Abstract. The radiation shielding calculations were performed for the beam experiment hall of the Proton Engineering Frontier Project (PEFP) in Korea using MCNPX code with nuclear data libraries of the ENDF-B/VII, JEFF3.1, LA150, JENDL-HE, and physics models, Bertini and Isabel built in MCNPX code. The neutron energy spectra from 6 targets (20 MeV/ 1.5 mA-Si, Cu, target, 20 MeV/ 50 uA-Si, 20 MeV/ 4.8 mA-C target, 100 MeV/ 300 uA-Si, W target, 100 MeV/ 10 uA-Si, 100 MeV/ 1.6 mA-C target) were calculated and used as radiation source terms. With these results, the concrete thickness satisfying shielding regulations in Korea was calculated for the target rooms and the building of the Beam Experiment Hall. Bertini, Isabel, JENDL/HE and LA150 nuclear data were applied to the evaluation of the proton induced neutrons. ENDF/B-VII, JEFF3.1, and JENDL/HE nuclear data were applied to the evaluation of the concrete shield.

A negative hydrogen ion source based on the transformer coupled plasma (TCP) source has been developed for 1.75 MeV tandem proton accelerator to detect underground explosives and mines. The TCP-based ion source has been designed and constructed for H− beam currents of 10 mA at the extraction voltage of 30 kV. High-density hydrogen plasmas of 1012 cm−3 are generated by 13.56 MHz radio frequency (rf) power with the threshold power of 1 kW. Negative hydrogen beam currents of up to 0.7 mA at the extraction voltage of 30 kV are extracted with the rf power of 1.5 kW. Extracted beam currents follow the magnitudes of plasma densities which can be adjusted by changing rf power and neutral gas pressure. The e/H− ratio of down to 70 has been achieved with a simple magnetic filter.

This paper presents operational data and parameters of the newest generation of polyphase resonant high voltage converter modulator (HVCM) as developed and delivered to the KAERI 100 MeV "PEFP" accelerator. The KAERI design realizes improvements from the SNS and SLAC designs. The present KAERI system operates two parallel THALES TH2089F 350 MHz klystrons with total power draw of 50 amperes at 105 kV. An additional 3 klystron system operating at 105 kV and 75 A is also being considered for the high energy sections of this accelerator. In these systems, to improve the IGBT switching performance, the HVCMs will be fitted with artificial zero-voltage-switching (ZVS) networks at turn-off. This new method of artificial ZVS should result in a 6 fold reduction of IGBT switching losses. This will improve the HCVM conversion efficiency to better than 95% at full average power, which is 500 kW for the 2 klystron system and 750 kW for the 3 klystron system. The artificial ZVS is accomplished by placing a soft switching capacitor network across the resonant boost transformer primary winding. This low loss snubber circuit reduces the dv/dt across the IGBTs at turn-off. As the transformer input busswork is extremely low inductance (<10 nH), the single network acts like it is across each IGBT collector-emitter terminal of the 4 transistor H-bridge switching network. We will review these topological improvements and the overall system as delivered to the KAERI accelerator with details of the installed operational results.

The Korea Multipurpose Accelerator Complex (KOMAC) project has been initiated to develop and build a high current proton/H− linear accelerator capable of delivering an 1 GeV cw proton beam with an intensity of 20 mA in the final stage. The major proton beam will be used for nuclear-waste transmutation, energy production, and nuclear physics experiments while utilizing the minor negative hydrogen beam for basic science research and medical therapy. A Duoplasmatron proton source for the KOMAC linear accelerator has been built at Korea Atomic Energy Research Institute. The hydrogen beam currents of up to 50 mA at the extraction voltage of 50 kV are routinely obtained. A low normalized rms emittance of 0.2 π mm mrad and a proton fraction of over 80% are obtained in this source. With the 100% duty factor of ion source operation, the arc filaments of the source have survived over 40 h. Except for the filament lifetime, the achieved parameters of the proton beam source are satisfying most requirements of the KOMAC ion source. The ion sources can extract the 10 mA nitrogen beam and 3 mA argon beam for the industrial surface modification processes.

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