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Sample records for cw 250-ghz gyrotron

  1. 250 GHz CW Gyrotron Oscillator for Dynamic Nuclear Polarization in Biological Solid State NMR

    PubMed Central

    Bajaj, Vikram S.; Hornstein, Melissa K.; Kreischer, Kenneth E.; Sirigiri, Jagadishwar R.; Woskov, Paul P.; Mak-Jurkauskas, Melody L.; Herzfeld, Judith; Temkin, Richard J.; Griffin, Robert G.

    2009-01-01

    In this paper, we describe a 250 GHz gyrotron oscillator, a critical component of an integrated system for magic angle spinning (MAS) dynamic nuclear polarization (DNP) experiments at 9T, corresponding to 380 MHz 1H frequency. The 250 GHz gyrotron is the first gyro-device designed with the goal of seamless integration with an NMR spectrometer for routine DNP-enhanced NMR spectroscopy and has operated under computer control for periods of up to 21 days with a 100% duty cycle. Following a brief historical review of the field, we present studies of the membrane protein bacteriorhodopsin (bR) using DNP-enhanced multidimensional NMR. These results include assignment of active site resonances in [U-13C,15N]-bR and demonstrate the utility of DNP for studies of membrane proteins. Next, we review the theory of gyro-devices from quantum mechanical and classical viewpoints and discuss the unique considerations that apply to gyrotron oscillators designed for DNP experiments. We then characterize the operation of the 250 GHz gyrotron in detail, including its long-term stability and controllability. We have measured the spectral purity of the gyrotron emission using both homodyne and heterodyne techniques. Radiation intensity patterns from the corrugated waveguide that delivers power to the NMR probe were measured using two new techniques to confirm pure mode content: a thermometric approach based on the temperature-dependent color of liquid crystalline media applied to a substrate and imaging with a pyroelectric camera. We next present a detailed study of the mode excitation characteristics of the gyrotron. Exploration of the operating characteristics of several fundamental modes reveals broadband continuous frequency tuning of up to 1.8 GHz as a function of the magnetic field alone, a feature that may be exploited in future tunable gyrotron designs. Oscillation of the 250 GHz gyrotron at the second harmonic of cyclotron resonance begins at extremely low beam currents (as low

  2. 250 GHz CW gyrotron oscillator for dynamic nuclear polarization in biological solid state NMR

    NASA Astrophysics Data System (ADS)

    Bajaj, Vikram S.; Hornstein, Melissa K.; Kreischer, Kenneth E.; Sirigiri, Jagadishwar R.; Woskov, Paul P.; Mak-Jurkauskas, Melody L.; Herzfeld, Judith; Temkin, Richard J.; Griffin, Robert G.

    2007-12-01

    In this paper, we describe a 250 GHz gyrotron oscillator, a critical component of an integrated system for magic angle spinning (MAS) dynamic nuclear polarization (DNP) experiments at 9 T, corresponding to 380 MHz 1H frequency. The 250 GHz gyrotron is the first gyro-device designed with the goal of seamless integration with an NMR spectrometer for routine DNP enhanced NMR spectroscopy and has operated under computer control for periods of up to 21 days with a 100% duty cycle. Following a brief historical review of the field, we present studies of the membrane protein bacteriorhodopsin (bR) using DNP enhanced multidimensional NMR. These results include assignment of active site resonances in [U- 13C, 15N]-bR and demonstrate the utility of DNP for studies of membrane proteins. Next, we review the theory of gyro-devices from quantum mechanical and classical viewpoints and discuss the unique considerations that apply to gyrotron oscillators designed for DNP experiments. We then characterize the operation of the 250 GHz gyrotron in detail, including its long-term stability and controllability. We have measured the spectral purity of the gyrotron emission using both homodyne and heterodyne techniques. Radiation intensity patterns from the corrugated waveguide that delivers power to the NMR probe were measured using two new techniques to confirm pure mode content: a thermometric approach based on the temperature-dependent color of liquid crystalline media applied to a substrate and imaging with a pyroelectric camera. We next present a detailed study of the mode excitation characteristics of the gyrotron. Exploration of the operating characteristics of several fundamental modes reveals broadband continuous frequency tuning of up to 1.8 GHz as a function of the magnetic field alone, a feature that may be exploited in future tunable gyrotron designs. Oscillation of the 250 GHz gyrotron at the second harmonic of cyclotron resonance begins at extremely low beam currents (as

  3. Corrugated Waveguide and Directional Coupler for CW 250-GHz Gyrotron DNP Experiments

    PubMed Central

    Woskov, Paul P.; Bajaj, Vikram S.; Hornstein, Melissa K.; Temkin, Richard J.; Griffin, Robert G.

    2007-01-01

    A 250-GHz corrugated transmission line with a directional coupler for forward and backward power monitoring has been constructed and tested for use with a 25-W continuous-wave gyrotron for dynamic nuclear polarization (DNP) experiments. The main corrugated line (22-mm internal diameter, 2.4-m long) connects the gyrotron output to the DNP probe input. The directional coupler, inserted approximately midway, is a four-port crossed waveguide beamsplitter design. Two beamsplitters, a quartz plate and ten-wire array, were tested with output coupling of 2.5% (−16 dB) at 250.6 GHz and 1.6% (−18 dB), respectively. A pair of mirrors in the DNP probe transferred the gyrotron beam from the 22-mm waveguide to an 8-mm helically corrugated waveguide for transmission through the final 0.58-m distance inside the NMR magnet to the sample. The transmission-line components were all cold tested with a 248 ± 4-GHz radiometer. A total insertion loss of 0.8 dB was achieved for HE11 -mode propagation from the gyrotron to the sample with only 1% insertion loss for the 22-mm-diameter waveguide. A clean Gaussian gyrotron beam at the waveguide output and reliable forward power monitoring were achieved for many hours of continuous operation. PMID:17901907

  4. Continuously Tunable 250 GHz Gyrotron with a Double Disk Window for DNP-NMR Spectroscopy

    PubMed Central

    Jawla, Sudheer; Ni, Qing Zhe; Barnes, Alexander; Guss, William; Daviso, Eugenio; Herzfeld, Judith; Griffin, Robert; Temkin, Richard

    2012-01-01

    In this paper, we describe the design and experimental results from the rebuild of a 250 GHz gyrotron used for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance spectroscopy on a 380 MHz spectrometer. Tuning bandwidth of approximately 2 GHz is easily achieved at a fixed magnetic field of 9.24 T and a beam current of 95 mA producing an average output power of >10 W over the entire tuning band. This tube incorporates a double disk output sapphire window in order to maximize the transmission at 250.58 GHz. DNP Signal enhancement of >125 is achieved on a 13C-Urea sample using this gyrotron. PMID:23539422

  5. Continuously Tunable 250 GHz Gyrotron with a Double Disk Window for DNP-NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Jawla, Sudheer; Ni, Qing Zhe; Barnes, Alexander; Guss, William; Daviso, Eugenio; Herzfeld, Judith; Griffin, Robert; Temkin, Richard

    2013-01-01

    In this paper, we describe the design and experimental results from the rebuild of a 250 GHz gyrotron used for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance spectroscopy on a 380 MHz spectrometer. Tuning bandwidth of approximately 2 GHz is easily achieved at a fixed magnetic field of 9.24 T and a beam current of 95 mA producing an average output power of >10 W over the entire tuning band. This tube incorporates a double disk output sapphire window in order to maximize the transmission at 250.58 GHz. DNP Signal enhancement of >125 is achieved on a 13C-Urea sample using this gyrotron.

  6. Continuously Tunable 250 GHz Gyrotron with a Double Disk Window for DNP-NMR Spectroscopy.

    PubMed

    Jawla, Sudheer; Ni, Qing Zhe; Barnes, Alexander; Guss, William; Daviso, Eugenio; Herzfeld, Judith; Griffin, Robert; Temkin, Richard

    2013-01-01

    In this paper, we describe the design and experimental results from the rebuild of a 250 GHz gyrotron used for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance spectroscopy on a 380 MHz spectrometer. Tuning bandwidth of approximately 2 GHz is easily achieved at a fixed magnetic field of 9.24 T and a beam current of 95 mA producing an average output power of >10 W over the entire tuning band. This tube incorporates a double disk output sapphire window in order to maximize the transmission at 250.58 GHz. DNP Signal enhancement of >125 is achieved on a (13)C-Urea sample using this gyrotron.

  7. A 250 GHz Gyrotron with a 3 GHz Tuning Bandwidth for Dynamic Nuclear Polarization

    PubMed Central

    Barnes, Alexander B.; Nanni, Emilio A.; Herzfeld, Judith; Griffin, Robert G.; Temkin, Richard J.

    2012-01-01

    We describe the design and implementation of a novel tunable 250 GHz gyrotron oscillator with >10 W output power over most of a 3 GHz band and >35 W peak power. The tuning bandwidth and power are sufficient to generate a >1 MHz nutation frequency across the entire nitroxide EPR lineshape for cross effect DNP, as well as to excite solid effect transitions utilizing other radicals, without the need for sweeping the NMR magnetic field. Substantially improved tunability is achieved by implementing a long (23 mm) interaction cavity that can excite higher order axial modes by changing either the magnetic field of the gyrotron or the cathode potential. This interaction cavity excites the rotating TE5,2,q mode, and an internal mode converter outputs a high-quality microwave beam with >94% Gaussian content. The gyrotron was integrated into a DNP spectrometer, resulting in a measured DNP enhancement of 54 on the membrane protein bacteriorhodopsin. PMID:22743211

  8. A 250 GHz gyrotron with a 3 GHz tuning bandwidth for dynamic nuclear polarization.

    PubMed

    Barnes, Alexander B; Nanni, Emilio A; Herzfeld, Judith; Griffin, Robert G; Temkin, Richard J

    2012-08-01

    We describe the design and implementation of a novel tunable 250 GHz gyrotron oscillator with >10 W output power over most of a 3 GHz band and >35 W peak power. The tuning bandwidth and power are sufficient to generate a >1 MHz nutation frequency across the entire nitroxide EPR lineshape for cross effect DNP, as well as to excite solid effect transitions utilizing other radicals, without the need for sweeping the NMR magnetic field. Substantially improved tunability is achieved by implementing a long (23 mm) interaction cavity that can excite higher order axial modes by changing either the magnetic field of the gyrotron or the cathode potential. This interaction cavity excites the rotating TE(₅,₂,q) mode, and an internal mode converter outputs a high-quality microwave beam with >94% Gaussian content. The gyrotron was integrated into a DNP spectrometer, resulting in a measured DNP enhancement of 54 on the membrane protein bacteriorhodopsin.

  9. A 250 GHz gyrotron with a 3 GHz tuning bandwidth for dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Barnes, Alexander B.; Nanni, Emilio A.; Herzfeld, Judith; Griffin, Robert G.; Temkin, Richard J.

    2012-08-01

    We describe the design and implementation of a novel tunable 250 GHz gyrotron oscillator with >10 W output power over most of a 3 GHz band and >35 W peak power. The tuning bandwidth and power are sufficient to generate a >1 MHz nutation frequency across the entire nitroxide EPR lineshape for cross effect DNP, as well as to excite solid effect transitions utilizing other radicals, without the need for sweeping the NMR magnetic field. Substantially improved tunability is achieved by implementing a long (23 mm) interaction cavity that can excite higher order axial modes by changing either the magnetic field of the gyrotron or the cathode potential. This interaction cavity excites the rotating TE5,2,q mode, and an internal mode converter outputs a high-quality microwave beam with >94% Gaussian content. The gyrotron was integrated into a DNP spectrometer, resulting in a measured DNP enhancement of 54 on the membrane protein bacteriorhodopsin.

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

    NASA Astrophysics Data System (ADS)

    Bajaj, V. S.; Farrar, C. T.; Hornstein, M. K.; Mastovsky, I.; Vieregg, J.; Bryant, J.; Eléna, B.; Kreischer, K. E.; Temkin, R. J.; Griffin, R. G.

    2011-12-01

    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 1H). In these experiments, 1H enhancements of up to 170 ± 50 have been observed in 1- 13C-glycine dispersed in a 60:40 glycerol/water matrix at temperatures of 20 K; in addition, we have observed significant enhancements in 15N spectra of unoriented pf1-bacteriophage. Finally, enhancements of ˜17 have been obtained in two-dimensional 13C- 13C chemical shift correlation spectra of the amino acid U- 13C, 15N-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.

  11. Development of second harmonic gyrotrons, Gyrotron FU CW GII and Gyrotron FU CW GIII, equipped with internal mode converters

    NASA Astrophysics Data System (ADS)

    Tatematsu, Yoshinori; Yamaguchi, Yuusuke; Idehara, Toshitaka; Kawase, Tatsuru; Ichioka, Ryoichi; Ogawa, Isamu; Saito, Teruo; Fujiwara, Toshimichi

    2014-01-01

    Second harmonic gyrotrons, Gyrotron FU CW GII and Gyrotron FU CW GIII, were developed at the Research Center for Development of Far-Infrared Region, University of Fukui, Japan to achieve two goals. Each gyrotron was equipped with an internal quasi-optical mode converter. Using Gyrotron FU CW GII allowed the design of the cavity and mode converter to be validated, which was the first goal. After that, Gyrotron FU CW GIII, which is an improved version of Gyrotron FU CW GII, allowed us to achieve a high power output of up to 420 W, which was the second goal, with a cathode voltage setting of -21 kV and a beam current of 0.57 A. This was achieved using a newly developed electron gun and with the careful sitting of the gyrotron on the magnet.

  12. 2 MW CW RF load for gyrotrons

    SciTech Connect

    Lawrence Ives, R.; Marsden, David; Mizuhara, Max; Collins, George; Neilson, Jeff; Borchard, Philipp

    2011-07-01

    Final design and assembly are in progress for a 2MW CW RF load for gyrotrons. Such loads are required for testing high power gyrotrons for electron cyclotron heating of fusion plasmas. The research is building on experience with a 1 MW load to increase the power capability, reduce backscattered RF power, and improve the mechanical design. (author)

  13. 100 GHz, 1 MW, CW gyrotron study program. Final report

    SciTech Connect

    Felch, K.; Bier, R.; Caplan, M.; Jory, H.

    1983-09-01

    The results of a study program to investigate the feasibility of various approaches in designing a 100 GHz, 1 MW CW gyrotron are presented. A summary is given of the possible configurations for a high average power, high frequency gyrotron, including an historical survey of experimental results which are relevant to the various approaches. A set of basic scaling considerations which enable qualitative comparisons between particular gyrotron interaction circuits is presented. These calculations are important in understanding the role of various electron beam and circuit parameters in achieving a viable gyrotron design. Following these scaling exercises, a series of design calculations is presented for a possible approach in achieving 100 GHz, 1 MW CW. These calculations include analyses of the electron gun and interaction circuit parts of the gyrotron, and a general analysis of other aspects of a high average power, high frequency gyrotron. Scalability of important aspects of the design to other frequencies is also discussed, as well as key technology issues.

  14. Development of 1 to 1.5 MW CW Gyrotrons

    NASA Astrophysics Data System (ADS)

    Felch, K.; Blank, M.; Borchard, P.; Cahalan, P.; Cauffman, S.; Chu, S.; Jory, H.

    2003-10-01

    High power mm-wave sources provide electron cyclotron heating, current drive, and instability suppression in fusion plasmas. CPI has delivered three 110 GHz, 1 MW gyrotrons for ECH and ECCD experiments on DIII-D, each of which has demonstrated reliable operation at 1 MW for pulse lengths up to 5 seconds. CPI has also delivered a 140 GHz, 1 MW gyrotron to IPP for use on W-7X. This gyrotron has produced a peak output power of 900 kW, and pulse lengths up to 700 seconds at 500 kW. Ten consecutive 500 kW 600 second pulses were demonstrated without fault at 25CPI's test facilities could not support long pulse operation at full power, such operation is planned at IPP. The 140 GHz system employs a diode magnetron injection gun, a TE_28,7 cavity interaction mode, an internal mode converter to produce a Gaussian output beam, a low-loss CVD diamond output window, and a single-stage depressed-voltage beam collector to enhance the overall electrical efficiency of the device. Currently, under a DOE development program, CPI is fabricating a 110 GHz, 1.3-1.5 MW CW depressed-collector gyrotron to deliver improved reliability at power levels above 1 MW.

  15. Analysis of Aftercavity Interaction in European ITER Gyrotrons and in the Compact Sub-THz Gyrotron FU CW-CI

    NASA Astrophysics Data System (ADS)

    Dumbrajs, Olgierd; Idehara, Toshitaka

    2012-12-01

    Possibilities of arising of aftercavity interaction are analyzed in the ITER 170 GHz 2 MW coaxial cavity gyrotron and the 170 GHz 1 MW cylindrical cavity gyrotron, as well as in the compact 394.5 GHz low power gyrotron FU CW-CI. Also, the simulations for the gyrotron efficiency in the presence of aftercavity interaction are performed in the cold cavity approximation. Results of the analysis illustrate the subtle interplay between the geometry of the output taper and the profile of the magnetic field.

  16. Gyrotron FU CW VII for 300 MHz and 600 MHz DNP-NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Idehara, Toshitaka; Kosuga, Kosuke; Agusu, La; Ogawa, Isamu; Takahashi, Hiroki; Smith, Mark E.; Dupree, Ray

    2010-07-01

    Gyrotron FU CW VII, one of the FU CW Series Gyrotrons, has been designed, constructed and completed operational tests successfully in the Research Center for Development of Far Infrared Region, University of Fukui (FIR FU). The gyrotron operates at around 200 GHz for the fundamental cyclotron resonances and at around 400 GHz for the second harmonics. These radiation frequencies will be applied to 300 MHz and 600 MHz DNP enhanced NMR spectroscopy.

  17. Design and operation of 140 GHz gyrotron oscillators for power levels up to 1 MW CW

    SciTech Connect

    Jory, H.; Bier, R.; Craig, L.J.; Felch, K.; Ives, L.; Lopez, N.; Spang, S.

    1986-12-01

    Varian has designed and tested 140 GHz gyrotron oscillators that have generated output powers of 100 kW CW and 200 kW for 1 ms pulses. Upcoming tubes will be designed to operate at power levels of 200 kW CW and ultimately up to 1 MW CW. The important design considerations which are addressed in the higher power tubes include the design of the electron gun, interaction circuit, and output window. These issues will be discussed and the results of the earlier 140 GHz gyrotron work at Varian will be summarized.

  18. Design of a 1-MW, CW coaxial gyrotron with two gaussian beam outputs

    NASA Astrophysics Data System (ADS)

    Hirata, Y.; Hayashi, K.; Mitsunaka, Y.; Itoh, Y.; Sugawara, T.

    1995-04-01

    The design of a 170 GHz, 1 MW-CW gyrotron for electron cyclotron heating of nuclear fusion plasmas is presented. The designed gyrotron incorporates a coaxial cavity to reduce mode competition, and a coaxial electron gun to support the cavity inner conductor. A new mode converter splits the generated wave into two beams and radiates them in different directions. The radiated beams are transmitted to two output windows through two mirror systems, being transformed into Gaussian-like beams. A single-stage depressed collector improves the overall efficiency of the gyrotron and reduces the heat flux to the collector surface.

  19. Continuous-wave Submillimeter-wave Gyrotrons

    PubMed Central

    Han, Seong-Tae; Griffin, Robert G.; Hu, Kan-Nian; Joo, Chan-Gyu; Joye, Colin D.; Mastovsky, Ivan; Shapiro, Michael A.; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Torrezan, Antonio C.; Woskov, Paul P.

