Charge Fraction Measurements for Heavy Particle Beams Generated by the Tandem Accelerator with MCP System

In order to expand the applied range of the heavy ion beam probe measurement on LHD, it is important to increase the probing beam current. A method of increasing the current is the improvement of charge exchange efficiency of a gas cell. The experiments were carried out on a tandem accelerator at Kobe University, 5SDH-2, because various conditions of experiments can be selected for gas species, gas pressure, and ion energy. Charge fractions of negative ion, neutral atom and the positive ions were measured by a micro channel plate or Faraday cup. Dependence of the fractions of Au−, Au0, Au+ and Au2+ on gas thickness was measured. Results were compared with prior calculations, and a solution of rate equations. The cross sections for ionizing and electron capture were calculated, and some cross sections were obtained from experiments. The dependence of charge fractions for Au0, Au+ and Au2+ on the gas thickness was well presented.