Nakagawa, T.

Paper	Title	Page
MOCO-B01	New 28 GHz SC-ECRIS for RIKEN RI Beam Factory Project	8
	T. Nakagawa RIKEN Nishina Center, Wako, Saitama
	For RIKEN RI beam factory project, intense beam of U beam is strongly demanded. For this reason, we started to construct the new SC-ECRIS in 2007. Before construction, we intensively studied the effect of various parameters (magnetic field gas pressure etc) on the plasma. Based on these results, we designed new RIKEN SC-ECRIS for production of 15pmicroA of U35+. The Binj, Bext and Bmin are 4, 2.2 and 2.1 T, respectively. The plasma chamber size is 15cm in diameter and 55 cm in length, respectively. Main feature of this ECRIS is that we can control the magnetic field gradient at ECR zone, size of ECR zone, and mirror ratio with wide range using 6 sets of solenoid coils. The maximum ECR zone size will be 3~4 times as large as the conventional magnetic field configuration. We use the two JT+GM refrigerators to obtain enough cooling power (~10W at 4K) when using 28GHz microwaves.　In June 2008, we make a first test experiment of the Sc-coils. In this contribution, we report the detailed design, results of the test experinet, and how to determine the magnetic field configuration and chamber size, etc, based on the basic studies of the ECR plasma.
	Slides
TUCO-D03	Study of the Dependence of ECR Ion Current on Periodic Plasma Disturbance	169
	Dr. G. S. Taki, R. K. Bhandari, D. K. Chakraborty, P. R. Sarma DAE/VECC, Calcutta A. G. Drentje KVI, Groningen T. Nakagawa RIKEN Nishina Center, Wako, Saitama P. K. Ray Bengal Engineering and Science University, Howrah
	In a recent work we observed the existence of periodic current bursts from an ECR ion source when a biased disc is used for enhancing the extracted beam current. It was concluded that the current per burst in the source remains essentially constant. When the disc bias voltage is increased, the burst frequency increases, and so does the total current. Further it was seen that the current undergoes a jump at a fixed bias potential. The current jump has been found to be proportional to the charge state. The burst frequency also shows a correlated jump. However, in the case of protons a different trend is observed. As the bias potential is increased, at a particular potential value the current suddenly decreases. In this work we have studied the periodic bursts in the proton current in order to understand the difference in the behaviour of current jump in protons and heavy ions.