Second harmonic operation at 460 GHz and broadband continuous frequency tuning of a gyrotron oscillator

By M. Hornstein, V. Bajaj, R. G. Griffin, K. Kreischer, I. Mastovsky, Michael A. Shapiro, J. Sirigiri, R. Temkin. IEEE Transactions on Electron Devices, 2005

201 citations recorded by the source corpus.

We report the short-pulse operation of a 460 GHz gyrotron oscillator both at the fundamental (near 230 GHz) and second harmonic (near 460 GHz) of electron cyclotron resonance. During operation in a microsecond pulse length regime with 13-kV beam voltage and 110-mA beam current, the instrument generates several watts of power in two second harmonic modes, the TE/sub 2,6,1/ at 456.15 GHz and the TE/sub 0,6,1/ at 458.56 GHz. Operation in the fundamental modes, including the TE/sub 0,3,1/ mode at 237.91 GHz and the TE/sub 2,3,1/ at 233.15 GHz, is observed at output powers up to 70 W. Further, we demonstrate broadband continuous frequency tuning of the fundamental modes of the oscillator over a range of more than 2 GHz through variation of the magnetic field alone. We interpret these results in terms of smooth transitions between higher order axial modes of the resonator. The 460 GHz gyrotron is currently being processed for continuous duty operation, where it will serve as a microwave source for sensitivity-enhanced nuclear magnetic resonance (dynamic nuclear polarization) studies at 16 T (700 MHz /sup 1/H), a field strength which is two-fold higher than has been accessible with previous technology.

Subfields: Aerospace Engineering, Atomic and Molecular Physics, and Optics, Control and Systems Engineering

View Paper: https://www.semanticscholar.org/paper/fafbddf2e2e159d91890e6447cf1bd84dcdc520f

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Citations in the corpus

Operation of a Continuously Frequency-Tunable Second-Harmonic CW 330-GHz Gyrotron for Dynamic Nuclear Polarization (2011, methodology): “This tuning scheme was demonstrated in a millimeter-wave gyrotron operating in the first harmonic of the electron cyclotron frequency, both in pulsed mode [10] and in CW mode [11], and later in a second-harmonic CW terahertz gyrotron [12], [13].”
Vacuum Electronic High Power Terahertz Sources (2011, background): “Suitable gyrotrons producing tens of watts of output power have now been built at 250 GHz [108], 260 GHz [109], 263 GHz [110], 330 GHz [111], 395 GHz [112] and 460 GHz [113], [114].”
Technology, Capabilities, and Performance of Low Power Terahertz Sources (2011, background): “this area has shown many promising results using regenerative TWTs at 670 GHz [46], [47].”
State-of-the-Art of High-Power Gyro-Devices and Free Electron Masers (2020, background): “This work reports on the status and future prospects of gyrotron oscillators and RF vacuum windows for ECRH and ECR plasma sources for generation of multi-charged ions and soft Xrays [103-110] (Tables II-XII), the development of very high frequency gyromonotrons for active plasma diagnostics [111-14”
A Review on the Applications of High Power, High Frequency Microwave Source: Gyrotron (2011, methodology): “The gyrotrons with the frequency output of 250 GHz, 460 GHz have been developed successfully at MIT, USA for the DNP-NMR applications [93, 129 ].”
State-of-the-Art of High Power Gyro-Devices and Free Electron Masers Update 2008 (2009, background): “014 THz (TE4,12 mode, 2nd harmonic) [80-104,527-567].”