    2007-01-01

    Recently, dynamic nuclear polarization enhanced nuclear magnetic resonance (DNP/NMR) has emerged as a powerful technique to obtain significant enhancements in spin spectra from biological samples. For DNP in modern NMR systems, a high power continuous-wave source in the submillimeter wavelength range is necessary. Gyrotrons can deliver tens of watts of CW power at submillimeter wavelengths and are well suited for use in DNP/NMR spectrometers. To date, 140 GHz and 250 GHz gyrotrons are being employed in DNP spectrometer experiments at 200 MHz and 380 MHz at MIT. A 460 GHz gyrotron, which has operated with 8 W of CW output power, will soon be installed in a 700 MHz NMR spectrometer. High power radiation with good spectral and spatial resolution from these gyrotrons should provide NMR spectrometers with high signal enhancement through DNP. Also, these tubes operating at submillimeter wavelengths should have important applications in research in physics, chemistry, biology, materials science and medicine. PMID:17404605

  20. Continuous-wave Submillimeter-wave Gyrotrons.

    PubMed

    Han, Seong-Tae; Griffin, Robert G; Hu, Kan-Nian; Joo, Chan-Gyu; Joye, Colin D; Mastovsky, Ivan; Shapiro, Michael A; Sirigiri, Jagadishwar R; Temkin, Richard J; Torrezan, Antonio C; Woskov, Paul P

    2006-01-01

    Recently, dynamic nuclear polarization enhanced nuclear magnetic resonance (DNP/NMR) has emerged as a powerful technique to obtain significant enhancements in spin spectra from biological samples. For DNP in modern NMR systems, a high power continuous-wave source in the submillimeter wavelength range is necessary. Gyrotrons can deliver tens of watts of CW power at submillimeter wavelengths and are well suited for use in DNP/NMR spectrometers. To date, 140 GHz and 250 GHz gyrotrons are being employed in DNP spectrometer experiments at 200 MHz and 380 MHz at MIT. A 460 GHz gyrotron, which has operated with 8 W of CW output power, will soon be installed in a 700 MHz NMR spectrometer. High power radiation with good spectral and spatial resolution from these gyrotrons should provide NMR spectrometers with high signal enhancement through DNP. Also, these tubes operating at submillimeter wavelengths should have important applications in research in physics, chemistry, biology, materials science and medicine.

  1. Design studies of the output system of a 95 GHz, 100 kW, CW gyrotron

    SciTech Connect

    Vamshi Krishna, P.; Kartikeyan, M.V. E-mail: kartik@iitr.ernet.in; Thumm, M.

    2011-07-01

    This paper presents the design studies of the output system of a 95 GHz, 100 kW, CW gyrotron for ECRH7ECRIS applications. During this course, the design studies of an advanced dimpled-wall quasi optical launcher, non-linear taper and RF window will be carried out. (author)

  2. CW, high power, gyrotron development at 110 GHz for ECH applications

    SciTech Connect

    Chu, T.S.; Borchard, P.; Felch, K.; Jory, H.; Loring, C.M.

    1996-12-31

    Electron cyclotron heating (ECH) is the most promising plasma heating method to achieve fusion. High-power, long-pulse or CW gyrotrons are required in many present and future ECH experiments. For example, the planned experiment at DIII-D, the experimental tokamak at General Atomics, will require 4 MW of RF power at 110 GHz for a pulse duration of 10 seconds. The RF requirement for the planned International Thermonuclear Experimental Reactor (ITER) is 50 MW at 170 GHz and CW operation. CPI is developing high-power, CW gyrotrons at frequencies ranging from 84--170 GHz for various ECH experiments. In particular, the authors are developing a 1 MW, CW gyrotron with an internal converter at 110 GHz. To achieve the goal of 1 MW, CW operation, the authors have designed and begun fabrication of a new tube that has improved cooling to all tube parts which showed signs of overheating during the last experiment. In addition, they are looking at the possibility of using alternate output window designs to increase power handling capability. They summarize the design of the new tube and present initial test data.

  3. CW, high power, gyrotron development at 110 GHz for ECH applications

    SciTech Connect

    Chu, T.S.; Borchard, P.; Felch, K.; Jory, H.; Loring, C.M.

    1996-12-31

    Electron cyclotron heating (ECH) is the most promising plasma heating method to achieve fusion. High-power, long-pulse or CW gyrotrons are required in many present and future ECH experiments. For example, the planned experiment at DIII-D, the experimental tokamak at General Atomics, will require 4 MW of RF power at 110 GHz for a pulse duration of 10 seconds. The RF requirement for the planned International Thermonuclear Experimental Reactor (ITER) is 50 MW at 170 GHz and CW operation. CPI is developing high-power, CW gyrotrons at frequencies ranging from 84--170 GHz for various ECH experiments. In particular, the authors are developing a 1 MW, CW gyrotron with an internal converter at 110 GHz. To achieve the goal of 1 MW, CW operation, they have designed and begun fabrication of a new tube that has improved cooling to all tube parts which showed signs of overheating during the last experiment. In addition, they are looking at the possibility of using alternate output window designs to increase power handling capability. They will summarize the design of the new tube and present initial test data.

  4. Mode selection and resonator design studies of a 95 GHz, 100 kW, CW gyrotron

    SciTech Connect

    Vamshi Krishna, P.; Kartikeyan, M.V. E-mail: kartik@iitr.ernet.in; Thumm, M.

    2011-07-01

    In this paper, the mode selection procedure leading to the design and the cavity resonator design studies of a 95 GHz, 100 kW, CW Gyrotron will be presented, such a gyrotron will be used for specific ECRH/ECRIS applications. In this course all the suitable modes with design constraints within the limits of design goals are considered and finally the TE{sub 10.4} mode is chosen as the operating mode which is suitable for the design. Design constraints are carefully investigated, and starting currents are computed. (author)

  5. HV-system for CW-gyrotrons at W7-X and the relevance for ITER

    NASA Astrophysics Data System (ADS)

    Braune, H.; Brand, P.; Krampitz, R.; Leonhardt, W.; Mellein, D.; Michel, G.; Mueller, G.; Sachtleben, J.; Winkler, M.; W7-X ECRH Teams at IPP IPF; FZK

    2005-01-01

    Electron Cyclotron Resonance Heating (ECRH) is the main heating method for the Wendelstein 7-X Stellarator (W7-X), which is under construction at IPP-Greifswald. A 10 MW ECRH plant with CW-capability at 140 GHz is under construction to meet the scientific objectives. The microwave power is generated by 10 gyrotrons with 1 MW each two gyrotrons are operational at IPP in Greifswald. The tubes are equipped with a single-stage depressed collector for energy recovery and operate with an output power modulation between 0.3 and 1 MW with a sinusoidal frequency of up to 10 kHz which is achieved by modulating the depression voltage and is an interesting feature for NTM control at ITER. The general features of the ECRH-plant such as frequency power, cw-capability, flexibility and the experimental experience are of high relevance for the ITER system. Each gyrotron is fed by two high-voltage sources. A high-power supply for driving the electron beam and a precision low-power supply for beam acceleration. The high-power facility consists of modular solid state HV-supplies (-65 kV 50/100 A) providing fast power control and high flexibility. The low-power high-voltage source for beam acceleration is realized by a feed back controlled high-voltage servo-amplifier driving the depression voltage. A protection system with a thyratron crowbar for fast power removal in case of gyrotron failure by arcing is installed. Both the high power and low-power high-voltage sources have the capability to supply a 2 MW ITER gyrotron without any modification. Analogue electronic devices control the fast functions of the high-voltage system for each gyrotron and a hierarchy of industrial standard PLCs and computers supervise the whole ECRH-plant.

  6. Millimeter wave, 25 kW CW gyrotrons using permanent-magnets

    SciTech Connect

    McDermott, D.B.; Luhmann, N.C. Jr.

    1996-12-31

    Two compact 25 kW cw, low magnetic field gyrotrons have been designed for use in Ka-Band and W-Band systems. Both 50 kV devices have been designed to minimize their size and weight by using a 4.5 kG Samarium cobalt permanent magnet. Their designs are presented. The 35 GHz gyrotron uses a 3 A MIG and operates at the third harmonic in the TE{sub 411} mode of a smooth-bore cylindrical cavity. For an output power of 25 kW, the predicted conversion efficiency is 25%, yielding an output efficiency of 17%. An ideal 33 kV single-stage depressed collector following a magnetic downtaper could increase the device efficiency to 50%. The 94 GHz gyrotron utilizes a Cusp gun and operates at the eight-harmonic in a sixteen-vane slotted cavity. The efficiency of the 95 GHz gyrotron is predicted to be 10%, which could also be boosted to {approximately} 50% with a depressed collector. Either device can be reconfigured as a tunable gyro-BWO. Mode competition will be controlled in both gyrotrons by slicing the cavities to interrupt the azimuthal wall currents of unwanted modes as utilized recently in the successful second-harmonic TE{sub 21} gyro-TWT amplifier experiment.

  7. Development of a Compact sub-THz Gyrotron FU CW CI for Application to High Power THz Technologies

    NASA Astrophysics Data System (ADS)

    Idehara, Toshitaka; Mudiganti, Jagadish C.; Agusu, La; Kanemaki, Tomohiro; Ogawa, Isamu; Fujiwara, Toshimichi; Matsuki, Yoh; Ueda, Keisuke

    2012-07-01

    For application of high frequency gyrotron to high power THz technology, Gyrotron FU CW series is being developed in FIR FU. Gyrotron FU CW CI is developed as one of sub-THz gyrotrons included in the series. The advantage of the gyrotron is compactness using a compact superconducting magnet and compact power supply system, which makes the accesses of the gyrotron to applied large-scale devices easier and extends the applications of gyrotron to wider fields. The designed frequency and cavity mode are 394.5 GHz and TE26 mode for application to the 600 MHz DNP-NMR spectroscopy. As the operation results, the frequency and the output power were 394.03 GHz and around 30 W, respectively, which are available for the application to the 600 MHz DNP-NMR measurement. In addition, this gyrotron can operate at many other frequencies and cavity modes for application to high power THz technologies in wide fields. In this paper, the design and the operation results including long pulse or CW mode are presented.

  8. Nd-Fe-B permanent magnet circuit for a 28 GHz CW gyrotron

    SciTech Connect

    Takada, Takeo; Ohashi, Ken; Honshima, Masakatsu; Kikunaga, Toshiyuki

    1995-12-31

    The magnetic circuit using Nd-Fe-B permanent magnets (PMs, in short) was designed and constructed for a 28 GHz CW gyrotron. The PM dimensions were calculated by an optimization algorithm in order to produce a desired axial field of 5150 G and uniformity less than 0.5 %. It was found that the measured axial field on-axis after fabricating is in a good agreement with the calculated field.

  9. Efficient Low-Voltage Operation of a CW Gyrotron Oscillator at 233 GHz

    PubMed Central

    Hornstein, Melissa K.; Bajaj, Vikram S.; Griffin, Robert G.; Temkin, Richard J.

    2007-01-01

    The gyrotron oscillator is a source of high average power millimeter-wave through terahertz radiation. In this paper, we report low beam power and high-efficiency operation of a tunable gyrotron oscillator at 233 GHz. The low-voltage operating mode provides a path to further miniaturization of the gyrotron through reduction in the size of the electron gun, power supply, collector, and cooling system, which will benefit industrial and scientific applications requiring portability. Detailed studies of low-voltage operation in the TE2,3,1 mode reveal that the mode can be excited with less than 7 W of beam power at 3.5 kV. During CW operation with 3.5-kV beam voltage and 50-mA beam current, the gyrotron generates 12 W of RF power at 233.2 GHz. The EGUN electron optics code describes the low-voltage operation of the electron gun. Using gun-operating parameters derived from EGUN simulations, we show that a linear theory adequately predicts the low experimental starting currents. PMID:17687412

  10. Design considerations in achieving 1 MW CW operation with a whispering-gallery-mode gyrotron

    SciTech Connect

    Felch, K.; Feinstein, J.; Hess, C.; Huey, H.; Jongewaard, E.; Jory, H.; Neilson, J.; Pendleton, R.; Pirkle, D.; Zitelli, L. )

    1989-09-01

    Varian is developing high-power, CW gyrotrons at frequencies in the range 100 GHz to 150 GHz, for use in electron cyclotron heating applications. Early test vehicles have utilized a TE{sub 15,2,1} interaction cavity, have achieved short-pulse power levels of 820 kW and average power levels of 80 kW at 140 GHz. Present tests are aimed at reaching 400 kW under CW operating conditions and up to 1 MW for short pulse durations. Work is also underway on modifications to the present design that will enable power levels of up to 1 MW CW to be achieved. 7 refs., 2 figs.

  11. Design considerations for a 100 kW c-w, 140 GHz gyrotron oscillator

    SciTech Connect

    Felch, K.; Bier, R.; Fox, L.; Huey, H.; Ives, L.; Jory, H.; Spang, S.

    1984-01-01

    A gyrotron oscillator capable of generating 100 kW of c-w power is currently under development at Varian. The tube is being designed for operation in the TE/sup 0//sub 031/ cavity mode with the electron beam located at the second radial electric field maximum in the cavity. The electron beam will be produced by a magnetron injection gun and the 56 kG magnetic field required for 140 GHz operation will be provided by a superconducting magnet. Initial design calculations for the important elements of the tube are reported and the various technology issues of the tube design are discussed.

  12. The 28 GHZ, 10 KW, CW Gyrotron Generator for the VENUS ECR Ion Source at LBNL

    NASA Astrophysics Data System (ADS)

    Marks, M.; Evans, S.; Jory, H.; Holstein, D.; Rizzo, R.; Beck, P.; Cisto, B.; Leitner, D.; Lyneis, C. M.; Collins, D.; Dwinell, R. D.

    2005-03-01

    The VIA-301 Heatwave™ gyrotron generator was specifically designed to meet the requirements of the Venus ECR Ion Source at the Lawrence Berkeley National Laboratory (LBNL). VENUS (Versatile ECR ion source for NUclear Science) is a next generation superconducting ECR ion source, designed to produce high current, high charge state ions for the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. VENUS also serves as the prototype ion source for the RIA (Rare Isotope Accelerator) front end [1]. This VIA-301 Heatwave™ gyrotron system provides 100 watts to 10 kW continuous wave (CW) RF output at 28 GHz. The RF output level is smoothly controllable throughout this entire range. The power can be set and maintained to within 10 watts at the higher power end of the power range and to within 30 watts at the lower power end of the power range. A dual directional coupler, analog conditioning circuitry, and a 12-bit analog input to the embedded controller are used to provide a power measurement accurate to within 2%. The embedded controller completes a feedback loop using an external command set point for desired power output. Typical control-loop-time is on the order of 500 mS. Hard-wired interlocks are provided for personnel safety and for protection of the generator system. In addition, there are software controlled interlocks for protection of the generator from high ambient temperature, high water temperature, and other conditions that would affect the performance of the generator or reduce the lifetime of the gyrotron. Cooling of the gyrotron and power supply is achieved using both water and forced circulation of ambient air. Water-cooling provides about 80% of the cooling requirement. Input power to the generator from the prime power line is less than 60 kW at full power. The Heatwave™ may be operated locally via its front panel or remotely via either RS-232 and/or Ethernet connections. Through the RS-232 the forward power, the reflected power, the

  13. The 28 GHZ, 10 KW, CW Gyrotron Generator for the VENUS ECR Ion Source at LBNL

    SciTech Connect

    Marks, M.; Evans, S.; Jory, H.; Holstein, D.; Rizzo, R.; Beck, P.; Cisto, B.; Leitner, D.; Lyneis, C.M.; Collins, D.; Dwinell, R.D.

    2005-03-15

    The VIA-301 Heatwave{sup TM} gyrotron generator was specifically designed to meet the requirements of the Venus ECR Ion Source at the Lawrence Berkeley National Laboratory (LBNL). VENUS (Versatile ECR ion source for NUclear Science) is a next generation superconducting ECR ion source, designed to produce high current, high charge state ions for the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. VENUS also serves as the prototype ion source for the RIA (Rare Isotope Accelerator) front end].This VIA-301 Heatwave{sup TM} gyrotron system provides 100 watts to 10 kW continuous wave (CW) RF output at 28 GHz. The RF output level is smoothly controllable throughout this entire range. The power can be set and maintained to within 10 watts at the higher power end of the power range and to within 30 watts at the lower power end of the power range. A dual directional coupler, analog conditioning circuitry, and a 12-bit analog input to the embedded controller are used to provide a power measurement accurate to within 2%. The embedded controller completes a feedback loop using an external command set point for desired power output. Typical control-loop-time is on the order of 500 mS. Hard-wired interlocks are provided for personnel safety and for protection of the generator system. In addition, there are software controlled interlocks for protection of the generator from high ambient temperature, high water temperature, and other conditions that would affect the performance of the generator or reduce the lifetime of the gyrotron. Cooling of the gyrotron and power supply is achieved using both water and forced circulation of ambient air. Water-cooling provides about 80% of the cooling requirement. Input power to the generator from the prime power line is less than 60 kW at full power. The Heatwave{sup TM} may be operated locally via its front panel or remotely via either RS-232 and/or Ethernet connections. Through the RS-232 the forward power, the reflected power

  14. Detailed Consideration of Experimental Results of Gyrotron FU CW II Developed as a Radiation Source for DNP-NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Agusu, La; Idehara, T.; Ogawa, I.; Saito, T.; Kanemaki, T.; Takahashi, H.; Fujiwara, T.

    2007-07-01

    A CW gyrotron for the sensitivity enhancement of NMR spectroscopy through dynamic nuclear polarization has been designed. The gyrotron operates at the second harmonic and frequency of 394.6 GHz with the main operating mode TE0,6. Operating conditions of other neighboring cavity modes such as TE2,6 at frequency of 392.6 GHz and TE2,3 at frequency of 200.7 GHz were also considered. The experimental conditions of the gyrotron at low and high voltages are simulated. The output power of 56 watts corresponds to the efficiency of 2 percent at low voltage operation and frequency of 394.6 GHz is expected.

  15. Design considerations for a 1 MW CW gyrotron with an internal converter

    SciTech Connect

    Felch, K.; Chu, T.S.; Huey, H.; Jory, H.; Neilson, J.; Schumacher, R.; Lorbeck, J.A.; Vernon, R.J.

    1993-07-01

    Varian is carrying out the development of high-power, CW gyrotrons at frequencies ranging from 100--140 GHz. Recent experiments, carried out at a frequency of 110 GHz, resulted in the generation of output powers of 500 kW for 2.5-second pulses and 1 MW for 1 ms pulse durations. The output mode of this tube was a whispering-gallery mode, based on the TE{sub 22,2} mode employed in the interaction cavity. Current design activity is aimed at producing a 1 MW CW gryotron at the same frequency, but with a guassian output mode structure. This type of output mode is desirable for low-loss transmission in a corrugated waveguide or mirror transmission line. In addition to the change in output coupling, the cavity mode will be changed to the TE{sub 22,6} mode. The higher order cavity mode is consistent with higher power or higher frequency requirements that will be addressed in subsequent development activities.

  16. Series of powerful CW gyrotrons in the range 105 - 140 GHz

    NASA Astrophysics Data System (ADS)

    Denisov, Gregory; Kazansky, Igor; Malygin, Vladimir; Soluyanova, Elena; Tai, Evgeny; Chirkov, Aleksey

    2017-07-01

    GYCOM in collaboration with Institute of Applied Physics (IAP) designed, fabricated and tested two different gyrotrons with similar to ITER parameters at 105 - 140 GHz frequency range. Set of gyrotron system beside the tube includes matching optic unit (MOU) and elements of evacuated transmission lines. One gyrotron system was installed and operates at plasma machines EAST / ASIPP / China, another system is delivered to KSTAR / NFRI / Korea.

  17. Continuously Frequency Tunable High Power Sub-THz Radiation Source—Gyrotron FU CW VI for 600 MHz DNP-NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Idehara, Toshitaka; Kosuga, Kosuke; Agusu, La; Ikeda, Ryosuke; Ogawa, Isamu; Saito, Teruo; Matsuki, Yoh; Ueda, Keisuke; Fujiwara, Toshimichi

    2010-07-01

    A high frequency gyrotron with a 15 T superconducting magnet named Gyrotron FU CW VI has achieved continuous frequency tuning through the relatively wide range of 1.5 GHz near 400 GHz. The operation is at the fundamental cyclotron resonance of the TE06 cavity mode with many higher order axial modes. The output power measured at the end of the circular waveguide system ranges from 10 to 50 watts at the low acceleration voltage of 12 kV for beam electrons. The beam current is also low. It is around 250 mA. This gyrotron is designed as a demountable radiation source for the 600 MHz DNP-NMR spectroscopy. The design and operation results of the gyrotron FU CW VI are presented.

