Takuya Kusaka

A precision microwaverangefinder and its application to level measurement in the steel industry

Abstract A new method has been developed for decreasing the step error in FM radar systems.In this method, two sine waves of angular frequency ω1 and ω2 are mixed to the beat signal, and the phase of the beat signal is modulated to a degree of 2π in a period of 2πl(ω1-ω2). During one modulation cycle, the zero-crossing counts of the beat signal are averaged and as a result the step error is reduced. This method has been applied in the steel industry to profile measurements of charged raw materials in the blast furnace, and to level measurements of molten steel in the converter.

Development of a focusing wiggler with trapezoid-shaped permanent magnets

Abstract A focusing wiggler with trapezoid-shaped permanent magnets has been developed for the infrared free electron laser. A numerical trajectory analysis using a measured magnetic field shows that a betatron oscillation amplitude of the electron beam with 1π mm mrad emittance can be restrained within 1 mm and the FELs gain is higher than with the conventional wiggler. The magnetic field error can be easily reduced to 0.1% by precisely adjusting each magnet gap.