Download or read book Design of a 460 Gigahertz Second Harmonic Gyrotron Oscillator for Use in Dynamic Nuclear Polarization written by Melissa Kristen Hornstein and published by . This book was released on 2001 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamic nuclear polarization (DNP) is a promising technique for sensitivity enhancement in the nuclear magnetic resonance (NMR) of biological solids. Resolution in the NMR experiment is related to the strength of the static magnetic field. For that reason, high resolution DNP NMR requires a reliable millimeter/sub-millimeter coherent source, such as a gyrotron, operating at high power levels. In this work we report the design of a gyrotron oscillator for continuous-wave operation in the TE06 modeat 460 GHz at a power level of up to 50 W to provide microwave power to a 16.4 T 700 MHz NMR system and 460 GHz EPR/DNP unit. The gyrotron design is closely modeled on a previous successful design of a 25 W, 250 GHz CW gyrotron oscillator. The present design will operate at second harmonic of the cyclotron frequency ... Second harmonic operation requires careful analysis in order to optimize the oscillator design under conditions of moderate gain, high ohmic loss, and competition from fundamental ... modes. In addition, an internal mode converter will be used. The output radiation will propagate through a window and perpendicular to the magnetic field through a cross-bore pipe in the magnet. The radiation will then travel through a transmission line to arrive at the probe used for NMR experiments. In addition, the transmission line of a 140 GHz gyrotron oscillator currently operating in DNP-NMR experiments, including an external serpentine mode converter which converts the TE01 to TE11 mode, is analyzed experimentally and theoretically.