Ti beam extraction from a laser plasma focused by a magnetic field of a solenoid

Abstract

Laser ion sources (LISs) have the advantages of generating plasma from various solid targets and quickly switching the ion species by changing the target. Given these features, we aimed to develop a LIS for an ion implanter that requires a wide variety of ion species. The plasma generated by the LIS diffuses three-dimensionally with a wide angular distribution, such that only a small fraction of the generated ions reaching the extraction electrode aperture is extracted as a beam. With this procedure, the beam intensity is insufficient for the implanter LIS, which uses a laser with lower energy than the conventional LIS. To obtain a higher beam intensity by increasing the number of ions reaching the beam extraction electrode aperture, a plasma transport system with a linear solenoid magnet was installed immediately after the LIS chamber to focus the plasma by a magnetic field. In the Ti plasma focusing experiment using this system, the beam intensity increased up to 6.7 times compared to that of the case without a magnetic field. This result demonstrates that plasma focusing by a magnetic field is effective for increasing the beam intensity.