Frequency-agile gyrotrons as microwave sources for DNP-NMR

Dynamic nuclear polarization (DNP) improves NMR sensitivity by orders of magnitude by transferring polarization from electron to nuclear spins. Although discovered in the 1950s, the application of DNP to magnetic fields suitable for high-resolution NMR and structural biology has been hindered by a lack of high-power microwave sources in the 140-460 GHz frequency band. To fill this technological gap, my research has focused on the design and implementation of new microwave technology. Specifically, we have overseen the design and implementation of a high-power frequency-agile 198 GHz gyrotron, which we have used to perform electron decoupling with chirped microwave pulses. I now have an extensive track record in this area. Our frequency-agile gyrotrons are critical to implementing pulsed DNP with MAS-NMR for application to biological systems; for instance, time-domain DNP will provide higher DNP enhancements in biological membranes and in cells.