First results with a modified multipole structure electron cyclotron resonance ion source

The radial magnetic-field strength is a critical parameter that affects the performance of an electron cyclotron resonance ion source (ECRIS). A method, known as the modified multipole structure (MMPS), for increasing the radial magnetic-field strengths has been developed and tested at the Department of Physics, University of Jyvaeskylae (JYFL). In this structure, the magnetic field is increased only at locations where the plasma flux hits the plasma chamber wall. The MMPS plasma chamber has been designed, constructed, and installed into the JYFL 6.4 GHz ECRIS. Measurements have shown that the MMPS is especially effective for increasing the production of highly charged ions. Typically, the ion current increases by a factor of 2-3 in the case of highly charged ions such as Ar16+. The first results using the technique are presented in this article