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Updated: May 12, 2026

Non-equilibrium Microwave Plasma for Efficient High Temperature Chemistry
Published on: August 1, 2017
Continuously Tunable 250 GHz Gyrotron with a Double Disk Window for DNP-NMR Spectroscopy
Sudheer Jawla1, Qing Zhe Ni, Alexander Barnes
1Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA-02139, USA.
Abstract:
In this paper, we describe the design and experimental results from the rebuild of a 250 GHz gyrotron used for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance spectroscopy on a 380 MHz spectrometer. Tuning bandwidth of approximately 2 GHz is easily achieved at a fixed magnetic field of 9.24 T and a beam current of 95 mA producing an average output power of >10 W over the entire tuning band. This tube incorporates a double disk output sapphire window in order to maximize the transmission at 250.58 GHz. DNP Signal enhancement of >125 is achieved on a 13C-Urea sample using this gyrotron.
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