Investigation On Characteristics Of Ablation Plasma Induced By Intense Pulsed Ion Beam

It is known that intense pulsed ion beam (IPIB) have a high viability to be used as an efficient energetic source for rapid film deposition and direct surface modification. Up to now, however, there is still lack of a systematic work to reveal the influence of IPIB on the film deposition and material modification although there are lots of papers have been published in the field. In the present work, the characteristics of ablation plasma induced by IPIB are all investigated in detail.The application of ablation plasma induced by IPIB is an important aspect of IPIB industrial applications, especially on film deposition and ultrafine nano-powder production. Therefore, it has significance on theoretical and experimental investigation of the characteristics of ablation plasma, which is benefit on the development of IPIB technology.Since the fast interaction process of IPIB and solid target, we firstly diagnosticate the characteristics of ablation plasma using temporally resolved emission spectroscopy. We present the research on the optical emission spectra (OES) of the ablation plasma induced on the surface of a polyethylene target by IPIB produced in the TEMP-II accelerator of our laboratory. It can be verified from the OES that the ablation plasma is mainly composed of H, C, C2, CH species, and so on. The temporal profiles of some spectral lines of the species, recorded by a SP305 spectrometer with a TEKTRONIX TDS3052 500MHz storage oscilloscope, are investigated under the typical running conditions of the TEMP-II.The average standing time of the ablation plasma is evaluated from the temporal profiles to be 30 μ s when the IPIB has a energy density of 4J/cm~2 and a duration of 75ns. The forming time of the ablation plasma is also about 30 μ s, which equals to the average delay of the spectral emission pulses relative to the trigger pulse of the IPIB. The area covered by peaks in the waveforms of the chosen spectral emissions can be regarded proportional to the number density of the corresponding emissive species produced during ablation plasma duration. It is a temporal integral for the whole ablation plasma process, so it is a statistical average value, not an instantaneous state parameter.The distinguished differences of the average arrival-time of the emission maximums to different positions are used to determine the expansion velocity of the ablation plasma. Some spectral peak emissions from different species existed in the ablation plasmas are chosen to determine the expansion velocity of the ablation plasmas by the arrival-time scheme. The...