527 GHz gyrotron for DNP-NMR spectroscopy

Abstract

We describe the design of a 20W, continuous wave 527 GHz gyrotron for Dynamic Nuclear Polarization (DNP) enhanced solid state Nuclear Magnetic Resonance (NMR) spectroscopy on an 800 MHz spectrometer. A 9.8 T helium-free superconducting magnet with a warm bore diameter of 76mm is planned for the gyrotron operation. The gyrotron resonator cavity is designed to operate in the TE11,3,p mode at 527 GHz which is the second harmonic (ω=2ωc) of the electron cyclotron frequency. The design is based on a diode electron gun (Vk=15 kV, Ib=190 mA) and lateral output with an internal Vlasov-type mode converter. Frequency tunability of Δf/f ≈ 0.25% is being studied around the nominal frequency of 527 GHz, with a goal of constant output power of more than 20W.