Recent Developments of RIKEN ECRISs (18 GHz ECRIS and Liquid He free SC ECRIS)
Nakagawa T., Kidera M., Kurita T.*, Higurashi Y.**, Biri S.***, Miyazawa Y., Hemmi M., Chiba T., Kageyama T., Kase M., Goto A., Yano Y.
The Institute of Physical and Chemical Research (RIKEN), Japan
*Institute of Physics, Univ. Tsukuba, Japan
**College of Science, Rikkyo University, Japan
The Riken 18 GHz ECRIS successfully supplies intense beams of highly charged heavy ions to the RIKEN accelerator complex and will be used as a source for the RIKEN RI beam factory project. The main developments in the last two years are listed below.
- The beam intensities of highly charged ions are dramatically increased with using an electrode at floating potential: e.g. 1mA of Ar8+, 300 emA of Ar11+, 200 emA of Kr15+, 12 emA of Xe30+ etc.
- We measured the bremstrahlung X-ray and plasma potential dip under the pulsed mode operation when using the electrode. We found that electrode affect on high energetic electrons and as a result, they changes the plasma potential dip to increase the beam intensities.
- We have started to construct the SC-ECRIS. One of the main features of the SC-ECRIS is to use the Gifford-McMahon refrigerator for cooling directly the solenoid coils without using liquid He. It is necessary to minimize the force which support rods receive, because the use of strong rods to hold the solenoid coils is not possible due to the small cooling power. Maximum and minimum mirror magnetic filed is 3T and 0.5 T. Maximum field strength of hexapole is 1.4 T. In addition, we plan to use two frequency plasma heating (18 and 14 GHz).
In this contribution, we present the results of beam intensities and X-ray measurement in detail. We also present the structure of the SC-ECRIS, the optimization of its size and the results of test experiments.
Presenting Author : Nakagawa T.
Presentation : Oral