Development of continuously frequency tunable gyrotron and its application to 200 MHz DNP-NMR spectroscopy as a radiation source

The gyrotron, Gyrotron FU CW IV continues to produce output radiation in the wide range of magnetic fields from 4.9 T to 5.2 T, and continuous frequency tuning in 6 GHz interval from 134 GHz to 140 GHz can be realized. This type of gyrotron will play an important role as a high power radiation source with the function of continuous frequency tuning to the applications in the fields of millimeter to sub-millimeter wavelength range. A sensitive NMR spectroscopy using a dynamic nuclear polarization (DNP-NMR) is the versatile analytical technique to enhance the sensitivity of the NMR spectroscopy. It is well known that the enhancement of the NMR sensitivity depends strongly on the frequency of the irradiating electromagnetic wave. This gyrotron will be applied to 200 MHz DNP-NMR spectroscopy for analysis of polymer surface. Another continuous frequency tuning range (131 GHz-132.5 GHz) realized by this gyrotron covers that of the DNP-NMR spectroscopy with high performance.