Karino, Takahiro | Search NASA

DOE OSTI2020

Effect of solenoidal magnetic field on charge-state purity in laser ion source

A solenoidal magnetic field has been used to enhance the ion flux of a laser ion source. However, the dependence of the increase in ion current on the charge-state has not been clarified. In this study, to control the purity of the charge-state in the laser ion source, we investigated the effect of a solenoidal magnetic field on the charge-state distribution of ions in laser ion sources with a solenoid. The results indicate that the flux of ions with a heavier and/or lower charge-state can be increased using higher magnetic flux densities, and that each charged ion has an optimal solenoidal magnetic flux density that maximizes its flux. These results imply that it is possible to increase the purity of the desired charge-state ions by selecting a suitable solenoidal magnetic flux density.

43 PARTICLE ACCELERATORS↗

DOE OSTI2020

Evaluation method of beam instability in laser ion source using solenoid

In a laser ion source using solenoid field confinement, it is known that an ion beam becomes unstable in the certain range of a magnetic field. Although it is essential to quantify the instability when discussing the unstable region of the beam, it is difficult to evaluate the beam instability by peak current or the amount of charge because an irregular change of temporal profile occurs in addition to the shot-by-shot fluctuation of amplitude. In this study, I propose the most appropriate method to evaluate the beam instability using the difference from an average waveform. The validity of the new method was evaluated by comparing three evaluation methods (variation of maximum value, variation of integral of waveforms, and the proposed evaluation method) with the experimentally obtained waveforms with the stable and unstable regions of a solenoid field. The proposed method was verified to best represent the beam instability by laser-induced plasma.

43 PARTICLE ACCELERATORS↗