Jaegwon Yoo

A low-energy compact electron beam irradiator for core-loss reduction of silicon steel

A new compact, low-energy electron beam irradiator has been developed. The core loss of silicon steels can be reduced by the magnetic-domain refinement method. The irradiator was developed for the application of core-loss reduction using the method. The beam energy of the irradiator can be varied from 35 to 80 keV and the maximum current is 3 mA. The irradiation area is designed to be 30/spl times/30 mm/sup 2/ now and will be upgraded to 30/spl times/150 mm/sup 2/ using a scanning magnet and scanning cone. The electron beam generated from 3 mm diameter LaB/sub 6/ is extracted to the air for the irradiation of the silicon steels in the air. A special irradiation port was developed for this low-energy irradiator. A havar foil with 4.08 /spl mu/m thickness were used for the window and a cold air-cooling system keeps the foil structure by removing heat at the window. The irradiator system and its operation characteristics are discussed.

Compact free-electron laser operating in the wavelength range of 0.1-1 mm

A compact FIR FEL driven by a magnetron based microtron has been upgraded to extend the wavelength range from 0.1-0.16 mm to reach 1 mm. The energy of the electron beam from the microtron can be varied from 6.5 to 4.3 MeV by changing the position of an RF cavity inside the microtron. The resonant wavelength of the FEL is determined by the dispersion relation of the waveguide and beam line. The wavelength of the FEL with the tunable energy of the electron beam can cover an extremely wide range of the wavelength from 0.1mm to more than 1 mm.