  18. Beam-wave interaction analysis of a 42 GHz, 200 kW CW gyrotron

    SciTech Connect

    Ashutosh; Singh, Rupendra; Jain, P.K. E-mail: rupendrasingh04@gmail.com

    2011-07-01

    In this paper, the self-consistent large-signal formulation is used to study the beam-wave interaction mechanism in a gyrotron oscillator. The nonlinear interaction has been computed by solving the set of self-consistent nonlinear equations along the interaction length using numerical method. Consequently, the computation of energy, phase, output power, and efficiency of a gyrotron is made. The computed results were found to be matching with the published results. A 42 GHz, 200 kW output power gyrotron operating in TE{sub 03} mode is analysed using this analysis and results found meeting desired specifications. (author)

  19. Development of a kW Level-200 GHz Gyrotron FU CW GI with an Internal Quasi-optical Mode Convertor

    NASA Astrophysics Data System (ADS)

    Tatematsu, Yoshinori; Yamaguchi, Yuusuke; Idehara, Toshitaka; Ozeki, Takanori; Ikeda, Ryosuke; Kanemaki, Tomohiro; Ogawa, Isamu; Saito, Teruo

    2012-03-01

    Development of gyrotrons with an internal mode convertor has started in Research Center for Development of Far-Infrared Region, University of Fukui (FIR FU). As the first gyrotron of such a kind, we have designed and manufactured Gyrotron FU CW GI. It operates at 203 GHz at fundamental cyclotron resonance. We have designed a cavity and a mode convertor under some constraints such as reuse of an electron gun and small diameter of a magnet bore. Designed output power is about 1 kW. We have succeeded in observation of a circular radiation pattern. The maximum observed output power is 0.5 kW for the setting cathode voltage of 20 kV and the beam current of 0.5 A. This success makes gyrotron development in FIR FU to proceed to a new stage.

  20. Development program for a 200 kW, cw gyrotron. Final report

    SciTech Connect

    DeHope, W.J.; Ferguson, P.E.; Hart, S.L.; Matranga, V.A.; Sandoval, J.J.; Schmitt, M.J.; Tancredi, J.J.; Wozniak, M.A.

    1984-02-01

    Development of a millimeter-wave device to produce 200 kW of continuous wave power at 60 GHz is described. The device, a gyrotron oscillator, is intended for electron-cyclotron heating of fusion plasmas. The design philosophy is herein discussed and experimental results, both diagnostic and long pulse, are given.

  1. Design and Operating Characteristics of a CW Relevant Quasi-Optical Gyrotron with Variable Mirror Separation

    DTIC Science & Technology

    1989-06-26

    Division 600 Hicks Rd. Rolling Meadows, Illinois 60008 Attn: Dr. Gunter Dohler 1 copy Oak Ridge National Laboratory P.O. Box Y Mail Stop 3 Building 9201 -2...Gyrotron with Variable Mirror Separation 12 . PERSONAL AUTHOR(S) (See page ii) 13a. TYPE OF REPORT 13b TIME COVERED . 4 DATE OF REPORT (Year, Month. Day) ,S...approximately 4 % over the 12 /sec flat top of the cathode voltage pulse. The 10-90% rise time of the cathode pulse was 3.5 psec, and the 90-10% fall time

  2. Development program for a 200 kW, cw gyrotron. Quarterly report No. 11, January-March 1982

    SciTech Connect

    Tancredi, J.J.; Caplan, M.; Sandoval, J.J.; Matranga, V.A.

    1982-01-01

    The objective of this program is the design and development of a millimeter wave device to produce 200 kW of continuous-wave power at 60 GHz. The device, a gyrotron oscillator, will be compatible with power delivery to an electron-cyclotron plasma. Smooth control of RF power output over a 17 dB range is required, and the device should be capable of operation into a severe time-varying load mismatch. During this report period, the beam instability problem which plagued S/N 1 testing was evaluated in more detail. Separate tests were conducted on the gun tester and the lossy drift section, as well as both of these combined, and the results were compared to gyrotron tests on S/N 1. The instability problem now appears to be associated with RF leakage from the cavity.

  3. Further Characterization of 394-GHz Gyrotron FU CW GII with Additional PID Control System for 600-MHz DNP-SSNMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ueda, Keisuke; Matsuki, Yoh; Fujiwara, Toshimichi; Tatematsu, Yoshinori; Ogawa, Isamu; Idehara, Toshitaka

    2016-09-01

    A 394-GHz gyrotron, FU CW GII, has been designed at the University of Fukui, Japan, for dynamic nuclear polarization (DNP)-enhanced solid-state nuclear magnetic resonance (SSNMR) experiments at 600-MHz 1H resonant frequency. After installation at the Institute for Protein Research (IPR), Osaka University, Japan, a PID feedback control system was equipped to regulate the electron gun heater current for stabilization of the electron beam current, which ultimately achieved stabilization of output power when operating in continuous wave (CW) mode. During exploration to further optimize operating conditions, a continuous tuning bandwidth of approximately 1 GHz was observed by varying the operating voltage at a fixed magnetic field. In the frequency range required for positive DNP enhancement, the output power was improved by increasing the magnetic field and the operating voltage from their initial operational settings. In addition, fine tuning of output frequency by varying the cavity cooling water temperature was demonstrated. These operating conditions and ancillary enhancements are expected to contribute to further enhancement of SSNMR signal.

  4. Development program for a 200 kW, CW gyrotron. Quarterly report No. 16, April-June 1983

    SciTech Connect

    DeHope, W.J.; Ferguson, P.E.; Hart, S.L.; Matranga, V.A.; Sandoval, J.J.; Schmitt, M.J.; Tancredi, J.J.

    1983-01-01

    The objective of this program is the design and development of a millimeter-wave device to produce 200 kW of continuous wave power at 60 GHz. The device, a gyrotron oscillator, will be compatible with power delivery to an electron-cyclotron heated plasma. Smooth control of rf power over a 17 dB range is required, and the device should be capable of operation into a severely time-varying load mismatch. Progress is presented in the testing, analyses and understanding of S/N 1B behavior and in preparing S/N 3 for test in the coming report period.

  5. Rapid Sintering of Silica Xerogel Ceramic Derived from Sago Waste Ash Using Sub-millimeter Wave Heating with a 300 GHz CW Gyrotron

    NASA Astrophysics Data System (ADS)

    Aripin, Haji; Mitsudo, Seitaro; Sudiana, I. Nyoman; Tani, Shinji; Sako, Katsuhide; Fujii, Yutaka; Saito, Teruo; Idehara, Toshitaka; Sabchevski, Sliven

    2011-06-01

    In this paper, we present and discuss experimental results from a microwave sintering of a silica-glass ceramic, produced from a silica xerogel extracted from a sago waste ash. As a radiation source for the microwave heating a sub-millimeter wave gyrotron (Gyrotron FU CW I) with an output frequency of 300 GHz has been used. The powders of silica xerogel have been dry pressed and then sintered at temperatures ranging from 300°C to 1500°C. The influence of the sintering temperature on the technological properties such as porosity and bulk density was studied in detail. Furthermore, X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy have been used in order to study the structure of the produced silica glass-ceramics. It has been found that the silica xerogel crystallizes at a temperature of 800°C, which is about 200°C lower than the one observed in the conventional process. The silica xerogel samples sintered by their irradiation with a sub-millimeter wave at 900°C for 18 minutes are fully crystallized into a silica glass-ceramic with a density of about 2.2 g/cm3 and cristobalite as a major crystalline phase. The results obtained in this study allow one to conclude that the microwave sintering with sub-millimeter waves is an appropriate technological process for production of silica glass-ceramics from a silica xerogel and is characterized with such advantages as shorter times of the thermal cycle, lower sintering temperatures and higher quality of the final product.

  6. Development program for a 200-kW, c-w gyrotron. Quarterly report No. 7, January-March 1981

    SciTech Connect

    Tancredi, J J; Caplan, M; Sandoval, J J; Jordan, E; Matranga, V A

    1981-01-01

    The objective of this program is the design and development of a millimeter-wave device to produce 200 kW of continuous-wave power at 60 GHz. The device, which will be a gyrotron oscillator, will be compatible with power delivery to an electron-cyclotron plasma. Smooth control of rf power output over a 17 dB range is required, and the device should be capable of operation into a severe time-varying rf load mismatch. An interim program goal is to demonstrate operation at 100 ms pulse widths by 31 December 1981. During this quarter, progress was made in the areas of tube, solenoid, and facility construction. Two magnetron injection gun assemblies were completed, and one was partially evaluated as a gun tester. The superconducting solenoid was assembled, but a vacuum leak prevented early delivery in March. Construction began on the gyrotron test facility by enclosing the area and providing bake-out and vacuum processing utilities.

  7. Development program for a 200 kW, c-w gyrotron. Quarterly report No. 8, April-June 1981

    SciTech Connect

    Tancredi, J J; Caplan, M; Sandoval, J J; Jordan, E N; Matranga, V A

    1981-01-01

    The objective of this program is the design and development of a millimeter wave device to produce 200 kW of continuous-wave power at 60 GHz. The device, a gyrotron oscillator, will be compatible with power delivery to an electron-cyclotron plasma. Smooth control of RF power output over a 17 dB range is required, and the device should be capable of operation into a severe time-varying load mismatch. The first tube was assembled and vacuum processed during this quarter. However RF evaluation was postponed because of a superconducting solenoid malfunction. The emission quality of a gun tester was confirmed. The gun tester was then used to check out a cathode modulated pulser and resistor grid divider. The first phase of the Gyrotron Test Facility was completed when the vacuum processing equipment and short pulse modulator were brought on-line. The second Facility phase was started with the reassembly of the medium pulse (100 ms) modulator.

  8. Development program for a 200 kW, CW gyrotron. Quarterly report No. 3, January-March 1980

    SciTech Connect

    Arnold, K.W.; Tancredi, J.J.; Caplan, M.; Ha, K.W.; Birnbaum, D.N.; Weiss, W.

    1980-01-01

    The objective of this program is the design and development of a millimeter-wave device to produce 200 kW of continuous-wave power at 60 GHz. The device, which will be a gyrotron oscillator, will be compatible with power delivery to an electron-cyclotron plasma. Smooth control of rf power output over a 17 dB range is required, and the device should be capable of operation into a severe time-varying rf load mismatch. The duration of the program is 36 months, to encompass the building and test up to twelve devices. The magnetron injection gun is well understood and allows the user of the extraction anode (as well as cathode temperature variation) to vary the rf power out. At least two design approaches will be taken with respect to the collector, which has to be able to dissipate over 560 kW in underpressed operation. Fabrication and processing of prototype devices will proceed in parallel.

  9. Functional and shunt states of bacteriorhodopsin resolved by 250 GHz dynamic nuclear polarization–enhanced solid-state NMR

    PubMed Central

    Bajaj, Vikram S.; Mak-Jurkauskas, Melody L.; Belenky, Marina; Herzfeld, Judith; Griffin, Robert G.

    2009-01-01

    Observation and structural studies of reaction intermediates of proteins are challenging because of the mixtures of states usually present at low concentrations. Here, we use a 250 GHz gyrotron (cyclotron resonance maser) and cryogenic temperatures to perform high-frequency dynamic nuclear polarization (DNP) NMR experiments that enhance sensitivity in magic-angle spinning NMR spectra of cryo-trapped photocycle intermediates of bacteriorhodopsin (bR) by a factor of ≈90. Multidimensional spectroscopy of U-13C,15N-labeled samples resolved coexisting states and allowed chemical shift assignments in the retinylidene chromophore for several intermediates not observed previously. The correlation spectra reveal unexpected heterogeneity in dark-adapted bR, distortion in the K state, and, most importantly, 4 discrete L substates. Thermal relaxation of the mixture of L's showed that 3 of these substates revert to bR568 and that only the 1 substate with both the strongest counterion and a fully relaxed 13-cis bond is functional. These definitive observations of functional and shunt states in the bR photocycle provide a preview of the mechanistic insights that will be accessible in membrane proteins via sensitivity-enhanced DNP NMR. These observations would have not been possible absent the signal enhancement available from DNP. PMID:19474298

  10. Functional and shunt states of bacteriorhodopsin resolved by 250 GHz dynamic nuclear polarization-enhanced solid-state NMR.

    PubMed

    Bajaj, Vikram S; Mak-Jurkauskas, Melody L; Belenky, Marina; Herzfeld, Judith; Griffin, Robert G

    2009-06-09

    Observation and structural studies of reaction intermediates of proteins are challenging because of the mixtures of states usually present at low concentrations. Here, we use a 250 GHz gyrotron (cyclotron resonance maser) and cryogenic temperatures to perform high-frequency dynamic nuclear polarization (DNP) NMR experiments that enhance sensitivity in magic-angle spinning NMR spectra of cryo-trapped photocycle intermediates of bacteriorhodopsin (bR) by a factor of approximately 90. Multidimensional spectroscopy of U-(13)C,(15)N-labeled samples resolved coexisting states and allowed chemical shift assignments in the retinylidene chromophore for several intermediates not observed previously. The correlation spectra reveal unexpected heterogeneity in dark-adapted bR, distortion in the K state, and, most importantly, 4 discrete L substates. Thermal relaxation of the mixture of L's showed that 3 of these substates revert to bR(568) and that only the 1 substate with both the strongest counterion and a fully relaxed 13-cis bond is functional. These definitive observations of functional and shunt states in the bR photocycle provide a preview of the mechanistic insights that will be accessible in membrane proteins via sensitivity-enhanced DNP NMR. These observations would have not been possible absent the signal enhancement available from DNP.

  11. Status of gyrotron developments at Varian Associates

    SciTech Connect

    Jory, H.

    1984-01-01

    The status of gyrotrons developed by Varian for fusion heating applications will be briefly reviewed. Development work started in 1976 with the goal of 200 kW CW at 28 GHz. A more recent program was to develop 200 kW CW at 60 GHz. Pulsed and CW tubes produced by these programs will be briefly described and the scaling of these designs to other frequencies including 53, 56 and 70 GHz will be discussed. A 35 GHz design will also be described. Future efforts for gyrotrons at 120 and 140 GHz will also be discussed.

  12. A 250-GHz CARM (Cyclotron Auto Resonance Maser) oscillator experiment driven by an induction linac

    SciTech Connect

    Caplan, M.; Kulke, B.; Bubp, D.G. ); McDermott, D.; Luhmann, N. )

    1990-09-14

    A 250-GHz Cyclotron Auto Resonance Maser (CARM) oscillator has been designed and constructed and will be tested using a 1-kA, 2-MeV electron beam produced by the induction linac at the Accelerator Research Center (ARC) facility of Lawrence Livermore National Laboratory (LLNL). The oscillator circuit was made to operate in the TE{sub 11} mode at ten times cutoff using waveguide Bragg reflectors to create an external cavity Q of 8000. Theory predicts cavity fill times of less than 30 ns (pulse length) and efficiencies approaching 20% is sufficiently low transverse electron velocity spreads are maintained (2%).

  13. Pierce-Wiggler electron beam system for 250 GHz GYRO-BWO: Final report

    SciTech Connect

    Pirkle, D.R.; Alford, C.W.; Anderson, M.H.; Garcia, R.F.; Legarra, J.R.; Nordquist, A.L.

    1989-01-01

    This final report summarizes the design and performance of the VUW-8028 Pierce-Wiggler electron beam systems, which can be used to power high frequency gyro-BWO's. The operator's manual for this gyro-BWO beamstick is included as appendix A. Researchers at Lawrence Livermore National Laboratory (LLNL) are developing a gyro-BWO with a center frequency of 250 GHz, 6% bandwidth, and 10 kV peak output power. The gyro-BWO will be used to drive a free electron laser amplifier at LLNL. The electron beam requirements of the gyro-BWO application are: Small beam size, .100 inch at 2500 gauss axial magnetic field; a large fraction of the electron energy in rotational velocity; ability to vary the electrons' axial velocity easily, for electronic tuning; and low velocity spread i.e. little variation in the axial velocities of the electrons in the interaction region. 1 ref., 13 figs.

  14. A 250 GHz microwave interferometer for divertor experiments on DIII-D

    SciTech Connect

    James, R.A.; Nilson, D.G.; Stever, R.D.; Hill, D.N.; Casper, T.A.

    1994-01-31

    A new 250 GHz, two-frequency microwave interferometer system has been developed to diagnose divertor plasmas on DIII-D. This diagnostic will measure the line-averaged density across both the inner and outer, lower divertor legs. With a cut-off density of over 7 {times} 10{sup 14} cm{sup {minus}3}, temporal measurements of ELMs, MARFs and plasma detachment are expected. The outer leg system will use a double pass method while the inner leg system will be single pass. Two special 3D carbon composite tiles are used, one to protect the microwave antennas mounted directly under the strike point and the other as the outer leg reflecting surface. Performance, design constraints, and the thermalmechanical design of the 3D carbon composite tiles are discussed.

  15. Innovation on high-power long-pulse gyrotrons

    NASA Astrophysics Data System (ADS)

    Litvak, Alexander; Sakamoto, Keishi; Thumm, Manfred

    2011-12-01

    Progress in the worldwide development of high-power gyrotrons for magnetic confinement fusion plasma applications is described. After technology breakthroughs in research on gyrotron components in the 1990s, significant progress has been achieved in the last decade, in particular, in the field of long-pulse and continuous wave (CW) gyrotrons for a wide range of frequencies. At present, the development of 1 MW-class CW gyrotrons has been very successful; these are applicable for self-ignition experiments on fusion plasmas and their confinement in the tokamak ITER, for long-pulse confinement experiments in the stellarator Wendelstein 7-X (W7-X) and for EC H&CD in the future tokamak JT-60SA. For this progress in the field of high-power long-pulse gyrotrons, innovations such as the realization of high-efficiency stable oscillation in very high order cavity modes, the use of single-stage depressed collectors for energy recovery, highly efficient internal quasi-optical mode converters and synthetic diamond windows have essentially contributed. The total tube efficiencies are around 50% and the purity of the fundamental Gaussian output mode is 97% and higher. In addition, activities for advanced gyrotrons, e.g. a 2 MW gyrotron using a coaxial cavity, multi-frequency 1 MW gyrotrons and power modulation technology, have made progress.

  16. Recent result of gyrotron operation in NIFS

    NASA Astrophysics Data System (ADS)

    Ito, Satoshi; Shimozuma, Takashi; Yoshimura, Yasuo; Igami, Hiroe; Takahashi, Hiromi; Nishiura, Masaki; Kobayashi, Sakuji; Mizuno, Yoshinori; Okada, Kota; Kubo, Shin

    2015-03-01

    In the last Large Helical Device (LHD) experimental campaign, a 154GHz gyrotron which had been conditioned to generate 1 MW/2 s, 0.5 MW/CW was installed for LHD experiments. Four high power gyrotrons (three-77 GHz/1~1.5 MW and one-154 GHz/1 MW) and a CW gyrotron (84 GHz/0.2 MW) are ready. Our experiment requires high energy and various injection patterns for Electron Cyclotron Resonance Heating (ECRH). Higher individual injection power and various injection patterns, we developed a power enhancement method by stepped anode acceleration voltage control and operated the gyrotron in the hard excitation region. These operations were realized by a remote controlled waveform generator. However the oscillation map of high power or long pulse operation in the hard excitation region were limited because in order to achieve the hard excitation region by the anode voltage control one must pass through the high anode current phase within a time short enough that the anode or the anode power supply is not overloaded. This limitation becomes more critical when the gyrotron beam current is increased in order to increase the output power. In the long pulse operation it was impossible to reach the hard excitation region in a low beam current (<10A).

