Effect of Solenoidal Magnetic Field on Time Evolution of Ion Beam Emittance in Laser Ion Source

Applying a solenoidal magnetic field to a laser ion source is a method to produce a high current beam. In this study, we measured the effect of the solenoidal magnetic field on the time evolution of the ion beam emittance using the double-slit method for the laser ion source. Ablation plasma was produced by irradiating an Al target with an Nd:YAG laser. From the emittance measurements, the phase difference shown in the time evolution of the emittance ellipses increased as the ion current increased by applying a magnetic field. In addition, the emittance increased with increasing time range for the averaged current in the waveform. However, the emittance using the averaged current in a pulse was almost constant with the magnetic field. These results indicate that the brightness of the beam increased as the ion beam current increased using the solenoidal magnetic field. (C) 2022 The Japan Society of Plasma Science and Nuclear Fusion Research