ELECTRON-CYCLOTRON-RESONANCE SOURCES - HISTORICAL REVIEW AND FUTURE-PROSPECTS (INVITED)

Low charge state electron cyclotron resonance ion source (ECRIS) work since 1965 and high charge state ECRIS since 1974. These ECR sources a re categorized into three main sections: (1) Low charged ion (ECRIS) i nside simple magnetic mirror or Bucket configurations. (2) High charge d ion ECRIS inside min-B mirror configurations. (3) Short pulsed ECRIS with highly charged ions where the ion confinement is disturbed for a short while, which allows the extraction of intense ion pulses. Futur e prospects are based on rational scaling of the magnetic confinement including high B modes, by increasing the radio frequency (rf) frequen cy and ECR magnetic field. In this case, charge exchange has to be min imized and plasma instabilities have to be avoided. However, clever em pirical tricks lead also to outstanding nor always predicted improveme nts. Let us cite: optimized rf plasma coupling, electron guns, gas mix ing, wall coating, biased electrodes, and more recently multiple ECR f requency heating. ECRIS have not yet achieved their optimal possibilit ies. Let us wait for the next generation of superconducting ECRIS and the possible use of subcentimeter waves. (C) 1998 American Institute o f Physics. [S0034-6748(98)52502-6].