume, and in the applied physics ground, to get an efficient and versatile ion source. We present measurements and analyses related to such aspects, both for plasma in free expansion and for the extracted ion bunch. In particular, we characterized the former by means of ion current measurements, employing appropriate Faraday cups and electrostatic spectrometers; as regard as the latter, we performed time-of-flight spectrometry and depth profiling of implanted substrates. The extracted bunch signal showed modulation on time-of-flight due to the presence of multiply charged ions; depth profiling by X-ray photo-electron spectroscopy also showed a maximum penetration range and a profile modulation compatible with a multi-energetic beam. In these experiments we used UV excimer lasers, at irradiance values in the range 0.1 - 10 GW/cm2, to generate plasma from Cu and Al targets. The ion beams were extracted at voltages of tens of kV, DC.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
