Design of a frequency-tunable gyrotron for DNP-enhanced NMR spectroscopy

• Main Authors: Alberti, S., Ansermet, J.-P., Avramides, K.A., Fasel, D., Hogge, J.-P., Kern, S., Lievin, C., Liu, Y., Macor, A., Pagonakis, I., Silva, M., Tran, M.Q., Tran, T.M., Wagner, D.
• Format: Conference Proceeding
• Language: English
• Subjects: Cyclotrons; Electron beams; Gyrotrons; Modular construction; Nuclear magnetic resonance; Protons; Radio frequency; Solid state circuits; Spectroscopy; Superconducting magnets
• ISSN: 2162-2027
• DOI: 10.1109/ICIMW.2009.5324906

We report on the design of a modular low-power (10-50W) high-frequency gyrotron (265-530GHz) for DNP enhanced Solid-State NMR spectroscopy. With the view of covering a wide range of frequencies, a 9.7T helium-free superconducting magnet (SCM) is planned for the gyrotron operation on either the fundamental or second harmonic of the electron cyclotron frequency. The gyrotron design is based on a triode electron gun (V k =15kV, I b =100mA, V a = 6-8kV) which is very flexible for adapting the electron beam properties to a wide variety of cavities operating at the fundamental or at the second harmonic. The gyrotron is designed for a lateral output with an internal Vlasov-type converter. The reference parameters for application of DNP-enhanced NMR spectroscopy on a 400MHz ( 1 H) spectrometer are optimized with a RF frequency tunability corresponding to twice the proton NMR frequency. The modularity of the construction of the gyrotron allows for the possibility of changing only some elements like the cavity-uptaper system in order to adapt to the wide range of NMR spectrometers existing at EPFL.