The AECR-U History

The 14 GHz AECR ion source was originally designed in 1988 [C.M. Lyneis, J. Phys. (Paris) Colloq. 50 (1989) CI-689], and started operation in 1990. The AECR was carefully optimized over the next five years [Z. Q. Xie and C. M. Lyneis, RSI 65 (1991) 2947, Z. Q. Xie and C. M. Lyneis, Proceedings of the 11^th International Workshop on ECR Ion Sources, KFA, Groningen, Netherlands, 24 (1993), RSI 65 (1994) 2947]. Several ECR ion source techniques (tricks) have been developed in the AECR, including wall coatings (SiO2 and Al₂O₃) and cold electron injection.

It could be demonstrated that a plasma chamber surface with a high yield of secondary electrons, such as SiO2 and Al2O3 substantially enhance the ion source performance. In May 1990 an electron gun was added, which injects cold electrons into the plasma. This enhanced the performance significantly and was a proof that the first plasma stage is mainly a cold electron source for the main plasma stage.

A biased disk later replaced the electron gun. In 1994 the ion source was modified so that both 14 and 10 GHz microwaves could be injected and the double frequency heating effect was first demonstrated [Z. Q. Xie and C. M. Lyneis, Proceedings of the 12^th International Workshop on ECR Ion Sources, RIKEN, Japan, 24 (1995)].

Fig.1: Dan Xie with the new solenoid magnets for the AECR-U.
(click figure for enlarged picture)

In 1996 the AECR was substantially upgraded by increasing its magnetic field to improve the plasma confinement. [Z. Q. Xie and C. M. Lyneis, Proceedings of the 13^th International Workshop on ECR Ion Sources, Texas A&M, College Station, USA, 16 (1997), Z. Q. Xie and C. M. Lyneis, RSI 69 (1998)].

Since then the AECR-U continues to produce record high charge states.