Study on space charge effect in an electrostatic ion analyzer applied to measure laser produced ions.
The abundance of different ions produced by laser ion sources is usually analyzed by an electrostatic ion analyzer (EIA). Ion current intensities in the range of several mA/cm(2) at the position of the EIA have been achieved from the laser ion source developed by the Institute of Modern Physics; this indicates that a noticeable influence of space charge effect during the ion transmission will occur. Hence, while the parameters of the EIA or the beams are changed, such as ion species, current intensity, the ions' transmission efficiency through the EIA is different, which will result in an uncertainty in the estimation of the ions' yields. Special attention is focused on this issue in this paper. Ion's transmissions through the EIA under different circumstances are studied with simulations and experiments, the results of which are consistent with each other.
Charge state distribution analysis of Al and Pb ions from the laser ion source at IMP
A prototype laser ion source that could demonstrate the possibility of producing intense pulsed high charge state ion beams has been established with a commercial Nd:YAG laser (Emax=3 J, 1064 nm, 8–10 ns) to produce laser plasma for the research of Laser Ion Source (LIS). At the laser ion source test bench, high purity (99.998%) aluminum and lead targets have been tested for laser plasma experiment. An Electrostatic Ion Analyzer (EIA) and Electron Multiply Tube (EMT) detector were used to analyze the charge state and energy distribution of the ions produced by the laser ion source. The maximum charge states of Al12+ and Pb7+ were achieved. The results will be presented and discussed in this paper.
Electron emission from slow hollow atoms at a clean metal surface.
For impact of slow multicharged N, Ne, Ar, and I ions on clean polycrystalline gold (impact velocity 1×10 4 <υ p <15×10 4 m/s), for the first time the statistics of the resulting electron emission have been determined, from which rather precise total electron yields have been derived. From the impact-velocity dependences of yields and the shapes of electron multiplicities two different contributions to electron emission are identified, one probably being due to autoionization before surface impact and the other due to faser autoionization just at the surface or already inside the solid