A Compact, 395 GHz Traveling Wave Tube (TWT) Amplifier for DNP-NMR and EPR Spectroscopy

Project Summary / Abstract We propose to develop a compact, cost-effective Traveling Wave Tube (TWT) amplifier at 395 GHz with 1.5 W continuous wave power and 20 GHz instantaneous bandwidth for application in Dynamic Nuclear Polarization (DNP) enhanced solid-state and solution-state NMR and Electron Paramagnetic Resonance (EPR) spectroscopy. With DNP, the inherently small signal intensities in a NMR experiment can be enhanced by up to two orders of magnitude. This significantly increased overall sensitivity will be highly beneficial for analytical applications of NMR spectroscopy as well as in the structure determination of bio-macromolecules using NMR methods. Currently, DNP is performed with either low power solid-state sources (whose output power is limited to a few mW at frequencies andgt; 300 GHz) and at low temperatures in the range of 20-30 K (to compensate for low microwave power) or with large, gyrotron systems which can generate 50 W of power. Gyrotrons are expensive and do not possess sufficient tuning bandwidth (andlt;0.1%) necessary for investigating a wide range of DNP experiments and thus require expensive sweep coils in the NMR magnets. The proposed TWT will address all the above concerns. The TWT is expected to cost less than one-fourth of the cost of a gyrotron system, provide 20 GHz of instantaneous bandwidth and will be a compact table-top system. These advantages will allow a larger number of researchers to take advantage of the sensitivity boost offered by DNP in NMR experiments. In Phase I, we will design, build and test a prototype system. The successful demonstration of such a system in Phase I will enable us to develop a commercial product in Phase II with superior performance. The technology is scalable and can be used at frequencies as high as 527 GHz (800 MHz NMR). A higher peak power version of the device will advance the state-of-the-art in high field EPR spectroscopy. As an ultimate result of this project, we expect Bridge12 to offer a commercial TWT at 395 GHz (600 MHz NMR) for DNP- NMR and EPR spectroscopy. This will greatly accelerate structure determination of bio-macromolecules of relevance to human disease research funded by NIH.Narrative The proposed research focuses on the development of a compact, cost-effective, 1.5 W Traveling Wave Tube (TWT) at 395 GHz for application in Dynamic Nuclear Polarization (DNP) enhanced solid and solution state NMR spectroscopy. DNP enhances the inherently small signal intensities observed in a NMR experiment by up to two orders of magnitude, dramatically increasing the overall sensitivity of the method and reducing the data acquisition time. This is of high interest for NMR methods for structural biology, pharmaceutical and analytical chemistry research; areas that are of significant interest to research funded by the U.S. National Institutes of Health.