  17. Soviet Development of Gyrotrons

    DTIC Science & Technology

    1986-05-01

    order to increase gyrotron power , Strelkov noted that "At the present time, highly efficient gyrotrons with weakly relativistic beams have been built...Consequently, the power of vacuum gyrotrons is limited: for examl)le, for a I MeV beam, the max- imum theoretical power of a high- efficiency 3)) percent...45’ and 0.5 kA, producing an output power of 25 MW. Further increase in injection current in the vacuum gyrotron decreased efficiency without

  18. Development of gyrotrons for fusion with power exceeding 1 MW over a wide frequency range

    NASA Astrophysics Data System (ADS)

    Kariya, T.; Imai, T.; Minami, R.; Numakura, T.; Eguchi, T.; Kato, T.; Endo, Y.; Ichimura, M.; Shimozuma, T.; Kubo, S.; Takahashi, H.; Yoshimura, Y.; Igami, H.; Ito, S.; Mutoh, T.; Sakamoto, K.; Idei, H.; Zushi, H.; Nagasaki, K.; Sano, F.; Ono, M.; Mitsunaka, Y.

    2015-09-01

    Megawatt-class gyrotrons covering a wide frequency range (14 GHz-300 GHz) are in increasing demand for nuclear fusion. Recent electron cyclotron heating and electron cyclotron current drive experiments highlight a requirement of megawatt-scale gyrotrons at a relatively lower frequency (14-35 GHz) range of some plasma devices, like GAMMA 10/PDX of the University of Tsukuba, QUEST of Kyushu University, NSTX-U of Princeton Plasma Physics Laboratory, and Heliotron J of Kyoto University. Collaborative studies for designing a new 28 GHz/35 GHz dual-frequency gyrotron and a 14 GHz gyrotron have commenced. Operation above 1 MW of 28 GHz/35 GHz dual oscillation was demonstrated experimentally. Further in the design of dual-frequency gyrotron, operations with 2 MW 3 s and 0.4 MW CW (continuous wave) at 28 GHz, and power exceeding 1 MW for 3 s at 34.8 GHz have been shown to be feasible. The 14 GHz gyrotron is expected to operate above 1 MW. We are also developing higher frequency gyrotrons (77-300 GHz). The joint program of National Institute for Fusion Science and the University of Tsukuba developed two new 154 GHz gyrotrons for the large helical device after the demonstration of three 77 GHz gyrotrons. The 154 GHz gyrotrons achieved a maximum output power of 1.25 MW and quasi-CW operation of 0.35 MW for 30 min.

  19. The Development of 460 GHz gyrotrons for 700 MHz DNP-NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Idehara, T.; Tatematsu, Y.; Yamaguchi, Y.; Khutoryan, E. M.; Kuleshov, A. N.; Ueda, K.; Matsuki, Y.; Fujiwara, T.

    2015-07-01

    Two demountable gyrotrons with internal mode converters were developded as sub-THz radiation sources for 700 MHz DNP (Dynamic Nuclear Polarization) enhanced NMR spectroscopy. Experimental study on the DNP-NMR spectroscopy will be carried out in Osaka University, Institute for Protein Research, as a collaboration with FIR UF. Both gyrotrons operate near 460 GHz and the output CW power measured at the end of transmission system made by circular waveguides is typically 20 to 30 watts. One of them named Gyrotron FU CW GVI (we are using "Gyrotron FU CW GO-1" as an official name in Osaka University) is designed to have a special function of high speed frequency modulation δ f within 100 MHz band. This will expand excitable band width of ESR and increase the number of electron spins contributing to DNP. The other gyrotron, Gyrotron FU CW GVIA ("Gyrotron FU CW GO-II") has a function of frequency tunability Δ f in the range of wider than 1.5 GHz, which is achieved in steady state by changing magnetic field intensity. This function should be used for adjusting the output frequency at the optimal value to achieve the highest enhancement factor of DNP.

  20. Terahertz Gyrotrons at IAP RAS: Status and New Designs

    NASA Astrophysics Data System (ADS)

    Bratman, V. L.; Glyavin, M. Yu.; Kalynov, Yu. K.; Litvak, A. G.; Luchinin, A. G.; Savilov, A. V.; Zapevalov, V. E.

    2011-03-01

    Powerful gyrotrons with radiation frequencies in the range 0.33-0.65 THz were demonstrated at the IAP as early as in the 1970-1980s. This trend has recently been renewed in connection with a significant increase in interest in terahertz frequency range. In the course of new experiments, the radiation frequency of pulsed gyrotrons was increased up to 1.3 THz and 1 THz at the fundamental and third cyclotron harmonics, respectively. In addition, gyrotrons operated in CW regime with a frequency of 0.3 THz for technological applications (in collaboration with the University of Fukui, Japan) and 0.26 THz for the dynamic nuclear polarization at a high-field NMR were implemented. Designs of a pulsed fundamental-harmonic gyrotron with MW-level power at 0.3 THz and a CW kW-level third-harmonic gyrotron with a frequency of 0.4 THz are currently developed. Estimates show that modern techniques for the creation of strong magnetic fields now make it possible to realize gyrotrons with an operating frequency at least up to 1-1.5 THz. Such generators utilize a relatively low particle energy and can provide higher average power than the existing FELs.

  1. Stabilization of Gyrotron Frequency by PID Feedback Control on the Acceleration Voltage

    NASA Astrophysics Data System (ADS)

    Khutoryan, E. M.; Idehara, T.; Kuleshov, A. N.; Tatematsu, Y.; Yamaguchi, Y.; Matsuki, Y.; Fujiwara, T.

    2015-12-01

    The results of frequency stabilization by proportional-integral-derivative (PID) feedback control of acceleration voltage in the 460-GHz Gyrotron FU CW GVI (the official name in Osaka University is Gyrotron FU CW GOI) are presented. The experiment was organized on the basis of the frequency modulation by modulation of acceleration voltage of beam electrons. The frequency stabilization during 10 h experiment was better than 10-6, which is compared with the results of the frequency deviation in free-running gyrotron operation.

  2. Megawatt Long-Pulse Gyrotrons for ECH and ECCD Applications

    NASA Astrophysics Data System (ADS)

    Cauffman, S.; Felch, K.; Blank, M.; Borchard, P.; Cahalan, P.; Chu, T. S.; Jory, H.; Saraph, G.; Wagner, D.

    2000-10-01

    High-power long-pulse mm-wave sources are required for electron cyclotron heating and current drive in large-scale fusion experiments. Gyrotron oscillator technology has developed considerably in recent years, enabling the generation of Gaussian mm-wave beams at megawatt power levels for pulse durations in excess of 10 seconds from a single unit. This presentation summarizes CPI's recent gyrotron development activities for fusion applications. CPI has fabricated a series of 110 GHz gyrotrons for use in DIII-D ECH experiments. The three most recent gyrotrons in this series employ a diode electron gun, an internal quasi-optical mode converter, and a CVD diamond output window. Further development activities funded by DOE are aimed at incorporating a multi-stage depressed electron beam collector to improve efficiency and optimizing other design components to enable output power levels of 1.5 MW. CPI is also constructing a prototype 140 GHz 1 MW CW gyrotron for use with the W7-X stellarator. This gyrotron employs a single-stage depressed collector and a high-voltage design eliminating the need for oil around the insulating ceramics. A similar configuration was employed successfully in a recently delivered 70 GHz 500 kW gyrotron, and is being used for an 84 GHz 500 kW system under development for the KSTAR tokamak program. Design features of these devices will be compared, and empirical results will be presented for those devices for which test data is available.

  3. Photonic-band-gap traveling-wave gyrotron amplifier.

    PubMed

    Nanni, E A; Lewis, S M; Shapiro, M A; Griffin, R G; Temkin, R J

    2013-12-06

    We report the experimental demonstration of a gyrotron traveling-wave-tube amplifier at 250 GHz that uses a photonic band gap (PBG) interaction circuit. The gyrotron amplifier achieved a peak small signal gain of 38 dB and 45 W output power at 247.7 GHz with an instantaneous -3  dB bandwidth of 0.4 GHz. The amplifier can be tuned for operation from 245-256 GHz. The widest instantaneous -3  dB bandwidth of 4.5 GHz centered at 253.25 GHz was observed with a gain of 24 dB. The PBG circuit provides stability from oscillations by supporting the propagation of transverse electric (TE) modes in a narrow range of frequencies, allowing for the confinement of the operating TE03-like mode while rejecting the excitation of oscillations at nearby frequencies. This experiment achieved the highest frequency of operation for a gyrotron amplifier; at present, there are no other amplifiers in this frequency range that are capable of producing either high gain or high output power. This result represents the highest gain observed above 94 GHz and the highest output power achieved above 140 GHz by any conventional-voltage vacuum electron device based amplifier.

  4. Photonic-Band-Gap Traveling-Wave Gyrotron Amplifier

    PubMed Central

    Nanni, E. A.; Lewis, S. M.; Shapiro, M. A.; Griffin, R. G.; Temkin, R. J.

    2014-01-01

    We report the experimental demonstration of a gyrotron traveling-wave-tube amplifier at 250 GHz that uses a photonic band gap (PBG) interaction circuit. The gyrotron amplifier achieved a peak small signal gain of 38 dB and 45 W output power at 247.7 GHz with an instantaneous −3 dB bandwidth of 0.4 GHz. The amplifier can be tuned for operation from 245–256 GHz. The widest instantaneous −3 dB bandwidth of 4.5 GHz centered at 253.25 GHz was observed with a gain of 24 dB. The PBG circuit provides stability from oscillations by supporting the propagation of transverse electric (TE) modes in a narrow range of frequencies, allowing for the confinement of the operating TE03-like mode while rejecting the excitation of oscillations at nearby frequencies. This experiment achieved the highest frequency of operation for a gyrotron amplifier; at present, there are no other amplifiers in this frequency range that are capable of producing either high gain or high output power. This result represents the highest gain observed above 94 GHz and the highest output power achieved above 140 GHz by any conventional-voltage vacuum electron device based amplifier. PMID:24476286

  5. Megawatt, 330 Hz PRF tunable gyrotron experiments

    NASA Astrophysics Data System (ADS)

    Spark, S. N.; Cross, A. W.; Phelps, A. D. R.; Ronald, K.

    1994-12-01

    Repetitively pulsed and cw gyrotrons have hitherto used thermionic cathodes, whereas cold cathode gyrotrons have normally operated as ‘single shot’ devices. The novel results presented here show that cold cathode gyrotrons can be successfully pulsed repetitively. A tunable gyrotron with a pulse repetition frequency (PRF) of 150Hz is demonstrated. This system developed >4MW mm-wave output pulses at 100GHz. The gyrotron is based on a two-electrode configuration comprising a field-immersed, field emission, cold cathode and a shaped anode cavity. A superconducting magnet was used to produce the homogeneous intra-cavity magnetic field and a cable pulser was used to drive the electron beam. This pulser produced up to a (200±20)kV pulse with 10ns rise time, a 100ns flat top, a 10ns decay with a characteristic impedance of 200Ω. The energy storage capacity of the cable pulser was 35J. The charging unit limited the maximum PRF to 330Hz. Due to spark gap switching limitations 330Hz was only obtainable in 5 to 10 pulse bursts. For substantial periods of the order of 30 seconds, 100Hz PRF was achieved over an oscillating range of 28 to 100GHz and 150Hz PRF was achieved at 80GHz. No degradation effects on the mm-wave output pulse was evident due to diode recovery time throughout this series of results. A subsequent conclusion is that the diode recovery time in our cold cathode gyrotron is less than 3ms.

  6. Low-voltage gyrotrons

    NASA Astrophysics Data System (ADS)

    Glyavin, M. Yu.; Zavolskiy, N. A.; Sedov, A. S.; Nusinovich, G. S.

    2013-03-01

    For a long time, the gyrotrons were primarily developed for electron cyclotron heating and current drive of plasmas in controlled fusion reactors where a multi-megawatt, quasi-continuous millimeter-wave power is required. In addition to this important application, there are other applications (and their number increases with time) which do not require a very high power level, but such issues as the ability to operate at low voltages and have compact devices are very important. For example, gyrotrons are of interest for a dynamic nuclear polarization, which improves the sensitivity of the nuclear magnetic resonance spectroscopy. In this paper, some issues important for operation of gyrotrons driven by low-voltage electron beams are analyzed. An emphasis is made on the efficiency of low-voltage gyrotron operation at the fundamental and higher cyclotron harmonics. These efficiencies calculated with the account for ohmic losses were, first, determined in the framework of the generalized gyrotron theory based on the cold-cavity approximation. Then, more accurate, self-consistent calculations for the fundamental and second harmonic low-voltage sub-THz gyrotron designs were carried out. Results of these calculations are presented and discussed. It is shown that operation of the fundamental and second harmonic gyrotrons with noticeable efficiencies is possible even at voltages as low as 5-10 kV. Even the third harmonic gyrotrons can operate at voltages about 15 kV, albeit with rather low efficiency (1%-2% in the submillimeter wavelength region).

  7. Millimeter-wave, megawatt gyrotron development for ECR (electron cyclotron resonance) heating applications

    SciTech Connect

    Jory, H.; Felch, K.; Hess, C.; Huey, H.; Jongewaard, E.; Neilson, J.; Pendleton, R.; Tsirulnikov, M. )

    1990-09-17

    To address the electron cyclotron heating requirements of planned fusion experiments such as the International Thermonuclear Experimental Reactor (ITER) and the Compact Ignition Tokamak (CIT), Varian is developing gyrotrons at frequencies ranging from 100--300 GHz with output power capabilities up to 1 MW CW. Experimental gyrotrons have been built at frequencies between 100--140 GHz, and a study program has addressed the critical elements of designing 280--300 GHz gyrotrons capable of generating CW power levels up to 1 MW. Initial test vehicles at 140 GHz have utilized TE{sub 15,2,1} interaction cavities, and have been designed to generate short-pulse (up to 20 ms) power levels of 1 MW and up to 400 kW CW. Recently, short-pulse power levels of 1040 kW at 38% efficiency have been obtained and average powers of 200 kW have been achieved. Long-pulse operation has been extended to pulse durations of 0.5 seconds at power levels of 400 kW. Gyrotron oscillators capable of generating output powers of 500 kW CW at a frequency of 110 GHz have recently been designed and a prototype is currently being tested. Design work for a 1 MW CW gyrotron at 110 GHz, is in progress. The 1 MW CW tube will employ an output coupling approach where the microwave output is separated from the microwave output. 15 refs., 10 figs., 3 tabs.

  8. Integrated 1.55 µm photomixer local oscillator sources for heterodyne receivers from 70 GHz to beyond 250 GHz

    NASA Astrophysics Data System (ADS)

    Huggard, Peter G.; Azcona, Luis; Laisné, Alexandre; Ellison, Brian N.; Shen, Pengbo; Gomes, Nathan J.; Davies, Phil A.

    2004-10-01

    Photomixing is a flexible and efficient method of providing both local oscillator signals for heterodyne receivers and high frequency phase reference signals. Ultrafast, 70 GHz bandwidth, λ = 1.55 µm, photodiodes from u2t Photonics AG have been incorporated into three designs of mm-wave waveguide mounts. The photomixers utilise a thin freestanding gold foil, or a gold on dielectric, probe to couple power into the waveguide and to deliver the photodiode bias. The frequency coverage of the designs is from 70 GHz to 300 GHz. A method of rapidly characterizing the frequency response of these photomixers using spontaneous-spontaneous beating of light from an EDFA is described. Recent work has been directed at increasing the degree of integration of the photodiode with the waveguide probe and choke filter to reduce the frequency dependence of the output power. A simplified photomixer block manufacturing process has also been introduced. A combined probe and filter structure, impedance matched to both the coplanar output line on the photodiode chip and to 0.4 height milled waveguide, is presented. This matching is achieved over the W-band with a fixed waveguide backshort. We present modelled and experimental results showing the increased efficiency and smoother tuning. The design and frequency response of such a probe is reported. We also present the performance of a simpler mount, operating in the frequency range from 160 GHz to 300 GHz, which generates powers of around 10 µW up to 250 GHz.

  9. Recent Tests on 500 kW and 1 MW, Multi-Second-Pulsed Gyrotrons

    NASA Astrophysics Data System (ADS)

    Felch, K.; Blank, M.; Borchard, P.; Cahalan, P.; Cauffman, S.; Chu, T. S.; Jory, H.

    2003-02-01

    Long-pulse and CW gyrotrons are being developed at CPI for several electron cyclotron heating experiments. Designs at three different frequencies, 110 GHz, 140 GHz and 84 GHz, have recently been tested. Common features of the three designs include single-anode, magnetron-injection electron guns, internal converters that produce a TEM00 Gaussian output mode and CVD (chemical-vapor deposition) diamond output windows. The three designs use different cavity interaction modes and two of the designs employ collector depression to raise the overall efficiency of the gyrotron installations. Further details of the individual designs and the results of tests on the various gyrotrons are discussed below.

  10. Progress on Gyrotrons for ITER and Future Fusion Reactors

    SciTech Connect

    Thumm, Manfred K.

    2009-11-26

    The prototype of the Japan 170 GHz ITER gyrotron holds the energy and efficiency world record of 2.88 GJ (0.8 MW, 3600 s, 57%) with 55% efficiency at 1 MW, 800 s, whereas the Russian 170 GHz ITER prototype tube achieved 0.83 MW with a pulse duration of 203 s at 48% efficiency and 1 MW at 116 s and 52%. The record parameters of the European megawatt-class 140 GHz gyrotron for the Stellarator Wendelstein W7-X are: 0.92 MW output power at 1800 s pulse duration, almost 45% efficiency and 97.5% Gaussian mode purity. All these gyrotrons employ a cylindrical cavity, a quasi-optical output coupler, a synthetic diamond window and a single-stage depressed collector (SDC) for energy recovery. In coaxial cavities the existence of the longitudinally corrugated inner conductor reduces the problems of mode competition and limiting current, thus allowing one to use even higher order modes with lower Ohmic attenuation than in cylindrical cavities. Synthetic diamond windows with a transmission capability of 2 MW, continuous wave (CW) are feasible. In order to keep the number of the required gyrotrons and magnets as low as possible, to reduce the costs of the ITER 26 MW, 170 GHz ECRH system and to allow compact upper launchers for plasma stabilization, 2 MW mm-wave power per gyrotron tube is desirable. The FZK pre-prototype tube for an EU 170 GHz, 2 MW ITER gyrotron has achieved 1.8 MW at 28% efficiency (without depressed collector). Design studies for a 4 MW 170 GHz coaxial-cavity gyrotron with two synthetic diamond output windows and two 2 MW mm-wave output beams for future fusion reactors are currently being performed at FZK. The availability of sources with fast frequency tunability (several GHz s{sup -1}, tuning in 1.5-2.5% steps for about ten different frequencies) would permit the use of a simple, fixed, non-steerable mirror antenna for local current drive (ECCD) experiments and plasma stabilization. GYCOM in Russia develops in collaboration with IPP Garching and FZK an

  11. Experimental tests of a 263 GHz gyrotron for spectroscopic applications and diagnostics of various media

    SciTech Connect

    Glyavin, M. Yu. Denisov, G. G.; Zapevalov, V. E.; Chirkov, A. V.; Fokin, A. P.; Kholoptsev, V. V.; Kuftin, A. N.; Luchinin, A. G.; Golubyatnikov, G. Yu.; Malygin, V. I.; Morozkin, M. V.; Manuilov, V. N.; Proyavin, M. D.; Sedov, A. S.; Tsvetkov, A. I.; Sokolov, E. V.; Tai, E. M.

    2015-05-15

    A 263 GHz continuous-wave (CW) gyrotron was developed at the IAP RAS for future applications as a microwave power source in Dynamic Nuclear Polarization / Nuclear magnetic resonance (DNP/NMR) spectrometers. A new experimental facility with a computerized control was built to test this and subsequent gyrotrons. We obtained the maximum CW power up to 1 kW in the 15 kV/0.4 A operation regime. The power about 10 W, which is sufficient for many spectroscopic applications, was realized in the low current 14 kV/0.02 A regime. The possibility of frequency tuning by variation of the coolant temperature about 4 MHz/1 °C was demonstrated. The spectral width of the gyrotron radiation was about 10{sup −6}.

