198GHz 140W Pulsed EIK Subsystem

This paper presents the development and test of a 198 GHz pulsed Extended Interaction Klystron (EIK) subsystem for THz markets including Dynamic Nuclear Polarization (DNP). The EIK amplifies a 30 mW input signal to 140 Watts with a - 3dB bandwidth of ~275 MHz. The operating cathode voltage is 17.7 kV and the cathode current is 178 mA. With electron beam transmission of 84 %, the subsystem is capable of operating with a duty cycle up to 5%. Liquid cooling is used to maintain the radio frequency (RF) signal stability required for DNP applications.