Operation of a step tunable megawatt gyrotron

An electron cyclotron resonance maser; gyrotron fundamental oscillator; advantages of gyrotrons; a schematic of the experiment; gyrotron design theory; 1 MW design parameters; compact ignition tokamak; and a gyrotron with quasi-optical output coupler are briefly presented. This presentation is represented by viewgraphs only

High frequency gyrotrons and their application to tokamak plasma heating

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1981.MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.Includes bibliographical references.by Kenneth Edmund Kreischer.Ph.D

Dynamic nuclear polarization at 9 T using a novel 250 GHz gyrotron microwave source

In this communication, we report enhancements of nuclear spin polarization by dynamic nuclear polarization (DNP) in static and spinning solids at a magnetic field strength of 9 T (250 GHz for g = 2 electrons, 380 MHz for [superscript 1]H). In these experiments, [superscript 1]H enhancements of up to 170 ± 50 have been observed in 1-[superscript 13]C-glycine dispersed in a 60:40 glycerol/water matrix at temperatures of 20 K; in addition, we have observed significant enhancements in [superscript 15]N spectra of unoriented pf1-bacteriophage. Finally, enhancements of ~17 have been obtained in two-dimensional [superscript 13]C–[superscript 13]C chemical shift correlation spectra of the amino acid U–[superscript 13]C, [superscript 15]N-proline during magic angle spinning (MAS), demonstrating the stability of the DNP experiment for sustained acquisition and for quantitative experiments incorporating dipolar recoupling. In all cases, we have exploited the thermal mixing DNP mechanism with the nitroxide radical 4-amino-TEMPO as the paramagnetic dopant. These are the highest frequency DNP experiments performed to date and indicate that significant signal enhancements can be realized using the thermal mixing mechanism even at elevated magnetic fields. In large measure, this is due to the high microwave power output of the 250 GHz gyrotron oscillator used in these experiments.Natural Sciences and Engineering Research Council of Canada (Postgraduate Scholarship Fellowship)National Institutes of Health (U.S.) (Grant GM-35382)National Institutes of Health (U.S.) (Grant GM-55327)National Institutes of Health (U.S.) (Grant RR-00995

Final report for the tunable driver for the LLNL FEL experiment

This section of the report covers the recent operation of the prototype backward-wave oscillator (BWO) gyrotron. The tube was mounted in its fixture on the superconducting magnet, the beam aligned, and microwaves generated. Initial alignment and operation was performed at low wiggler magnet strength (B{sub w} = 9 G) and thus low {alpha} = {upsilon} {perpendicular}/{upsilon}{parallel}. The microwaves observed under these conditions were at a frequency just above the electron cyclotron frequency of the interaction region. Identification of these waves is tentatively that of forward waves generated in what is a very long gyrotron cavity. By increasing the wiggler field to {approx} 18 G, the backward wave could then be observed. Voltage tunability of the backward wave was demonstrated and frequencies from 13 GHz to 143 GHz were observed

Low emittance electron beam formation with a 17 GHz RF gun

We report on electron beam quality measurement results from the Massachusetts Institute of Technology 17 GHz RF gun experiment. The 1.5 cell RF gun uses a solenoid for emittance compensation. It has produced bunch charges up to 0.1 nC with beam energies up to 1 MeV. The normalized rms emittance of the beam after 35 cm of transport from the gun has been measured by a slit technique to be 3π mm mrad for a 50 pC bunch. This agrees well with PARMELA simulations at these beam energies. At the exit of the electron gun, we estimate the emittance to be about 1π mm mrad, which corresponds to a beam brightness of about 80 A/(π mm mrad)^{2}. Improved beam quality should be possible with a higher energy output electron beam from the gun