  12. Experimental tests of a 263 GHz gyrotron for spectroscopic applications and diagnostics of various media.

    PubMed

    Glyavin, M Yu; Chirkov, A V; Denisov, G G; Fokin, A P; Kholoptsev, V V; Kuftin, A N; Luchinin, A G; Golubyatnikov, G Yu; Malygin, V I; Morozkin, M V; Manuilov, V N; Proyavin, M D; Sedov, A S; Sokolov, E V; Tai, E M; Tsvetkov, A I; Zapevalov, V E

    2015-05-01

    A 263 GHz continuous-wave (CW) gyrotron was developed at the IAP RAS for future applications as a microwave power source in Dynamic Nuclear Polarization / Nuclear magnetic resonance (DNP/NMR) spectrometers. A new experimental facility with a computerized control was built to test this and subsequent gyrotrons. We obtained the maximum CW power up to 1 kW in the 15 kV/0.4 A operation regime. The power about 10 W, which is sufficient for many spectroscopic applications, was realized in the low current 14 kV/0.02 A regime. The possibility of frequency tuning by variation of the coolant temperature about 4 MHz/1 °C was demonstrated. The spectral width of the gyrotron radiation was about 10(-6).

  13. Initial Testing of a 140 GHz 1 MW Gyrotron

    NASA Astrophysics Data System (ADS)

    Cauffman, Stephen; Felch, Kevin; Blank, Monica; Borchard, Philipp; Cahalan, Pat; Chu, Sam; Jory, Howard

    2001-10-01

    CPI has completed the fabrication of a 140 GHz 1 MW CW gyrotron to be used on the W7-X stellarator at IPP Greifswald. Testing of the initial build of this gyrotron had just begun when this abstract was prepared, and was expected to finish in September, at which time a planned rebuild of the device was scheduled to begin. This poster will summarize the gyrotron design, present results of initial testing, and outline any design changes planned as a consequence of these results. This gyrotron's design employs a number of advanced features, including a diode electron gun for simplified operation, a single-stage depressed collector to enhance overall efficiency, a CVD diamond output window, an internal mode converter that converts the excited TE28,7 cavity mode to a Gaussian output beam, and a high-voltage layout that locates all external high voltage below the superconducting magnet system without requiring an oil tank for insulation. Similar features are being used for an 84 GHz 500 kW system being built for the KSTAR tokamak program and for a 110 GHz 1.5 MW system being designed in collaboration with MIT, UMd, UW, GA, and Calabazas Creek Research with funding provided by DOE.

  14. Operation of a step tunable megawatt gyrotron

    NASA Technical Reports Server (NTRS)

    Kreischer, K. E.; Temkin, R. J.

    1989-01-01

    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.

  15. Simultaneous Stabilization of Gyrotron Frequency and Power by PID Double Feedback Control on the Acceleration and Anode Voltages

    NASA Astrophysics Data System (ADS)

    Khutoryan, E. M.; Idehara, T.; Kuleshov, A. N.; Tatematsu, Y.; Yamaguchi, Y.; Matsuki, Y.; Fujiwara, T.

    2017-03-01

    In this paper, we present the results of simultaneous stabilization of both the frequency and the output power by a double PID feedback control on the acceleration and anode voltages in the 460-GHz gyrotron FU CW GVI, also known as "Gyrotron FU CW GO-1" (according to the nomenclature adopted at Osaka University). The approach used in the experiments is based on the modulation of the cyclotron frequency and the pitch factor (velocity ratio) of the electron beam by varying the acceleration and the anode voltages, respectively. In a long-term experiment, the frequency and power stabilities were made to be better than ±10-6 and ±1%, respectively.

  16. Simultaneous Stabilization of Gyrotron Frequency and Power by PID Double Feedback Control on the Acceleration and Anode Voltages

    NASA Astrophysics Data System (ADS)

    Khutoryan, E. M.; Idehara, T.; Kuleshov, A. N.; Tatematsu, Y.; Yamaguchi, Y.; Matsuki, Y.; Fujiwara, T.

    2017-07-01

    In this paper, we present the results of simultaneous stabilization of both the frequency and the output power by a double PID feedback control on the acceleration and anode voltages in the 460-GHz gyrotron FU CW GVI, also known as "Gyrotron FU CW GO-1" (according to the nomenclature adopted at Osaka University). The approach used in the experiments is based on the modulation of the cyclotron frequency and the pitch factor (velocity ratio) of the electron beam by varying the acceleration and the anode voltages, respectively. In a long-term experiment, the frequency and power stabilities were made to be better than ±10-6 and ±1%, respectively.

  17. Development of simulation tools for numerical investigation and computer-aided design (CAD) of gyrotrons

    NASA Astrophysics Data System (ADS)

    Damyanova, M.; Sabchevski, S.; Zhelyazkov, I.; Vasileva, E.; Balabanova, E.; Dankov, P.; Malinov, P.

    2016-10-01

    As the most powerful CW sources of coherent radiation in the sub-terahertz to terahertz frequency range the gyrotrons have demonstrated a remarkable potential for numerous novel and prospective applications in the fundamental physical research and the technologies. Among them are powerful gyrotrons for electron cyclotron resonance heating (ECRH) and current drive (ECCD) of magnetically confined plasma in various reactors for controlled thermonuclear fusion (e.g., tokamaks and most notably ITER), high-frequency gyrotrons for sub-terahertz spectroscopy (for example NMR-DNP, XDMR, study of the hyperfine structure of positronium, etc.), gyrotrons for thermal processing and so on. Modelling and simulation are indispensable tools for numerical studies, computer-aided design (CAD) and optimization of such sophisticated vacuum tubes (fast-wave devices) operating on a physical principle known as electron cyclotron resonance maser (ECRM) instability. During the recent years, our research team has been involved in the development of physical models and problem-oriented software packages for numerical analysis and CAD of different gyrotrons in the framework of a broad international collaboration. In this paper we present the current status of our simulation tools (GYROSIM and GYREOSS packages) and illustrate their functionality by results of numerical experiments carried out recently. Finally, we provide an outlook on the envisaged further development of the computer codes and the computational modules belonging to these packages and specialized to different subsystems of the gyrotrons.

  18. Progress in producing megawatt gyrotrons for ECR (electron cyclotron resonance) heating

    SciTech Connect

    Felch, K.; Hess, C.; Huey, H.; Jongewaard, E.; Jory, H.; Neilson, J.; Pendleton, R.; Tsirulnikov, M. )

    1990-10-01

    Varian is carrying out the development of high-power, CW gyrotrons at frequencies ranging from 100--500 GHz for use in electron cyclotron resonance (ECR) heating of magnetically-confined plasma. Initial test vehicles at 140 GHz have utilized TE{sub 15,2,1} interaction cavities, and have been designed to generate short-pulse (up to 20 ms) power levels of 1 MW and up to 400 kW CW. Recently, short-pulse power levels of 940 kW at 35% efficiency have been obtained and average powers of 200 kW have been achieved at peak powers of 400 kW. Long-pulse testing is currently underway. Initial test have resulted in output levels of 400 kW for pulse durations of 380 ms. Design work on 110 GHz, 500 kW CW gyrotron oscillators has recently been completed and a prototype tube has been assembled and is currently being tested. The design of a 110 GHz, 1 MW CW gyrotron, using a novel output coupling approach, is nearly complete. Fabrication of the first 1 MW CW experimental tube is in progress.

  19. Influence of Reflections on Frequency Tunability and Mode Competition in the Second-Harmonic THz Gyrotron

    NASA Astrophysics Data System (ADS)

    Khutoryan, Eduard M.; Idehara, Toshitaka; Melnikova, Maria M.; Ryskin, Nikita M.; Dumbrajs, Olgierd

    2017-07-01

    Effect of delayed reflection on operation of a second-harmonic terahertz (THz)-band gyrotron is studied. Theoretical analyses, numerical calculations, and experimental observations for the 0.394-THz Fukui University (FU) and continuous wave (CW) IIB gyrotron are presented. The reflections decrease starting current and expand frequency tunability range owing to excitation of high-order axial modes. They also increase frequency stability, i.e., reduce frequency change due to variation of the magnetic field. In addition, the reflections strongly affect mode competition causing suppress of the second-harmonic mode by the fundamental one and vice versa or, in the case of cooperative mode interaction, mutual power increase.

  20. Influence of Reflections on Frequency Tunability and Mode Competition in the Second-Harmonic THz Gyrotron

    NASA Astrophysics Data System (ADS)

    Khutoryan, Eduard M.; Idehara, Toshitaka; Melnikova, Maria M.; Ryskin, Nikita M.; Dumbrajs, Olgierd

    2017-03-01

    Effect of delayed reflection on operation of a second-harmonic terahertz (THz)-band gyrotron is studied. Theoretical analyses, numerical calculations, and experimental observations for the 0.394-THz Fukui University (FU) and continuous wave (CW) IIB gyrotron are presented. The reflections decrease starting current and expand frequency tunability range owing to excitation of high-order axial modes. They also increase frequency stability, i.e., reduce frequency change due to variation of the magnetic field. In addition, the reflections strongly affect mode competition causing suppress of the second-harmonic mode by the fundamental one and vice versa or, in the case of cooperative mode interaction, mutual power increase.

  1. Gyrotron: an ECH system component

    SciTech Connect

    Loring, C.M.; Eason, H.O.; Kimrey, H.D.; White, T.L.; Jory, H.R.; Evans, S.J.

    1981-01-01

    The gyrotron, or electron-cyclotron maser, in the form of a gyromonotron, is being developed as a source of millimeter wave energy for fusion plasma heating. The characteristics of this high power, high efficiency electron tube are described in terms of the requirements for the beam power supply system, the mechanical support system, the cooling system, the focusing and tuning magnets, and the waveguide system. Requirements of power level and transmission efficiency dictate the use of oversize waveguide. The implications, both to the user and to the interaction mechanisms in the gyrotron, of the use of oversize waveguide are treated. The effects of variations of various operating parameters upon the gyrotron's power output and stability are also discussed. Data from gyrotron development and system operation are used where appropriate.

  2. Development and Applications of High—Frequency Gyrotrons in FIR FU Covering the sub-THz to THz Range

    NASA Astrophysics Data System (ADS)

    Idehara, Toshitaka; Sabchevski, Svilen Petrov

    2012-07-01

    Powerful sources of coherent radiation in the sub-terahertz and in the terahertz frequency range of the electromagnetic spectrum are necessary for a great and continuously expanding number of applications in the physical research and in various advanced technological processes as well as in radars, communication systems, for remote sensing and inspection etc.. In recent years, a spectacular progress in the development of various gyro-devices and in particular of the powerful high frequency (sub-terahertz and terahertz) gyrotron oscillators has demonstrated a remarkable potential for bridging the so-called terahertz power gap and stimulated many novel and prospective applications. In this review paper we outline two series of such devices, namely the Gyrotron FU Series which includes pulsed gyrotrons and Gyrotron FU CW Series which consist of tubes operated in a CW (continuous wave) or long pulse mode, both developed at the FIR FU Center. We present the most remarkable achievements of these devices and illustrate their applications by some characteristic examples. An outlook for the further extension of the Gyrotron FU CW Series is also provided.

  3. VizieR Online Data Catalog: NIKA maps of ClG J1226.9+3332 at 150 and 250GHz (Adam+, 2015)

    NASA Astrophysics Data System (ADS)

    Adam, R. A.; Comis, B. C.; Macedas-Perez, J. F.; Adane, A.; Ade, P.; Andre, P.; Beelen, A.; Belier, B.; Benoit, A.; Bideaud, A.; Billot, N.; Blanquer, G.; Bourrion, O.; Calvo, M.; Catalano, A.; Coiffard, G.; Cruciani, A.; D'Addabbo, A.; Desert, F.-X.; Doyle, S.; Goupy, J.; Kramer, C.; Leclercq, S.; Martino, J.; Mauskopf, P.; Mayet, F.; Monfardini, A.; Pajot, F.; Pascale, E.; Perotto, L.; Pointecouteau, E.; Ponthieu, N.; Reveret, V.; Ritacco, A.; Rodriguez, L.; Savini, G.; Schuster, K.; Sievers, A.; Tucker, C.; Zylka, R.

    2015-01-01

    The surface brightness maps of CL J1226.9+3332 obtained with NIKA at the IRAM 30-meter telescope at 150 and 260GHz are presented. They were obtained during the first NIKA open pool in February 2014. The maps FWHM angular resolution is 12.0" at 250GHz and 18.2" at 150GHz. Due to the scanning strategy, the noise rms is relatively constant in the central 80" radius but rapidly increase towards the edge, being up to four times larger in the corners. Scales larger than 2' are filtered during the data reduction. The image coordinates can be found in the FITS header. Units are mJy/beam. (2 data files).

  4. Multi-Megawatt Operation of a 95 GHz Gyrotron

    NASA Astrophysics Data System (ADS)

    Felch, Kevin; Blank, Monica; Borchard, Philipp; Cahalan, Pat; Cauffman, Steve

    2010-11-01

    A 95 GHz gyrotron capable of generating CW power levels in excess of 2 MW is under development at CPI. The gyrotron employs a single-anode electron gun that produces a 90-kV, 75-A electron beam for interaction with the TE22,6,1 cavity mode. Output power from the cavity is transformed into a Gaussian beam using an internal converter that consists of a waveguide launcher and three focusing and phase-correcting mirrors. The beam exits the tube through a chemical-vapor-deposition diamond window. The spent electron beam is dissipated in a 40.6-cm diameter collector fabricated from a strengthened copper alloy. The collector nominally operates at a voltage of 61 kV relative to the cathode potential to minimize the amount of power absorbed in the collector and to improve efficiency. In tests on the gyrotron the maximum power achieved thus far is 1.72 MW with 33% efficiency at the nominal beam current of 75 A. At a reduced beam current of 45 A, an output power of 1.4 MW is obtained with over 50% efficiency. We are planning tube modifications to increase the output power level where efficiencies of greater than 50% can still be obtained.

  5. Nonstationary oscillations in gyrotrons revisited

    SciTech Connect

    Dumbrajs, O.; Kalis, H.

    2015-05-15

    Development of gyrotrons requires careful understanding of different regimes of gyrotron oscillations. It is known that in the planes of the generalized gyrotron variables: cyclotron resonance mismatch and dimensionless current or cyclotron resonance mismatch and dimensionless interaction length complicated alternating sequences of regions of stationary, periodic, automodulation, and chaotic oscillations exist. In the past, these regions were investigated on the supposition that the transit time of electrons through the interaction space is much shorter than the cavity decay time. This assumption is valid for short and/or high diffraction quality resonators. However, in the case of long and/or low diffraction quality resonators, which are often utilized, this assumption is no longer valid. In such a case, a different mathematical formalism has to be used for studying nonstationary oscillations. One example of such a formalism is described in the present paper.

  6. Review of quasi-optical gyrotron development

    NASA Astrophysics Data System (ADS)

    Fliflet, A. W.; Hargreaves, T. A.; Fischer, R. P.; Manheimer, W. M.; Sprangle, P.

    1990-03-01

    advances in the analysis and design of QOG configurations capable of efficient and stable single-mode operation are discussed, showing the possibility of achieving 50% transverse efficiency in highly overmoded resonators. The application of a depressed collector is discussed as a means of recovering the energy in the axial motion of the spent electron beam and, thus, raising the output efficiency to near the transverse electronic efficiency. The problem of high field magnet design is addressed, for both fundamental and higher harmonic operations, the latter being necessary at very high frequencies. The design equations and tradeoffs are applied to the design of 1-MW, CW quasi-optical gyrotrons operating at 120 GHz, in the first and second harmonic at 280 GHz and in the second harmonic at 560 GHz. The output coupling for these 1 MW designs is 5-7% showing the potential for even higher powers per tube if sheet-beam electron guns can be developed. The estimated electronic efficiency of the fundamental harmonic designs is 23%, which leads to an output efficiency of 47% with the use of a depressed collector with a modest collection efficiency. The peak ohmic heating density is 500 kW/cm2 in all the designs. This leads to resonator mirror separations ranging from 127 cm for 120-GHz design, to 232 cm for the 560-GHz, second harmonic design. Finally, a simple output system composed of'elliptical and parabolic mirrors is described that converts the output radiation from the resonator into a parallel, quasi-Gaussian beam. Experimental programs are reviewed as well, including the recent experiment at the Naval Research Laboratory that produced frequencies ranging from 95-130 GHz and powers up to 150 kW. Operation in a single mode was observed at powers up to 125 kW despite the resonator being highly overmoded. Comparison is made with the theoretically-predicted region of single-mode operation. Recent progress in the experimental characterization of QOG resontors is summarized.

  7. Large Scale CW ECRH Systems: Some considerations

    NASA Astrophysics Data System (ADS)

    Erckmann, V.; Kasparek, W.; Plaum, B.; Lechte, C.; Petelin, M. I.; Braune, H.; Gantenbein, G.; Laqua, H. P.; Lubiako, L.; Marushchenko, N. B.; Michel, G.; Turkin, Y.; Weissgerber, M.

    2012-09-01

    Electron Cyclotron Resonance Heating (ECRH) is a key component in the heating arsenal for the next step fusion devices like W7-X and ITER. These devices are equipped with superconducting coils and are designed to operate steady state. ECRH must thus operate in CW-mode with a large flexibility to comply with various physics demands such as plasma start-up, heating and current drive, as well as configurationand MHD - control. The request for many different sophisticated applications results in a growing complexity, which is in conflict with the request for high availability, reliability, and maintainability. `Advanced' ECRH-systems must, therefore, comply with both the complex physics demands and operational robustness and reliability. The W7-X ECRH system is the first CW- facility of an ITER relevant size and is used as a test bed for advanced components. Proposals for future developments are presented together with improvements of gyrotrons, transmission components and launchers.

  8. First experiments with gasdynamic ion source in CW mode

    SciTech Connect

    Skalyga, V. Vodopyanov, A.; Izotov, I.; Golubev, S.; Tarvainen, O.

    2016-02-15

    A new type of ECR ion source—a gasdynamic ECR ion source—has been recently developed at the Institute of Applied Physics. The main advantages of such device are extremely high ion beam current with a current density up to 600–700 emA/cm{sup 2} in combination with low emittance, i.e., normalized RMS emittance below 0.1 π mm mrad. Previous investigations were carried out in pulsed operation with 37.5 or 75 GHz gyrotron radiation with power up to 100 kW at SMIS 37 experimental facility. The present work demonstrates the first experience of operating the gasdynamic ECR ion source in CW mode. A test bench of SMIS 24 facility has been developed at IAP RAS. 24 GHz radiation of CW gyrotron was used for plasma heating in a magnetic trap with simple mirror configuration. Initial studies of plasma parameters were performed. Ion beams with pulsed and CW high voltage were successfully extracted from the CW discharge. Obtained experimental results demonstrate that all advantages of the gasdynamic source can be realized also in CW operation.

  9. Recent progress in developing a 170 GHz, 500 kW gyrotron for testing ITER transmission line components

    NASA Astrophysics Data System (ADS)

    Felch, Kevin; Blank, Monica; Borchard, Philipp; Cahalan, Pat; Cauffman, Steve

    2011-10-01

    A 170 GHz, 500 kW CW gyrotron has been developed for testing ITER transmission line components. Although specified as a 500 kW source, the electrical design has been conceived with the goal of generating up to 1 MW of continuous output power. The design employs a double-anode electron gun, an interaction cavity operating in the TE31,8 cavity mode, a three-mirror internal converter to produce a fundamental Gaussian output beam, a CVD diamond output window and a depressed collector to safely dissipate the spent electron beam power. Fabrication of the gyrotron is nearly complete and initial high-power tests will soon be carried out. Details of the gyrotron design, results of low-power tests on the internal converter and initial high-power tests will be presented.

  10. Coaxial cavities with corrugated inner conductor for gyrotrons

    SciTech Connect

    Iatrou, C.T.; Kern, S. |; Pavelyev, A.B.

