Design and Modeling of a Slow-Wave 260 GHz Tripler

The extended-interaction klystron frequency multiplier with a hollow electron beam has been studied numerically as a source of subterahertz radiation with controlled phase. The designs of electrodynamic and electro-optical systems are discussed for the frequency tripler with an output frequency of 260 GHz. The simulations of electron-wave interaction take into account the electron velocity spread, beam interception by a slow-wave structure, and the space charge effects. According to simulations, a two-cavity frequency tripler fed by a 1 W input signal at 86.67 GHz can deliver a maximum output power of about 15 W at a frequency of 260 GHz with a 90 MHz bandwidth (FWHM). Such a device is aimed to pulsed methods of the dynamic nuclear polarization in nuclear magnetic resonance spectroscopy.