Experiments on a 28 GHz, five cavity gyroklystron amplifier are underway. Initial hot tests show ... more Experiments on a 28 GHz, five cavity gyroklystron amplifier are underway. Initial hot tests show that the stable amplified radiation produces a peak power of 50 kW at 27.85 GHz. A strong oscillation in the output cavity with power exceeding 200 kW is measured near the amplifier operating point. A careful magnetic field tuning near 10 kG is currently underway to optimize the amplifier performance. Experimental results and comparison with numerical simulation results are presented.
Printed in Great Britain Solid State Communications, Vol. 13, pp. 1485 1489, 1973. Pergarnon Pres... more Printed in Great Britain Solid State Communications, Vol. 13, pp. 1485 1489, 1973. Pergarnon Press. FAR INFRARED ABSORPTION OF AMORPHOUS GaAs AND Ge* RW Stimets, 3. Waldman, 3. Lin and TS Changt Lowell Technological Institute, Lowell, Mass., USA and * ...
A continuous random network (CRN) consisting of 238 tetrahedrally coordinated atoms has been cons... more A continuous random network (CRN) consisting of 238 tetrahedrally coordinated atoms has been constructed so as to contain only even-membered rings. The structural properties of the model (density, bond-length distribution, bond-angle distribution, dihedral-angle distribution, radial distribution function) are in satisfactory agreement with experimental results for amorphous Ge, Si, and the III-V compounds. The present model eliminates the conflict between the Polk CRN model, which contains approximately 50% of odd-membered rings, and experimental photoemission, optical, and heat-of-crystallization results for the amorphous III-V's, which indicate the absence of a significant number of such rings. Comparison of the CRN models suggests that a determination of the experimental dihedral-angle distribution of each material is very important for a unique definition of its structure.
IEEE International Conference on Plasma Science, 1990
Summary form only given. Experimental evidence was obtained for the generation of pulsed microwav... more Summary form only given. Experimental evidence was obtained for the generation of pulsed microwave and millimeter-wave radiation in the range of 20 to above 100 GHz resulting from a beam-plasma interaction in a back-lighted thyratron or pseudospark. The device supports an intense, low-emittance electron beam and a high-density glow-mode plasma. The back-lighted thyratron and pseudospark were used as a high-current
The authors report experimental results on the production of radiation from ≈20 GHz to ≈100... more The authors report experimental results on the production of radiation from ≈20 GHz to ≈100 GHz in a pseudospark-type device. Pulsed emission of radiation occurs from a low (neutral) pressure (≈100 mtorr Ar) discharge, during the initial transient phase, as the plasma is being formed and a pulsed electron beam is temporarily present. A high-energy electron beam (15~20 keV) has
ICOPS 2000. IEEE Conference Record - Abstracts. 27th IEEE International Conference on Plasma Science (Cat. No.00CH37087), 2000
Summary form only given. A gyrotron-based spectrometer suitable for nuclear magnetic resonance (N... more Summary form only given. A gyrotron-based spectrometer suitable for nuclear magnetic resonance (NMR) studies at 380 MHz has been constructed. This spectrometer is being used to study dynamic nuclear polarization (DNP), a technique that can result in significant enhancement of the NMR signal. Signal enhancements up to forty have been measured in the 13C spectra of glycerol/water/TEMPO. An important component
2011 International Conference on Infrared, Millimeter, and Terahertz Waves, 2011
ABSTRACT We report on the design studies of a >20W, continuous wave 527 GHz gyrotron for t... more ABSTRACT We report on the design studies of a >20W, continuous wave 527 GHz gyrotron for the Dynamic Nuclear Polarization (DNP) enhanced solid state Nuclear Magnetic Resonance (NMR) spectroscopy on a 800 MHz spectrometer. A 9.8 T helium-free superconducting magnet with a warm bore diameter of 76mm is planned for the gyrotron operation. The gyrotron resonator cavity is designed to operate in the TE11, 3 mode at 527 GHz which is the second harmonic (ω=2ωc) of the electron cyclotron frequency. The design is based on a diode electron gun (Vk=15 kV, Ib=190 mA) and lateral output with an internal Vlasov-type mode converter. Frequency tunability of Δf/f ≈ 0.25% is being studied around the nominal frequency of 527 GHz, with a goal of constant output power of more than 20W.
The operation of a high-power, tunable gyrotron oscillator at wavelengths extending into the subm... more The operation of a high-power, tunable gyrotron oscillator at wavelengths extending into the submillimeter-wave regime is reported. Using a 14-T Bitter magnet, frequencies from 141 GHz (TE15,2,1 mode) up to 328 GHz (TE27,6,1 mode) have been measured. As in earlier experiments, it was possible to step tune through a sequence of TEm,p1 modes over this range. From 198 GHz to
Summary form only given. We present the design, computer simulation, and experimental results of ... more Summary form only given. We present the design, computer simulation, and experimental results of a quasi-optical mode converter for use in a 110 GHz high-power gyrotron. The particular gyrotron under test generates a right-handed TE22.6 circular waveguide mode, and is designed to produce megawatt power levels over pulse durations on the order of 5 s. This high power level provides
Experiments on a 28 GHz, five cavity gyroklystron amplifier are underway. Initial hot tests show ... more Experiments on a 28 GHz, five cavity gyroklystron amplifier are underway. Initial hot tests show that the stable amplified radiation produces a peak power of 50 kW at 27.85 GHz. A strong oscillation in the output cavity with power exceeding 200 kW is measured near the amplifier operating point. A careful magnetic field tuning near 10 kG is currently underway to optimize the amplifier performance. Experimental results and comparison with numerical simulation results are presented.