    1996-01-01

    High-frequency, high-power gyrotron oscillators are under development for plasma heating in future fusion reactors. The main technological constrain in the design of a gyrotron cavity is the thermal wall loading, which must be limited to 2--3 kW/cm{sup 2} for long pulses or CW operation. This paper investigates coaxial gyrotron cavities with longitudinal slots on the inner conductor as a means to reduce the number of possible competing modes. In the analytic theory the corrugated surface is treated as a homogeneous impedance surface (impedance corrugation) to obtain simple formulas for the characteristic equation of the eigenmodes, for the electromagnetic fields and the wall losses. The developed model applies if the number of slots is sufficiently high (cutoff wavelength much larger than the corrugation period). The characteristic equation in terms of the ratio C of the outer wall radius to the inner conductor radius is solved numerically to determine a range of eigenvalues and C where the eigenvalue curves are monotonically decreasing. In such a region a cavity having its inner conductor downtapered (radius decreasing toward the cavity output) can be used to reduce the diffractive quality factors of several modes, leaving the working mode undisturbed and without favoring other modes. In addition the electromagnetic field profiles are investigated, and in particular it is shown that for certain cavity parameters a mode could have its energy concentrated close to the inner conductor. As a check on the validity of the theoretical approximations, simulations with the MAFIA code are carried out. These give good agreement with the results of the analytic equations.

  11. Progress in Increasing Gyrotron Output Power Beyond 1 MW

    NASA Astrophysics Data System (ADS)

    Felch, K.; Blank, M.; Borchard, P.; Cahalan, P.; Cauffman, S.; Jory, H.

    2009-04-01

    A 95 GHz, multi-megawatt continuous-wave (CW) gyrotron oscillator is currently under development at CPI. The gyrotron consists of a single-anode magnetron injection gun designed to operate at 75 A and 90 kV, a TE22,6 mode cylindrical interaction cavity, an internal mode converter to transform the TE22,6 mode to a Gausssian beam, an edge-cooled CVD diamond output window, and a single-stage depressed collector fabricated from a strengthened copper alloy. During the initial experimental campaign, carried out in the Summer of 2007, peak output power levels up to 1 MW at 40 A beam current were demonstrated at pulse lengths up to 5 ms. In addition, pulses up to 15 s in duration at 25 A beam current, the long-pulse limit of the CPI test stand, and 630 kW peak output power were achieved. In the Fall of 2007, modifications to the CPI test stand were made to allow for short-pulse operation up to 75 A. A second test campaign, aimed at demonstrating peak output power in excess of 1 MW, is planned for early in 2008.

  12. RF Behavior of Cylindrical Cavity Based 240 GHz, 1 MW Gyrotron for Future Tokamak System

    NASA Astrophysics Data System (ADS)

    Kumar, Nitin; Singh, Udaybir; Bera, Anirban; Sinha, A. K.

    2017-07-01

    In this paper, we present the RF behavior of conventional cylindrical interaction cavity for 240 GHz, 1 MW gyrotron for futuristic plasma fusion reactors. Very high-order TE mode is searched for this gyrotron to minimize the Ohmic wall loading at the interaction cavity. The mode selection process is carried out rigorously to analyze the mode competition and design feasibility. The cold cavity analysis and beam-wave interaction computation are carried out to finalize the cavity design. The detail parametric analyses for interaction cavity are performed in terms of mode stability, interaction efficiency and frequency. In addition, the design of triode type magnetron injection gun is also discussed. The electron beam parameters such as velocity ratio and velocity spread are optimized as per the requirement at interaction cavity. The design studies presented here confirm the realization of CW, 1 MW power at 240 GHz frequency at TE46,17 mode.

  13. Problem-Oriented Simulation Packages and Computational Infrastructure for Numerical Studies of Powerful Gyrotrons

    NASA Astrophysics Data System (ADS)

    Damyanova, M.; Sabchevski, S.; Zhelyazkov, I.; Vasileva, E.; Balabanova, E.; Dankov, P.; Malinov, P.

    2016-05-01

    Powerful gyrotrons are necessary as sources of strong microwaves for electron cyclotron resonance heating (ECRH) and electron cyclotron current drive (ECCD) of magnetically confined plasmas in various reactors (most notably ITER) for controlled thermonuclear fusion. Adequate physical models and efficient problem-oriented software packages are essential tools for numerical studies, analysis, optimization and computer-aided design (CAD) of such high-performance gyrotrons operating in a CW mode and delivering output power of the order of 1-2 MW. In this report we present the current status of our simulation tools (physical models, numerical codes, pre- and post-processing programs, etc.) as well as the computational infrastructure on which they are being developed, maintained and executed.

  14. High time resolution observations of the polar stratosphere and mesosphere using a ground-based 230-250 GHz microwave radiometer

    NASA Astrophysics Data System (ADS)

    Newnham, D. A.; Espy, P. J.; Clilverd, M. A.; Maxfield, D. J.; Hartogh, P.; Holmén, K.; Blindheim, S.; Horne, R. B.

    2012-04-01

    Microwave radiometry is used to measure thermal emission by the Doppler- and pressure-broadened molecular rotational lines of atmospheric gases, from which vertical abundance profiles can be determined. Since solar radiation is not required for the measurement, the technique has the advantage that continuous observations are possible including throughout the polar winter. We describe the development of a passive microwave radiometer [Espy, P. J., P. Hartogh, and K. Holmen (2006), Proc. SPIE, 6362, 63620P, doi:10.1117/12.688953] for ground-based remote sensing of the polar middle atmosphere. The instrument measures nitric oxide (NO), ozone (O3), and carbon monoxide (CO) vertical profiles over the altitude range 35-90 km with time resolution as high as 15 minutes, allowing the diurnal variability of trace chemical species to be investigated. Heterodyne detection of atmospheric emission at 230 GHz and 250 GHz (wavelength ~1.25 mm) with a receiver noise temperature of 300 K is achieved using a superconductor-insulator-superconductor (SIS) mixer cooled to 4 K. The down-converted signals at 1.35 GHz and 2.10 GHz are analysed using both a moderate-resolution (28 kHz, 220 MHz bandwidth) and a high-resolution (14 kHz, 40 MHz bandwidth) chirp-transform spectrometer (CTS). The instrument was operated semi-autonomously at Troll station (72° 01'S 02° 32'E, 1270 m above sea level), Antarctica during 2008-10 and at the Arctic LIDAR Observatory for Middle Atmosphere Research (ALOMAR, 69° 16'N, 16° 00'E, 380 m above sea level), northern Norway during 2011-12. NO volume mixing ratio (VMR) profiles have been inverted from calibrated brightness temperature spectra of the NO line centred at 250.796 GHz, observed above Troll station, using the Microwave Observation Line Estimation and Retrieval (MOLIERE) version 5 code. A priori pressure, temperature, ozone, water vapour, and NO profiles above 30 km were calculated using the Sodankylä Ion and Neutral Chemistry (SIC, version 6

  15. Design of a 3-MW 140-GHz gyrotron with a coaxial cavity

    SciTech Connect

    Read, M.E.; Nusinovich, G.S.; Dumbrajs, O.; Bird, G.; Hogge, J.P.; Kreischer, K.; Blank, M.

    1996-06-01

    Gyrotrons have been developed as sources of high-power millimeter wave radiation for electron cyclotron heating for more than two decades, with orders of magnitude increases in power at frequencies to almost 300 GHz having been achieved. The requirement is for at least 1 MW, essentially CW at 110 GHz, for near-term applications such as plasma heating experiments, and greater than 1 MW CW for the next generation magnetic fusion device, the International Thermonuclear Experimental Reactor (ITER). For increased economy, multimegawatt devices are being considered. In this paper, a design for a 3-MW 140 GHz gyrotron based on the use of a coaxial cavity is given. The cavity mode is TE{sub 21,13}, chosen so that the ohmic heating on both the inner and outer conductors would be low enough for CW operation. The mode selection process, nonlinear, multimode and time-dependent modeling of the beam wave interaction, and gun design are discussed in detail. An inverted magnetron injection gun (MIG) is used to accommodate the inner conductor. The radiation is coupled out via a quasi-optical mode converter, consisting of an irregular cylindrical waveguide section followed by a step-cut launching aperture and a single near-parabolic mirror. The design of these components is also described.

  16. Continuous-Wave Operation of a Frequency-Tunable 460-GHz Second-Harmonic Gyrotron for Enhanced Nuclear Magnetic Resonance

    PubMed Central

    Torrezan, Antonio C.; Han, Seong-Tae; Mastovsky, Ivan; Shapiro, Michael A.; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Barnes, Alexander B.; Griffin, Robert G.

    2011-01-01

    The design, operation, and characterization of a continuous-wave (CW) tunable second-harmonic 460-GHz gyrotron are reported. The gyrotron is intended to be used as a submillimeter-wave source for 700-MHz nuclear magnetic resonance experiments with sensitivity enhanced by dynamic nuclear polarization. The gyrotron operates in the whispering-gallery mode TE11,2 and has generated 16 W of output power with a 13-kV 100-mA electron beam. The start oscillation current measured over a range of magnetic field values is in good agreement with theoretical start currents obtained from linear theory for successive high-order axial modes TE11,2,q. The minimum start current is 27 mA. Power and frequency tuning measurements as a function of the electron cyclotron frequency have also been carried out. A smooth frequency tuning range of 1 GHz was obtained for the operating second-harmonic mode either by magnetic field tuning or beam voltage tuning. Long-term CW operation was evaluated during an uninterrupted period of 48 h, where the gyrotron output power and frequency were kept stable to within ±0.7% and ±6 ppm, respectively, by a computerized control system. Proper operation of an internal quasi-optical mode converter implemented to transform the operating whispering-gallery mode to a Gaussian-like beam was also verified. Based on the images of the gyrotron output beam taken with a pyroelectric camera, the Gaussian-like mode content of the output beam was computed to be 92% with an ellipticity of 12%. PMID:21243088

  17. Continuous-Wave Operation of a Frequency-Tunable 460-GHz Second-Harmonic Gyrotron for Enhanced Nuclear Magnetic Resonance

    PubMed Central

    Torrezan, Antonio C.; Han, Seong-Tae; Mastovsky, Ivan; Shapiro, Michael A.; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Griffin, Robert G.; Barnes, Alexander B.

    2012-01-01

    The design, operation, and characterization of a continuous-wave (CW) tunable second-harmonic 460-GHz gyrotron are reported. The gyrotron is intended to be used as a submillimeter-wave source for 700-MHz nuclear magnetic resonance experiments with sensitivity enhanced by dynamic nuclear polarization. The gyrotron operates in the whispering-gallery mode TE11,2 and has generated 16 W of output power with a 13-kV 100-mA electron beam. The start oscillation current measured over a range of magnetic field values is in good agreement with theoretical start currents obtained from linear theory for successive high-order axial modes TE11,2,q. The minimum start current is 27 mA. Power and frequency tuning measurements as a function of the electron cyclotron frequency have also been carried out. A smooth frequency tuning range of 1 GHz was obtained for the operating second-harmonic mode either by magnetic field tuning or beam voltage tuning. Long-term CW operation was evaluated during an uninterrupted period of 48 h, where the gyrotron output power and frequency were kept stable to within ±0.7% and ±6 ppm, respectively, by a computerized control system. Proper operation of an internal quasi-optical mode converter implemented to transform the operating whispering-gallery mode to a Gaussian-like beam was also verified. Based on the images of the gyrotron output beam taken with a pyroelectric camera, the Gaussian-like mode content of the output beam was computed to be 92% with an ellipticity of 12%. PMID:23761938

  18. Mutual synchronization of weakly coupled gyrotrons

    SciTech Connect

    Rozental, R. M.; Glyavin, M. Yu.; Sergeev, A. S.; Zotova, I. V.; Ginzburg, N. S.

    2015-09-15

    The processes of synchronization of two weakly coupled gyrotrons are studied within the framework of non-stationary equations with non-fixed longitudinal field structure. With the allowance for a small difference of the free oscillation frequencies of the gyrotrons, we found a certain range of parameters where mutual synchronization is possible while a high electronic efficiency is remained. It is also shown that synchronization regimes can be realized even under random fluctuations of the parameters of the electron beams.

  19. The First Decade of the Gyrotronics

    NASA Astrophysics Data System (ADS)

    Petelin, M. I.

    2017-07-01

    Our review (Nusinovich et al. Journal of Infrared, Millimeter, and Terahertz Waves, 35, 325, 2014) proved to be of interest for gyrotron researchers, gyrotron users, and specialists in neighboring fields of physics but underwent a fair criticism for a number of historical omissions. So my co-authors G. S. Nusinovich and M. K. A. Thumm advised me to supplement our paper (Nusinovich et al. Journal of Infrared, Millimeter, and Terahertz Waves, 35, 325, 2014) with the following memoir.

  20. The Gyrotron at 50: Historical Overview

    NASA Astrophysics Data System (ADS)

    Nusinovich, Gregory S.; Thumm, Manfred K. A.; Petelin, Michael I.

    2014-04-01

    Gyrotrons form a specific group of devices in the class of fast-wave vacuum electronic sources of coherent electromagnetic wave radiation known as electron cyclotron masers (ECMs) or cyclotron resonance masers (CRMs). The operation of CRMs is based on the cyclotron maser instability which originates from the relativistic dependence of the electron cyclotron frequency on the electron energy. This relativistic effect can be pronounced even at low voltages when the electron kinetic energy is small in comparison with the rest energy. The free energy for generation of electromagnetic (EM) waves is the energy of electron gyration in an external magnetic field. As in any fast-wave device, the EM field in a gyrotron interaction space is not localized near a circuit wall (like in slow-wave devices), but can occupy large volumes. Due to possibilities of using various methods of mode selection (electrodynamical and electronic ones), gyrotrons can operate in very high order modes. Since the use of large, oversized cavities and waveguides reduces the role of ohmic wall losses and breakdown limitations, gyrotrons are capable of producing very high power radiation at millimeter and submillimeter wavelengths. The present review is restricted primarily by the description of the development and the present state-of-the-art of gyrotrons for controlled thermonuclear fusion plasma applications. The first gyrotron was invented, designed and tested in Gorky, USSR (now Nizhny Novgorod, Russia), in 1964.

  1. Initial operation of a high-power whispering-gallery-mode gyrotron

    SciTech Connect

    Felch, K.; Ives, L.; Jongewaard, E.; Jory, H.; Spang, S.

    1987-10-01

    Varian has begun the development of a high-power gyrotron based on a whispering-gallery-mode interaction circuit. The first experimental tube has been designed to generate pulsed output powers up to 1 MW at a frequency of 140 GHz. The tube was also designed for CW operation at power levels of several hundred kilowatts. The overall design of the tube is discussed. Fabrication of the tube is nearing completion and initial tests on the tube will be carried out in the near future. 5 refs., 2 figs.

  2. Development of High Power Gyrotrons at 84, 110, and 140 GHz

    NASA Astrophysics Data System (ADS)

    Cauffman, Stephen; Blank, Monica; Borchard, Philipp; Cahalan, Pat; Chu, Sam; Felch, Kevin; Jory, Howard

    2002-11-01

    High power mm-wave sources are needed for electron cyclotron heating, current drive, and instability suppression in fusion plasmas. CPI has recently developed an 84 GHz, 500 kW, 2 second pulse gyrotron for use on K-STAR; a series of 110 GHz, 1 MW, 10 second pulse gyrotrons (two of which had achieved 1 MW 5 second pulse widths as of the writing of this abstract) for use on DIII-D; and a 140 GHz, 1 MW, CW gyrotron (for which initial tests were conducted, and which is presently being modified in preparation for further testing) for use on W-7X. Each design employs a diode magnetron injection gun, a high-order TE-mode interaction cavity, an internal mode converter to transform the excitation mode into a Gaussian output beam, and a CVD diamond output window to allow low- loss transmission of the output beam. The 84 GHz and 140 GHz systems employ a single-stage depressed voltage beam collector to enhance the overall electrical efficiency of the device and an external high voltage layout that obviates the need for oil insulation. Experimental results for each system will be discussed.

  3. High Power Operation of a 170 GHz Gyrotron for ITER

    NASA Astrophysics Data System (ADS)

    Kreischer, Kenneth E.

    1996-11-01

    Recent experiments at MIT (In collaboration with B.G. Danly, T. Kimura, and R.J. Temkin) on a megawatt gyrotron designed for ITER have achieved record powers at 170.1 GHz. Single mode emission with a peak output power of 1.5 MW and an efficiency of 35% has been measured. The MIT gyrotron operates for 3 μsec pulses at 2 Hz but has been designed to model long pulse or cw operation. The experiment is based on a resonant cylindrical cavity operating in the TE_28,8,1 mode that is situated in the bore of a 6.7 T magnet. It is necessary to operate in a very high order mode in order to reduce cavity ohmic losses to levels that can be adequately cooled (about 1 kW/cm^2). The microwaves are generated in the cavity by an 83 kV annular electron beam produced by a triode-type magnetron injection gun that is capable of currents up to 50 A. Megawatt power levels with efficiencies between 30-35% have been measured over a wide range of operating parameters for the TE_28,8,1 mode. Similar results were also achieved in the neighboring TE_27,8,1 mode at 166.6 GHz, and the TE_29,8,1 mode at 173.5 GHz. These results are in good agreement with nonlinear multimode simulations of the cavity. (S.Y. Cai, T.M. Antonsen, G. Saraph, and B. Levush, Int. J. Electronics, Vol. 72, 759-777 (1992).) The high output power is the result of a carefully designed electron gun that is less sensitive than previous guns to misalignment, and a novel cavity that is less prone to mode competition. The gun was built by C.P.I. (formerly Varian Associates), and has a low perpendicular velocity spread (6-10%). The cavity, which was designed in collaboration with the University of Maryland, uses an output iris to increase the diffraction Q while keeping the interaction length short. Future plans include the installation of an internal mode converter that will transform the TE_28,8,1 mode into a Gaussian beam, and the use of a depressed collector to increase the device efficiency above 50%. The successful

  4. Development of problem-oriented software packages for numerical studies and computer-aided design (CAD) of gyrotrons

    NASA Astrophysics Data System (ADS)

    Damyanova, M.; Sabchevski, S.; Zhelyazkov, I.; Vasileva, E.; Balabanova, E.; Dankov, P.; Malinov, P.

    2016-03-01

    Gyrotrons are the most powerful sources of coherent CW (continuous wave) radiation in the frequency range situated between the long-wavelength edge of the infrared light (far-infrared region) and the microwaves, i.e., in the region of the electromagnetic spectrum which is usually called the THz-gap (or T-gap), since the output power of other devices (e.g., solid-state oscillators) operating in this interval is by several orders of magnitude lower. In the recent years, the unique capabilities of the sub-THz and THz gyrotrons have opened the road to many novel and future prospective applications in various physical studies and advanced high-power terahertz technologies. In this paper, we present the current status and functionality of the problem-oriented software packages (most notably GYROSIM and GYREOSS) used for numerical studies, computer-aided design (CAD) and optimization of gyrotrons for diverse applications. They consist of a hierarchy of codes specialized to modelling and simulation of different subsystems of the gyrotrons (EOS, resonant cavity, etc.) and are based on adequate physical models, efficient numerical methods and algorithms.

  5. Large Scale CW ECRH Systems: Meeting a Challenge

    SciTech Connect

    Erckmann, V.; Braune, H.; Laqua, H. P.; Marushchenko, N. B.; Michel, G.; Kasparek, W.; Plaum, B.; Lechte, C.; Stuttgart, IPF; Petelin, M. I.; Lubiako, L.; Bruschi, A.; D'Arcangelo, O.; Bin, W.; Van Den Braber, R.; Doelman, N.; Gantenbein, G.; Thumm, M.

    2011-12-23

    Electron Cyclotron Resonance Heating (ECRH) systems for next step-fusion devices like W7-X and ITER operate in CW-mode and provide a large flexibility to comply with various physics demands such as plasma start-up, heating and current drive, as well as configuration and MHD control. The request for many different sophisticated applications results in a growing complexity of the systems. This is in conflict with the request for high availability, reliability, and maintainability, which arises from DEMO demands. 'Advanced' ECRH-components must, therefore, comply with both the complex physics demands and operational robustness and reliability. The W7-X ECRH system is the first CW facility of an ITER relevant size and is used as a test bed for such components. Results on improvements of gyrotrons, transmission components and launchers are presented together with proposals for future developments.

