Development of a traveling wave resonant ring of the JNC high-power, high-duty electron linac

We present experimental results for a traveling wave resonant ring in a low-duty beam test and a high-duty RF test. In the low-duty beam test, we studied the RF characteristics of the traveling wave resonant ring and measured the multiplication factor, M, and conversion efficiency, η. We obtained multiplication factors of 3.2 under no beam loading and 2.2 under a beam loading of 100 mA and these were in good agreement with calculations. A high conversion efficiency of 0.74 was achieved by using the traveling wave resonant ring. In the high-duty RF test, we measured the multiplication factor as a function of phase shifter position and temperature of the traveling wave resonant ring. From the experimental results, we calculated the variation of the phase shifter position to a temperature rise. Understanding this variation is necessary to keep the multiplication factor at the maximum for the design point 20% duty operation.