Printed in Great Britain Solid State Communications, Vol. 13, pp. 1485 1489, 1973. Pergarnon Pres... more Printed in Great Britain Solid State Communications, Vol. 13, pp. 1485 1489, 1973. Pergarnon Press. FAR INFRARED ABSORPTION OF AMORPHOUS GaAs AND Ge* RW Stimets, 3. Waldman, 3. Lin and TS Changt Lowell Technological Institute, Lowell, Mass., USA and * ...
A continuous random network (CRN) consisting of 238 tetrahedrally coordinated atoms has been cons... more A continuous random network (CRN) consisting of 238 tetrahedrally coordinated atoms has been constructed so as to contain only even-membered rings. The structural properties of the model (density, bond-length distribution, bond-angle distribution, dihedral-angle distribution, radial distribution function) are in satisfactory agreement with experimental results for amorphous Ge, Si, and the III-V compounds. The present model eliminates the conflict between the Polk CRN model, which contains approximately 50% of odd-membered rings, and experimental photoemission, optical, and heat-of-crystallization results for the amorphous III-V's, which indicate the absence of a significant number of such rings. Comparison of the CRN models suggests that a determination of the experimental dihedral-angle distribution of each material is very important for a unique definition of its structure.
IEEE International Conference on Plasma Science, 1990
Summary form only given. Experimental evidence was obtained for the generation of pulsed microwav... more Summary form only given. Experimental evidence was obtained for the generation of pulsed microwave and millimeter-wave radiation in the range of 20 to above 100 GHz resulting from a beam-plasma interaction in a back-lighted thyratron or pseudospark. The device supports an intense, low-emittance electron beam and a high-density glow-mode plasma. The back-lighted thyratron and pseudospark were used as a high-current
The authors report experimental results on the production of radiation from ≈20 GHz to ≈100... more The authors report experimental results on the production of radiation from ≈20 GHz to ≈100 GHz in a pseudospark-type device. Pulsed emission of radiation occurs from a low (neutral) pressure (≈100 mtorr Ar) discharge, during the initial transient phase, as the plasma is being formed and a pulsed electron beam is temporarily present. A high-energy electron beam (15~20 keV) has
ICOPS 2000. IEEE Conference Record - Abstracts. 27th IEEE International Conference on Plasma Science (Cat. No.00CH37087), 2000
Summary form only given. A gyrotron-based spectrometer suitable for nuclear magnetic resonance (N... more Summary form only given. A gyrotron-based spectrometer suitable for nuclear magnetic resonance (NMR) studies at 380 MHz has been constructed. This spectrometer is being used to study dynamic nuclear polarization (DNP), a technique that can result in significant enhancement of the NMR signal. Signal enhancements up to forty have been measured in the 13C spectra of glycerol/water/TEMPO. An important component
2011 International Conference on Infrared, Millimeter, and Terahertz Waves, 2011
ABSTRACT We report on the design studies of a >20W, continuous wave 527 GHz gyrotron for t... more ABSTRACT We report on the design studies of a >20W, continuous wave 527 GHz gyrotron for the Dynamic Nuclear Polarization (DNP) enhanced solid state Nuclear Magnetic Resonance (NMR) spectroscopy on a 800 MHz spectrometer. A 9.8 T helium-free superconducting magnet with a warm bore diameter of 76mm is planned for the gyrotron operation. The gyrotron resonator cavity is designed to operate in the TE11, 3 mode at 527 GHz which is the second harmonic (ω=2ωc) of the electron cyclotron frequency. The design is based on a diode electron gun (Vk=15 kV, Ib=190 mA) and lateral output with an internal Vlasov-type mode converter. Frequency tunability of Δf/f ≈ 0.25% is being studied around the nominal frequency of 527 GHz, with a goal of constant output power of more than 20W.
The operation of a high-power, tunable gyrotron oscillator at wavelengths extending into the subm... more The operation of a high-power, tunable gyrotron oscillator at wavelengths extending into the submillimeter-wave regime is reported. Using a 14-T Bitter magnet, frequencies from 141 GHz (TE15,2,1 mode) up to 328 GHz (TE27,6,1 mode) have been measured. As in earlier experiments, it was possible to step tune through a sequence of TEm,p1 modes over this range. From 198 GHz to
Summary form only given. We present the design, computer simulation, and experimental results of ... more Summary form only given. We present the design, computer simulation, and experimental results of a quasi-optical mode converter for use in a 110 GHz high-power gyrotron. The particular gyrotron under test generates a right-handed TE22.6 circular waveguide mode, and is designed to produce megawatt power levels over pulse durations on the order of 5 s. This high power level provides
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Papers by R. Temkin