  6. Electron-optical systems for planar gyrotrons

    NASA Astrophysics Data System (ADS)

    Manuilov, V. N.; Zaslavsky, V. Yu.; Ginzburg, N. S.; Glyavin, M. Yu.; Kuftin, A. N.; Zotova, I. V.

    2014-02-01

    The methodology of designing an electron-optical system (EOS) that forms sheet helical electron beams (HEBs) for high-power gyrotrons is developed. As an example, we consider the EOS for a 140-GHz gyrotron operated at the first harmonic of the cyclotron frequency with an accelerating voltage of 50 kV, a beam current of 30 A, and a magnetic field compression of 36. A planar geometry of the magnetron-injection gun (MIG) is suggested. The adiabatic theory of MIGs modified for the planar geometry of EOS is used for preliminary estimations of MIG parameters. Numerical simulation of the HEB properties based on the CST STUDIO SUITE 3D code is performed to find the optimal configuration of a planar MIG. The accuracy of the calculated data is discussed. The main factors that affect the HEB quality are considered. It is shown that a sheet HEB with a pitch-factor of 1.3 and velocity spread not exceeding 25%-30% can be formed; this is quite acceptable for high-efficiency operation of modern gyrotrons. Calculation of the beam-wave interaction with the obtained HEB parameters proved that a high output power with a sufficiently good efficiency of about 20% can be reached. Simulations show the feasibility of the experimental implementation of a novel planar EOS and its use in short-wave planar gyrotrons. The developed technique can be used for the study and optimization of planar gyrotrons of different frequency bands and power levels.

  7. ECH by FEL and gyrotron sources on the Microwave Tokamak Experiment (MTX) tokamak

    SciTech Connect

    Stallard, B.W.; Turner, W.C.; Allen, S.L.; Byers, J.A.; Felker, B.; Fenstermacher, M.E.; Ferguson, S.W.; Hooper, E.G.; Thomassen, K.I.; Throop, A.L. ); Makowski, M.A. )

    1990-08-09

    The Microwave Tokamak Experiment (MTX) at LLNL is studying the physics of intense pulse ECH is a high-density tokamak plasma using a microwave FEL. Related technology development includes the FEL, a windowless quasi-optical transmission system, and other microwave components. Initial plasma experiments have been carried out at 140 GHz with single rf pulses generated using the ETA-II accelerator and the ELF wiggler. Peak power levels up to 0.2 GW and pulse durations up to 10 ns were achieved for injection into the plasma using as untapered wiggler. FEL pulses were transmitted over 33 m from the FEL to MTX using six mirrors mounted in a 50-cm-diam evacuated pipe. Measurements of the microwave beam and transmission through the plasma were carried out. For future rapid pulse experiments at high average power (4 GW peak power, 5kHz pulse rate, and {bar P} > 0.5 MW) using the IMP wiggler with tapered magnetic field, a gyrotron (140 GHz, 400 kW cw or up to 1 MW short pulse) is being installed to drive the FEL input or to directly heat the tokamak plasma at full gyrotron power. Quasi-optic techniques will be used to couple the gyrotron power. For direct plasma heating, the gyrotron will couple into the existing mirror transport system. Using both sources of rf generation, experiments are planned to investigate intense pulse absorption and tokamak physics, such as the ECH of a pellet-fueled plasma and plasma control using localized heating. 12 refs., 9 figs.

  8. Final Report for "Gyrotron Design and Evaluation using New Particle-in-Cell Capability"

    SciTech Connect

    David N Smithe

    2008-05-28

    ITER will depend on high power CW gyrotrons to deliver power to the plasma at ECR frequencies. However, gyrotrons can suffer from undesirable low frequency oscillations (LFO’s) which are known to interfere with the gun-region diagnostics and data collection, and are also expected to produce undesirable energy and velocity spread in the beam. The origins and processes leading to these oscillations are poorly understood, and existing gyrotron R&D tools, such as static gun solvers and interaction region models, are not designed to look at time-dependant oscillatory behavior. We have applied a time-domain particle-in-cell method to investigate the LFO phenomenon. Our company is at the forefront of smooth-curved-boundary treatment of the electromagnetic fields and particle emission surfaces, and such methods are necessary to simulate the adiabatically trapped and reflected electrons thought to be driving the oscillations. This approach provides the means for understanding, in microscopic detail, the underlying physical processes driving the low-frequency oscillations. In the Phase I project, an electron gun region from an existing gyrotron, known to observe LFO’s, was selected as a proof-of-principle geometry, and was modeled with the curved-geometry time-domain simulation tool, in order to establish the feasibility of simulating LFO physics with this tool on office-scale, and larger, parallel cluster computers. Generally, it was found to be feasible to model the simulation geometry, emission, and magnetic features of the electron gun. Ultimately, the tool will be used to investigate the origins and life cycle within the trapped particle population. This tool also provides the foundations and validation for potential application of the software to numerous other time-dependant beam and rf source problems in the commercial arena.

  9. ECH by FEL and gyrotron sources on the Microwave Tokamak Experiment (MTX) tokamak

    NASA Astrophysics Data System (ADS)

    Stallard, B. W.; Turner, W. C.; Allen, S. L.; Byers, J. A.; Felker, B.; Fenstermacher, M. E.; Ferguson, S. W.; Hooper, E. G.; Thomassen, K. I.; Throop, A. L.

    1990-08-01

    The Microwave Tokamak Experiment (MTX) at LLNL is studying the physics of intense pulse ECH is a high-density tokamak plasma using a microwave FEL. Related technology development includes the FEL, a windowless quasi-optical transmission system, and other microwave components. Initial plasma experiments have been carried out at 140 GHz with single RF pulses generated using the ETA-2 accelerator and the ELF wiggler. Peak power levels up to 0.2 GW and pulse durations up to 10 ns were achieved for injection into the plasma using as untapered wiggler. FEL pulses were transmitted over 33 m from the FEL to MTX using six mirrors mounted in a 50 cm diam evacuated pipe. Measurements of the microwave beam and transmission through the plasma were carried out. For future rapid pulse experiments at high average power (4 GW peak power, 5 kHz pulse rate, and bar P is greater than 0.5 MW) using the IMP wiggler with tapered magnetic field, a gyrotron (140 GHz, 400 kW CW or up to 1 MW short pulse) is being installed to drive the FEL input or to directly heat the tokamak plasma at full gyrotron power. Quasi-optic techniques will be used to couple the gyrotron power. For direct plasma heating, the gyrotron will couple into the existing mirror transport system. Using both sources of RF generation, experiments are planned to investigate intense pulse absorption and tokamak physics, such as the ECH of a pellet-fueled plasma and plasma control using localized heating.

  10. Linear theory of frequency pulling in gyrotrons

    SciTech Connect

    Nusinovich, Gregory S.; Luo, Li; Liu, Pu-Kun

    2016-05-15

    The effect of the electron beam on the gyrotron operating frequency (the frequency pulling) is studied analytically in the framework of the linear (or small-signal) theory. The theory is applicable for gyrotrons operating at any cyclotron harmonics and in modes with arbitrary axial structures. The present consideration is limited to cases of operation at the fundamental cyclotron resonance and the second harmonic; also two specific axial profiles of the resonator modes are analyzed: the constant and the sinusoidal distributions. In the case of the sinusoidal distribution, we considered the operation in modes with one, two, and three axial variations. It is shown how to use the theory developed for analyzing the frequency tunability due to the frequency pulling effect in a gyrotron with specified parameters of the electron beam.

  11. Compact, harmonic multiplying gyrotron amplifiers

    SciTech Connect

    Guo, H.Z.; Granatstein, V.L.; Antonsen, T.M. Jr.; Levush, B.; Tate, J.; Chen, S.H.

    1995-12-31

    A compact, harmonic multiplying gyrotron traveling wave amplifier is being developed. The device is a three-stage tube with the output section running as a fourth harmonic gyro-TWT, the input section running as a fundamental gyro-TWT, and the middle operating at the second harmonic of the cyclotron frequency. Radiation is suppressed by servers between the sections. The operating beam of the tube is produced by a magnetron injection gun (MIG). A TE{sub 0n} mode selective interaction circuit consisting of mode converters and a filter waveguide is employed for both input and output sections to solve the mode competition problem, which is pervasive in gyro-TWT operation. The input section has an input coupler designed as a TE{sub 0n} mode launcher. It excites a signal at the fundamental cyclotron frequency (17.5 GHz), which is amplified in the first TWT interaction region. So far the device is similar to a two-stage harmonic gyro-TWT. The distinction is that in the three-stage device the second section will be optimized not for output power but for fourth harmonic bunching of the beam. A gyroklystron amplifier has also been designed. The configuration is similar to the gyro-TWT but with the traveling wave interaction structures replaced by mode selective special complex cavities. Cold test results of the wideband input coupler and the TE{sub 0n} mode selective interaction circuit have been obtained.

  12. New trends in gyrotron development

    NASA Astrophysics Data System (ADS)

    Denisov, G. G.

    2017-08-01

    Gyro-devices provide the highest CW or average power of microwaves in centimeter, millimeter and submillimeter wavelength ranges and therefore they are very attractive as microwave sources for many of applications such as plasma fusion, radiolocation, ion sources, telecommunication, technology, spectroscopy and some other. In last years an essential progress in the device development was demonstrated. The paper presents State-of the Art in the device development, new demands in the parameters enhancement and possible ways to achieve the goals.

  13. Electron gun simulation for 95 GHz gyrotron

    SciTech Connect

    Singh, Udaybir; Kumar, Nitin; Sinha, A.K. E-mail: aksinha@ceeri.ernet.in; Purohit, L.P.

    2011-07-01

    A triode type Magnetron Injection Gun (MIG) for a 2 MW, 95 GHz Gyrotron has been designed by using commercially available code EGUN and another in-house developed code MIGANS. The operating mode of the gyrotron is TE{sub 24.8} and it is operated in the fundamental harmonic. The operating voltages of the modulating anode and the accelerating anode are 61 kV and 85 kV respectively. The parametric dependences of modulating anode voltage and cathode magnetic field on the beam quality have also been studied. (author)

  14. A review on the sub-THz/THz gyrotrons

    NASA Astrophysics Data System (ADS)

    Kumar, Nitin; Singh, Udaybir; Bera, Anirban; Sinha, A. K.

    2016-05-01

    A review on the sub-THz/THz gyrotrons is performed in this manuscript. The present development status of gyrotrons can be divided into three streams for the sake of better understanding: 1. low frequency (<35 GHz), medium power (<100 kW), small size and easy to handle gyrotrons for industrial applications, 2. very high power (1 MW or more), medium frequency (100-200 GHz) gyrotrons for plasma fusion applications, 3. low power (few tens of watt to kW), high frequency (>200 GHz) gyrotrons for various innovative applications. In this manuscript, the third stream of gyrotron development is reviewed. In last few decades several innovative applications are searched in sub-THz/THz band where the gyrotrons could be used as an efficient source of RF radiation. The applications of sub-THz/THz gyrotrons including the futuristic scope of the device are also discussed in this article. Further, several criticalities arise in the design and development when the gyrotron operation shifts toward the high frequency band. Various such design and technological challenges are also discussed here. Finally the development status of sub-THz/THz gyrotrons as per the use in various scientific and technological applications is also discussed.

  15. Electron-optical systems for planar gyrotrons

    SciTech Connect

    Manuilov, V. N.; Zaslavsky, V. Yu.; Ginzburg, N. S.; Glyavin, M. Yu.; Kuftin, A. N.; Zotova, I. V.

    2014-02-15

    The methodology of designing an electron-optical system (EOS) that forms sheet helical electron beams (HEBs) for high-power gyrotrons is developed. As an example, we consider the EOS for a 140-GHz gyrotron operated at the first harmonic of the cyclotron frequency with an accelerating voltage of 50 kV, a beam current of 30 A, and a magnetic field compression of 36. A planar geometry of the magnetron-injection gun (MIG) is suggested. The adiabatic theory of MIGs modified for the planar geometry of EOS is used for preliminary estimations of MIG parameters. Numerical simulation of the HEB properties based on the CST STUDIO SUITE 3D code is performed to find the optimal configuration of a planar MIG. The accuracy of the calculated data is discussed. The main factors that affect the HEB quality are considered. It is shown that a sheet HEB with a pitch-factor of 1.3 and velocity spread not exceeding 25%–30% can be formed; this is quite acceptable for high-efficiency operation of modern gyrotrons. Calculation of the beam-wave interaction with the obtained HEB parameters proved that a high output power with a sufficiently good efficiency of about 20% can be reached. Simulations show the feasibility of the experimental implementation of a novel planar EOS and its use in short-wave planar gyrotrons. The developed technique can be used for the study and optimization of planar gyrotrons of different frequency bands and power levels.

  16. On optimization of sub-THz gyrotron parameters

    SciTech Connect

    Dumbrajs, O.; Nusinovich, G. S.

    2012-10-15

    The theory is developed describing how the optimization of gyrotron parameters should be done taking into account two effects deteriorating the gyrotron efficiency: the spread in electron velocities and the spread in the guiding center radii. The paper starts from qualitative analysis of the problem. This simplified theory is used for making some estimates for a specific gyrotron design. The same design is then studied by using more accurate numerical methods. Results of the latter treatment agree with former qualitative predictions.

  17. Analysis of cavity and window for THz gyrotron

    SciTech Connect

    Alaria, Mukesh Kumar; Mukherjee, P.; Rao, R.R.; Sinha, A.K. E-mail: aksinha@ceeri.ernet.in

    2011-07-01

    In this paper study of cavity and window has been carried out using Ansoft HFSS for Terahertz Gyrotron. Eigen mode analysis of the cavity has been carried out at 1 THz. An idea about the operating modes in the cavity of the Gyrotron and obtained the simulated Eigen frequency and field pattern of the modes. The design of window for 1 THz Gyrotron has also been carried out using HFSS. The simulated results have also been compared with ST microwave studio. (author)

  18. Theory and Modeling of High-Power Gyrotrons

    SciTech Connect

    Nusinovich, Gregory Semeon

    2016-04-29

    This report summarized results of the work performed at the Institute for Research in Electronics and Applied Physics of the University of Maryland (College Park, MD) in the framework of the DOE Grant “Theory and Modeling of High-Power Gyrotrons”. The report covers the work performed in 2011-2014. The research work was performed in three directions: - possibilities of stable gyrotron operation in very high-order modes offering the output power exceeding 1 MW level in long-pulse/continuous-wave regimes, - effect of small imperfections in gyrotron fabrication and alignment on the gyrotron efficiency and operation, - some issues in physics of beam-wave interaction in gyrotrons.

  19. High harmonic terahertz confocal gyrotron with nonuniform electron beam

    SciTech Connect

    Fu, Wenjie; Guan, Xiaotong; Yan, Yang

    2016-01-15

    The harmonic confocal gyrotron with nonuniform electron beam is proposed in this paper in order to develop compact and high power terahertz radiation source. A 0.56 THz third harmonic confocal gyrotron with a dual arc section nonuniform electron beam has been designed and investigated. The studies show that confocal cavity has extremely low mode density, and has great advantage to operate at high harmonic. Nonuniform electron beam is an approach to improve output power and interaction efficiency of confocal gyrotron. A dual arc beam magnetron injection gun for designed confocal gyrotron has been developed and presented in this paper.

  20. Electron-Optical System of the Gyrotron Designed for Operation in the DNP-NMR Spectrometer Cryomagnet ("Gyrotrino")

    NASA Astrophysics Data System (ADS)

    Bratman, V. L.; Fedotov, A. E.; Kalynov, Yu. K.; Manuilov, V. N.

    2017-08-01

    The formation and utilization of a helical electron beam are studied theoretically for a gyrotron with a very low operating voltage in a range 1.5-1.8 kV. Such a gyrotron ("gyrotrino") was earlier proposed for operation inside a magnetic system of an NMR spectrometer with a dynamic nuclear polarization upgrade. Despite the very low voltage, the optimization of the electrode shape can provide velocity and positional electron spreads not exceeding these values for conventional high-voltage gyrotrons. A very small cathode-anode separation makes the gyrotrino very sensitive to thermal expansion of the gun elements that should be compensated by movement of the cathode. Estimations for long-pulse and CW regimes of the gyrotrino operation show that the ion background significantly decreases the reduction of the beam potential and leads to an acceptable drift of the electron cyclotron frequency at the voltage front. A satisfactory thermal load on the waste-beam collector located in a strong uniform magnetic field can be achieved due to the omnidirectional heat flow regime occurring in the case of thin beam footprint.

  1. Gyrotron-Based Microwave Sintering of Ceramics

    NASA Astrophysics Data System (ADS)

    Fliflet, A. W.; Bruce, R. W.; Fischer Lewis, R. P., III; Bender, B. A.; Chow, G.-M.; Rayne, R. J.; Kurihara, L. K.; Schoen, P. E.

    1997-11-01

    The development of powerful gyrotrons has opened up the millimeter-wave regime (>= 28 GHz) for processing ceramic materials. A number of studies of microwave sintering of ceramics have indicated that sintering proceeds much faster in microwave furnaces than in conventional furnaces, however, specific conclusions have been limited by the wide range of materials investigated and measurement difficulties. To assess the potential of high frequency microwave sintering, and to investigate the possibility of a specific microwave mechanism, the Naval Research Laboratory has recently undertaken a systematic study focused on the sintering of fine and ultra-fine grained alumina and titania compacts. This paper presents 35 GHz microwave sintering data obtained using a gyrotron-powered furnace and compares our data with results from other microwave and conventional sintering studies.

  2. Continuously tunable, split-cavity gyrotrons

    NASA Astrophysics Data System (ADS)

    Brand, G. F.; Gross, M.

    1985-12-01

    Attention is given to a gyrotron cavity configuration which is split in halves longitudinally, to allow any frequency lying between the fixed cavity resonance to be assessed by mechanically changing the separation of the two halves. Experimental results are presented which demonstrate that the rate-of-change in resonant frequency with separation is greatest if the minor axis of the cavity cross section is the one undergoing change. Excellent agreement with theory is noted for these results.

  3. Wide Band Gyrotron Traveling Wave Amplifier Analysis.

    DTIC Science & Technology

    1987-12-01

    phase versus frequency characteristics. It is in these aspects that the gyrotron amplifier effort has been less than successful. A C-band gyro- TWT ...proposals were made several years ago, no experimental results have yet been reported. Another concept for increasing the bandwidth of the gyro- TWT is to...including dielectric loading of the waveguide [24], helix loaded waveguide (25]-[26], and disc-loaded waveguide [26]-(27). No experimental results on

  4. Improved Collectors for High Power Gyrotrons

    SciTech Connect

    Ives, R. Lawrence; Singh, Amarjit; Read, Michael; Borchard, Phillipp; Neilson, Jeff

    2009-05-20

    High power gyrotrons are used for electron cyclotron heating, current drive and parasitic mode suppression in tokamaks for fusion energy research. These devices are crucial for successful operation of many research programs around the world, including the ITER program currently being constructed in France. Recent gyrotron failures resulted from cyclic fatigue of the copper material used to fabricated the collectors. The techniques used to collect the spent beam power is common in many gyrotrons produced around the world. There is serious concern that these tubes may also be at risk from cyclic fatigue. This program addresses the cause of the collector failure. The Phase I program successfully demonstrated feasibility of a mode of operation that eliminates the cyclic operation that caused the failure. It also demonstrated that new material can provide increased lifetime under cyclic operation that could increase the lifetime by more than on order of magnitude. The Phase II program will complete that research and develop a collector that eliminates the fatigue failures. Such a design would find application around the world.

  5. Collective scattering of gyrotron radiation for T/sub i/ measurements on EBT

    SciTech Connect

    Bighel, L.; White, T.L.

