Design of a 527 GHz gyrotron for DNP-NMR spectroscopy

We report on the design studies of a >;20W, continuous wave 527 GHz gyrotron for the Dynamic Nuclear Polarization (DNP) enhanced solid state Nuclear Magnetic Resonance (NMR) spectroscopy on a 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 TE_{11, 3} mode at 527 GHz which is the second harmonic (ω=2ω_c) of the electron cyclotron frequency. The design is based on a diode electron gun (V_k=15 kV, I_b=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.