Highly Charged Ions Produced by a Laser Ion Source at Institute of Modern Physics

A laser ion source using a Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser has been being under intensive study at Institute of Modern Physics (IMP) for highly charged ion productions, which is one of the crucial parts of the High Intensity heavy ion Accelerator Facility (HIAF) project. Recently several kinds of elements have been tested (C, Al, Ni, Ti, and Pb) on the laser ion source. The ions' energy in the laser produced plasma is from several kilo electron volts to tens of kilo electron volts. The maximum charge states achieved from those targets are C6+, Al12+, Ti16+, Ni19+ and Pb10+, respectively. Among these ion species, the current proportion of C6+ in the laser produced carbon plasma is up to over 30% with a laser power density about 10(12) watts per square centimeter on the target. Therefore the carbon ion beam intensity produced with the laser ion source is high enough for the cancer therapy purpose. As to other elements, the generation of high charge state ions needs optimizing. Charge state distributions (CSD) and current intensities of C, Al, Ti, Ni and Pb are presented in this paper. Besides the current intensity and CSD, another key parameter of a laser ion source is the repeatability and stability, so the statistics of Ni ion beam with 200 shots is exhibited as well.