This paper summarizes the performance improvements of a 264 GHz EIO subsystem achieved over the last decade. Every characteristic, practical, and reliability aspects were considered and addressed. Newer mechanical tuning provides operation with 5 W output power across a 1 GHz frequency range. Reduced voltage ripple of the Gen-IV power supply provides RF signal with linewidth of less than 4 MHz. Available LifeExtender option has the capability to extend a cathode’s lifetime beyond three years of continuous operation. A modified water-cooling design prevents electro-etching of the miniature RF circuit, while the collector has a depression capability of up to 77%.

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.

To meet demands of DNP, sub-mm-wave radar and other THz frequency markets, CPI Canada continues the performance improvements of CW and pulsed compact EIKs. The novel model of a 266 GHz oscillator generates up to 15 W of CW power, while the expected power of a 264 GHz pulsed amplifier currently in fabrication is 50 W. Together with power enhancements, major attention is paid to reliability, lifetime and signal stability.

This paper presents recently performed at CPI Canada development of high power 263 GHz CW EIO generator for DNP enhancement and pulsed 263 GHz EIK for radar applications.

A new model of vacuum tube amplifier, designed to produce over 10 Watts at 263 GHz is in development at CPI Canada. This device uses CPI's Extended Interaction Klystron technology, which has previously demonstrated good results from 17 to 220 GHz. With recent completion of a 264 GHz CW tunable oscillator, the amplifier development will extend the demonstrated envelope for EIKs to a frequency and power useful in DNP and other mm-wave applications.