An 18 GHz ECR ion source with high-voltage extraction configuration (NIRS-HEC) has been developed for the Heavy Ion Medical Accelerator in Chiba (HIMAC), National Institute of Radiological Sciences (NIRS). NIRS-HEC has a high extraction voltage of up to 60 kV in order to reduce the unwanted space charge effects at the extraction region. NIRS-HEC also has a strong magnetic field. A radial size of the plasma chamber is made as small as 40 mm, so that a sextupole field strength of 11 kG and an axial field strength of 12 kG are easily obtained. The experimental data show that a high extraction voltage is effective to realize the high beam intensity when the extraction current density is high. It is consistent with the computer calculations of the FUGUN code and TRAPCAD code.

Topics
Magnetic fields, Radiation therapy equipment, Ion source
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© 1998 American Institute of Physics.
1998
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