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Since 1994, heavy-ion radiotherapy using carbon ions is successfully carried out with the Heavy Ion Medical Accelerator in Chiba (HIMAC) at the National Institute of Radiological Sciences (NIRS). The maximum carbon ion energy is 400MeV/n. HIMAC is dedicated to radiotherapy, but it has as a second essential task to operate as users facility. In that scope it accelerates - during evening, night and weekend- many various ion species for basic experiments in biomedical science, physics, chemistry, material science, and so on. In order to serve all HIMAC users at best, the extension of the range of ion species is an important subject in ion source development at HIMAC. A PIG ion source mainly covers lighter ions from solid materials, while the 18GHz ECR ion source (called NIRS-HEC) is producing the heavier ions. Several developments on NIRS-HEC are now in progress. Various compounds are employed for the production of metallic ions by the MIVOC technique. In order to increase the beam intensity for heavier ions, additional microwave power is applied at a lower frequency by a traveling wave tube amplifier. Results of recent developments are reported.
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