Cyclotron Internal Ion Source with DC Extraction

This paper describes a method for increasing the intensities for heavy ion beams accelerated in isochronous cyclotrons at high harmonics (h¿5) of the orbit frequency. Normally, only small intensities are obtained at high harmonics because of the low effective accelerating voltage between the ion source and the puller electrode. We have developed and tested a dc ion extraction system for the Oak Ridge Isochronous Cyclotron (ORIC). Use of the dc extraction system has increased beams of 4OAr3+ on the 5th harmonic and 2ONel+ on the 7th harmonic from nanoamperes to microamperes.