A Novel Electron Gun Design Approach With an Externally Assembled Anode

In this work, a novel triode electron gun design approach is proposed. The electron gun consists of two components: 1) the cathode, which is connected to the body by a ceramic ring and is part of the vacuum tube, and 2) the modulation anode, which is installed externally on the electron gun. This innovative design offers the advantage of enabling the installation of a vacuum tube within a superconducting magnet with a small warm borehole. In particular, the vacuum tube is installed from one side of the magnet, while the anode is installed subsequently from the other side. This configuration has been optimized and demonstrated for two gyrotrons operating at frequencies of 198 and 792 GHz, specifically designed for dynamic nuclear polarization (DNP) in nuclear magnetic resonance (NMR) spectroscopy. The utilization of such a gun design can significantly simplify the design of a superconducting magnet, especially for gyrotrons operating at frequencies in the THz regime. This article discusses the various benefits and provides detailed insights into the design considerations associated with this type of electron gun.