Experimental Demonstration of an MW-Level P-Band Metamaterial-Inspired Klystron

Based on coherent transition radiation using metamaterials, a compact, high-power, and high-efficiency 324 MHz metamaterial-inspired klystron with the second-harmonic bunching technology was experimentally developed. Its metamaterial-loaded resonant cavity enables a reduced internal diameter of approximately 0.3 wavelength in free space. As a result, the high-frequency structure achieves the volume and weight reduction of ~66% and ~32%, respectively, compared with conventional klystrons. Hot-test results demonstrate that under the conditions of a beam voltage of 102 kV and a beam current of 49 A, the metamaterial-inspired klystron produced the saturated peak output power exceeding 2.416 MW from 323.4 to 324.3MHz, the saturated electron efficiency of over 48%, and the saturated gain of over 49 dB. In addition, the device obtained the saturated peak output power of 3 MW and electron efficiency of 53.1% at 324 MHz, 110 kV, and 51.5A. The 48-hour reliability test results demonstrate that the ripple of saturated peak output powers remains withinthe range of −0.5% to +6% relative to 2.5 MW. It has met the requirements of the next-generation China Spallation Neutron Source (CSNS) Linac.