    1981-02-01

    For T/sub i/ measurements in EBT, 90/sup 0/ Thomson scattering of 110-GHz, cw gyrotron radiation is proposed. Currently measured steady-state plasma parameters are: n/sub e/ = 1.5 x 10/sup 12/ cm/sup -3/, T/sub e/ = 500 eV, and T/sub i/ = 100 eV, with f/sub ce/ = 28 GHz. The measured plasma background at 100 GHz due to synchrotron emission from the relativistic electron rings is 10/sup 3/ times stronger than the expected scattered signal for an input power level to the plasma P/sub i/ = 10 kW. Therefore, gyrotron output modulation and synchronous detection are required. The collectively scattered spectra will be observed with a heterodyne detection system containing eight i.f. channels; each channel consists of a filter, a video detector, and a lock-in amplifier (which synchronously detects the modulated scattered signal). Scattering from low level suprathermal fluctuations and the applicability of the diagnostic to tokamaks are also considered.

  6. Magnetic field profile analysis for gyrotron experimental investigation

    NASA Astrophysics Data System (ADS)

    Pagonakis, Ioannis Gr.; Avramidis, Konstantinos A.; Gantenbein, Gerd; Rzesnicki, Tomasz; Samartsev, Andrey; Jelonnek, John

    2017-03-01

    The external applied magnetic field plays a main role on the gyrotron operation. Even if the gyrotron design is optimized for the nominal magnetic profile, it is possible the performance to be better for an alternative one. This unexpected result can happen for several reasons, such as the manufacturing imperfections, the misalignment issues, and several unknown factors in gyrotron theory and design. The systematic experimental investigation of the gyrotron in different magnetic profiles is very important for the optimization of the gyrotron operation and for the better understanding of the gyrotron behavior. In this sense, an analytical approach for the definition of the appropriate magnetic profiles based on the beam characteristics instead of the coil currents definition is proposed for a systematic experimental study. Using this technique, operational maps in the space of the important magnetic profile parameters are developed, which are very useful for the characterization of the gyrotron performance. For the demonstration of this idea, the operational maps of the short-pulse prototype of the 170 GHz, 1 MW European ITER gyrotron project are presented.

  7. Studies of novel 140 GHz gyrotrons

    NASA Astrophysics Data System (ADS)

    Hu, Wen

    We have designed, built and tested the world's first mode-selective confocal cavity gyrotron oscillator operating at 140GHz with over 66kW of RF power and up to 23% efficiency. The tube operates at the HE06 mode of the confocal cavity. A Magnetotron Injection Gun (MIG) provides an annular electron beam with up to 70kV and 8A. The confocal gyrotron oscillator is designed to better characterize the confocal cavity's mode spectrum for future amplifier applications. The device utilizes the interaction between an electron beam in cyclotron motion and the cavity mode in an open two-mirror confocal cavity are suppressed, and only gaussian-like modes can propagate with small loss. As a result, the confocal geometry reduces mode indices from two dimensional TEn,m to one dimensional HE0,q in confocal waveguide. The greatly reduced mode density of this structure lowers the risk of spurious mode competition, which is a critical issue in gyrotron development. Several models were formulated for various configurations of gyrotrons. A nonlinear theory for the mirror based quasi-optical Gyrotron Traveling Wave Tube (Gyro-TWT) was developed for the first time. The Gyro-TWT consists of a series of parallel spherical mirrors. A free space Gaussian beam propagates through the structure by bouncing between the mirrors in a serpentine path. A co- propagating electron beam in gyromotion interacts with and the amplifies the wave. The model shows excellent agreement with the well benchmarked linear theory. The phase front distortion effect in the quasi-optical gyro- TWT is revealed by this model. A preliminary confocal waveguide based gyro-TWT amplifier is designed. Cold tests of the quasi-optical input circuit show good gaussian beam transport with low loss. The amplifier performance is theoretically predicted to have a 4dB/cm linear gain, 20% efficiency and 70kW RF power. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)

  8. 1 megawatt, 100 GHz gyrotron study. Final report, March 21-September 1, 1983

    SciTech Connect

    Dionne, N.J.; Mallavarpu, R.; Palevsky, A.

    1983-11-21

    This report provides the results of a design study on a gyrotron device employing a new type of hollow gyrobeam formation system and having a capability for delivering megawatt CW power at 100 GHz to an ECRH-heated, magnetically-confined plasma. The conceptual basis for the beam formation system is the tilt-angle gun (TAG) in which a conically-shaped electron beam is formed in a magnetically-shielded region and is then injected into the stray-field region of the main magnetic focusing system. Because fluid coolants can be accessed through the central pole of the TAG-type gun, rf interaction can be contemplated with cavity configurations not practical with the conventional MIG-type gyrobeam formation systems.

  9. 60 GHz gyrotron development program. Final report, April 1979-June 1984

    SciTech Connect

    Shively, J.F.; Bier, R.E.; Caplan, M.; Cheng, M.K.; Choi, E.; Conner, C.C.; Craig, L.J.; Evans, S.J.; Evers, S.J.; Felch, K.L.

    1986-01-01

    The original objective of this program was to develop a microwave amplifier or oscillator capable of producing 200 kW CW power output at 110 GHz. The use of cyclotron resonance interaction was pursued, and the design phases of this effort are discussed. Later, however, the program's objective was changed to develop a family of oscillators capable of producing 200 kw of peak output power at 60 GHz. Gyrotron behavior studies were performed at 28 GHz to obtain generic design information as quickly as possible. The first experimental device at 60 GHz produced over 200 kw of peak power at a pulse duration of 20 ..mu..s. Heating problems and mode interference were encountered. The second experimental tube incorporated an optimized gun location but also suffered from mode interference. The third experimental tube included modifications that reduced mode interference. It demonstrated 200 kw of peak output at 100 ms pulse duration. The fourth experimental tube, which used an older rf circuit design but in a CW configuration, produced 71.5 kW CW. The fifth experimental tube incorporated a thinner double-disc output window which improved window bandwidth and reduced window loss. This tube also incorporated modifications to the drift tunnel and cavity coupling, which had proven successful in the third experimental pulse tube tests. It produced 123 kW of CW output power at 60 GHz rf load coolant boiling and tube window failure terminated the tests. A new waterload was designed and constructed, and alternative window designs were explored. A secondary task of developing a 56 GHz CW tube produced in excess of 100 kW CW at this alternate frequency. Testing of the sixth experimental tube resulted in operation at CW output power in the range of 200 to 206 kW for an hour. Output mode purity of the seventh experimental tube was measured at 95% TE/sub 02/. The tube was operated for about forty-five minutes with CW power output over 200 kW.

  10. CW bismuth fibre laser

    SciTech Connect

    Dianov, Evgenii M; Dvoyrin, V V; Mashinsky, V M; Umnikov, A A; Yashkov, M V; Gur'yanov, A N

    2005-12-31

    A new fibre laser based on a bismuth-doped aluminosilicate glass fibre is proposed and fabricated. CW lasing is obtained in the spectral region between 1150 and 1300 nm. The fibres are fabricated by the method of modified chemical vapour deposition. (letters)

  11. 95 GHz gyrotron with ferroelectric cathode.

    PubMed

    Einat, M; Pilossof, M; Ben-Moshe, R; Hirshbein, H; Borodin, D

    2012-11-02

    Ferroelectric cathodes were reported as a feasible electron source for microwave tubes. However, due to the surface plasma emission characterizing this cathode, operation of millimeter wave tubes based on it remains questionable. Nevertheless, the interest in compact high power sources of millimeter waves and specifically 95 GHz is continually growing. In this experiment, a ferroelectric cathode is used as an electron source for a gyrotron with the output frequency extended up to 95 GHz. Power above a 5 kW peak and ~0.5 μs pulses are reported; a duty cycle of 10% is estimated to be achievable.

  12. Design of Matching Optics Unit (MOU) for coaxial ITER gyrotron

    SciTech Connect

    Jin, Jianbo; Gantenbein, Gerd; Kern, Stefan; Rzesnicki, Tomasz; Thumm, Manfred

    2011-07-01

    The paper presents the design of a MOU for the coaxial ITER gyrotron. Corrugated waveguides are used to transmit the high power mm-waves generated by gyrotrons to the plasma Electron Cyclotron Resonance Heating (ECRH) and Current Drive (CD). The MOU contains two focusing mirrors, which are used to convert the gyrotron output into a Gaussian distribution with optimal parameters to improve the coupling efficiency of the TEM{sub 00} Gaussian distribution to the HE{sub 11} mode of the corrugated wave guide. The calculation results reveal that the coupling efficiency of the Gaussian beam to the HE{sub 11} mode is approximately 96.33%. (author)

  13. 110 GHz, 1 MW Gyrotron Design Upgrades

    NASA Astrophysics Data System (ADS)

    Cauffman, Steve; Felch, Kevin; Borchard, Philipp; Cahalan, Pat; Chu, Sam; Dubrule, Craig

    1999-11-01

    Communications and Power Industries has incorporated a number of design changes into its most recent series of 110 GHz 1 MW gyrotrons, for use in ECH and ECCD experiments on the DIII-D tokamak. Two development gyrotrons previously installed at DIII-D used a modulating-anode electron gun design and output windows consisting of double-disk face-cooled sapphire on one system and an edge-cooled CVD diamond disk on the other. Three new systems presently in fabrication and test employ (a) a single-anode electron gun to avoid excitation of spurious modes during turn-on and turn-off and to simplify power supply requirements, (b) a modified TE_22,6 cavity to reduce competition from neighboring modes, (c) a two inch aperture edge-cooled CVD diamond window to allow transmission of a 1 MW Gaussian output beam, (d) a superconducting magnet system with a cryo-cooler to reduce liquid helium consumption, and (e) a number of internal and external plumbing simplifications to make cooling system connections more straightforward. Initial test results, if available, will be presented.

  14. Reflections in gyrotrons with radial output: Consequences for the ITER coaxial gyrotron

    SciTech Connect

    Dumbrajs, O.; Nusinovich, G.S.; Piosczyk, B.

    2004-12-01

    A theory describing the influence of reflections on operation of gyrotrons with radial output is presented. The theory is used for evaluating the effect of reflections on the operation of the 170 GHz ITER coaxial cavity gyrotron, which is under development in cooperation between EUROATOM Associations (CRPP Lausanne, FZK Karlsruhe, and HUT Helsinki) together with European tube industry (Thales Electron Devices, Velizy, France). It is shown that for optimally chosen external magnetic field value and electron beam radius, possible reflections do not change the final steady-state operation, which corresponds to generation of a 2.2 MW millimeter-wave power. The effect of deviation of the magnetic field and the beam radius from optimal values on the device operation is also studied.

  15. Effect of electron beam misalignments on the gyrotron efficiency

    SciTech Connect

    Dumbrajs, O.; Nusinovich, G. S.

    2013-07-15

    The theory describing the operation of gyrotrons with tilted and shifted electron beams has been developed. Effects of the tilt and shift are studied for a 1 MW, 170 GHz gyrotron, which is presently under development in Europe for electron cyclotron resonance plasma heating and current drive in the International Thermonuclear Experimental Reactor. It is shown that one should expect significant deterioration of gyrotron operation in such gyrotrons when the tilt angle exceeds 0.4°–0.5° and the parallel shift of the beam axis with respect to the axis of a microwave circuit is larger than 0.4–0.5 mm. At the same time, simultaneous tilting and shifting in a proper manner can mitigate this deteriorating effect.

  16. The Multiple Gyrotron System on the DIII-D Tokamak

    DOE PAGES

    Lohr, J.; Anderson, J.; Brambila, R.; ...

    2015-08-28

    A major component of the versatile heating systems on the DIII-D tokamak is the gyrotron complex. This system routinely operates at 110 GHz with 4.7 MW generated rf power for electron cyclotron heating and current drive. The complex is being upgraded with the addition of new depressed collector potential gyrotrons operating at 117.5 GHz and generating rf power in excess of 1.0 MW each. The long term upgrade plan calls for 10 gyrotrons at the higher frequency being phased in as resources permit, for an injected power near 10 MW. This article presents a summary of the current status ofmore » the DIII-D gyrotron complex, its performance, individual components, testing procedures, operational parameters, plans, and a brief summary of the experiments for which the system is currently being used.« less

  17. The Multiple Gyrotron System on the DIII-D Tokamak

    SciTech Connect

    Lohr, J.; Anderson, J.; Brambila, R.; Cengher, M.; Chen, X.; Ellis, R. A.; Grosnickle, W.; Moeller, C.; Prater, R.; Ponce, D.; Riford, L.; Torrezan, A. C.

    2015-08-28

    A major component of the versatile heating systems on the DIII-D tokamak is the gyrotron complex. This system routinely operates at 110 GHz with 4.7 MW generated rf power for electron cyclotron heating and current drive. The complex is being upgraded with the addition of new depressed collector potential gyrotrons operating at 117.5 GHz and generating rf power in excess of 1.0 MW each. The long term upgrade plan calls for 10 gyrotrons at the higher frequency being phased in as resources permit, for an injected power near 10 MW. This article presents a summary of the current status of the DIII-D gyrotron complex, its performance, individual components, testing procedures, operational parameters, plans, and a brief summary of the experiments for which the system is currently being used.

  18. Harmonic gyrotrons operating in high-order symmetric modes

    SciTech Connect

    Nusinovich, Gregory S.; Kashyn, Dmytro G.; Antonsen, T. M.

    2015-01-05

    It is shown that gyrotrons operating at cyclotron harmonics can be designed for operation in symmetric TE{sub 0,p}-modes. Such operation in fundamental harmonic gyrotrons is possible only at small radial indices (p≤3) because of the severe mode competition with TE{sub 2,p}-modes, which are equally coupled to annular beams as the symmetric modes. At cyclotron harmonics, however, this “degeneracy” of coupling is absent, and there is a region in the parameter space where harmonic gyrotrons can steadily operate in symmetric modes. This fact is especially important for sub-THz and THz-range gyrotrons where ohmic losses limit the power achievable in continuous-wave and high duty cycle regimes.

  19. The Multiple Gyrotron System on the DIII-D Tokamak

    NASA Astrophysics Data System (ADS)

    Lohr, J.; Anderson, J.; Brambila, R.; Cengher, M.; Chen, X.; Ellis, R. A.; Grosnickle, W.; Moeller, C.; Prater, R.; Ponce, D.; Riford, L.; Torrezan, A. C.

    2016-01-01

    A major component of the versatile heating systems on the DIII-D tokamak is the gyrotron complex. This system routinely operates at 110 GHz with 4.7 MW-generated rf power for electron cyclotron heating and current drive. The complex is being upgraded with the addition of new depressed collector potential gyrotrons operating at 117.5 GHz and generating rf power in excess of 1.0 MW each. The long-term upgrade plan calls for 10 gyrotrons at the higher frequency being phased in as resources permit, for an injected power near 10 MW. This paper presents a summary of the current status of the DIII-D gyrotron complex, its performance, individual components, testing procedures, operational parameters, plans, and a brief summary of the experiments for which the system is currently being used.

  20. Intense high-frequency gyrotron-based microwave beams for material processing

    SciTech Connect

    Hardek, T.W.; Cooke, W.D.; Katz, J.D.; Perry, W.L.; Rees, D.E.

    1997-03-01

    Microwave processing of materials has traditionally utilized frequencies in the 0.915 and 2.45 GHz regions. Microwave power sources are readily available at these frequencies but the relatively long wavelengths can present challenges in uniformly heating materials. An additional difficulty is the poor coupling of ceramic based materials to the microwave energy. Los Alamos National Laboratory scientists, working in conjunction with the National Center for Manufacturing Sciences (NCMS), have assembled a high-frequency demonstration processing facility utilizing gyrotron based RF sources. The facility is primarily intended to demonstrate the unique features available at frequencies as high as 84 GHz. The authors can readily provide quasi-optical, 37 GHz beams at continuous wave (CW) power levels in the 10 kW range. They have also provided beams at 84 GHz at 10 kW CW power levels. They are presently preparing a facility to demonstrate the sintering of ceramics at 30 GHz. This paper presents an overview of the present demonstration processing facility and describes some of the features they have available now and will have available in the near future.

  1. The coaxial gyrotron with two electron beams. I. Linear theory and nonlinear theory

    SciTech Connect

    Liu Shenggang; Yuan Xuesong; Fu Wengjie; Yan Yang; Zhang Yaxin; Li Hongfu; Zhong Renbin

    2007-10-15

    The coaxial gyrotron with two electron beams (CGTB) is proposed and investigated in this paper. This paper consists of two parts: the linear theory and nonlinear theory of CGTB are presented in part I and the investigation on the dual frequency operation, a special operation state of CGTB, is given in part II. The magnetron injection gun with two electron beams has been developed, and simulations show that it may work well. It may guarantee that both the electric potential and the ratio of vertical to longitudinal velocities of two electron beams are equal. The results of the calculation show that CGTB has some distinguished advantages: mode competition is improved and output power is enhanced. Thus CGTB may be capable of providing 2-4 MW continuous-wave (CW) at 170 GHz to meet the demand of very high radio frequency CW power 1-2 MW in the ITER [ITER EDA Agreement and Protocol 2 (IAEA, Vienna, 1994)] program and other applications.

  2. Proposal of Mode Selection Criterian for Advanced KDEMO Gyrotron

    NASA Astrophysics Data System (ADS)

    Sawant, Ashwini; Choe, Mun Seok; Choi, EunMi

    2017-07-01

    We proposed the design of a 255 GHz advanced gyrotron for Korea demonstration power plant (KDEMO) operation. Mode selection criterian for this DEMO gyrotron (output power > 1 MW) is discussed and a conventional cavity is designed for selected TE55,13 mode. The designed cavity also excites the TE37,9 mode at 170 GHz frequency. Beam wave interaction at both the frequencies are also analysed in our study.

  3. Spectral Characteristics of a 140-GHz Long-Pulsed Gyrotron

    PubMed Central

    Han, Seong-Tae; Griffin, Robert G.; Hu, Kan-Nian; Joo, Chan-Gyu; Joye, Colin D.; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Torrezan, Antonio C.; Woskov, Paul P.

    2008-01-01

    Gyrotrons operating in the millimeter and submillimeter wavelength ranges are the promising sources for applications that are requiring good spectral characteristics and a wide range of output power. We report the precise measurement results of gyrotron spectra. Experiments were conducted using a 140-GHz long-pulse gyrotron that is developed for the dynamic nuclear polarization/nuclear-magnetic-resonance spectroscopy at the Massachusetts Institute of Technology. Transient downshift of the frequency by 12 MHz with a time constant of 3 s was observed. After reaching equilibrium, the frequency was maintained within 1 ppm for over 20 s. The coefficient of the frequency change with cavity temperature was −2.0 MHz/K, which shows that fine tuning of the gyrotron frequency is plausible by cavity-temperature control. Frequency pulling by the beam current was observed, but it was shown to be masked by the downward shift of the gyrotron frequency with temperature. The linewidth was measured to be much less than 1 MHz at 60 dB relative to the carrier power [in decibels relative to carrier (dBc)] and 4.3 MHz at 75 dBc, which is the largest dynamic range to date for the measurement of gyrotron linewidth to our knowledge. PMID:19081779

  4. Systematic Observation of Time-Dependent Phenomena in the RF Output Spectrum of High Power Gyrotrons

    NASA Astrophysics Data System (ADS)

    Schlaich, Andreas; Gantenbein, Gerd; Kern, Stefan; Thumm, Manfred

    2012-09-01

    At IHM/KIT, high power gyrotrons with conventional cavity (e.g. 1 MW CW at 140 GHz for the stellarator Wendelstein 7-X) and coaxial cavity (2 MW shortpulse at 170 GHz for ITER) for fusion applications are being developed and verified experimentally. Especially with respect to the problem of parasitic RF oscillations in the beam tunnel of some W7-X tubes, investigations of the gyrotron RF output spectrum have proved to be a valuable source of diagnostic information. Signs of transient effects in millisecond pulses, like frequency switching or intermittent low-frequency modulation, have indicated that truly time-dependent measurements with high frequency resolution and dynamic range could give deeper insight into these phenomena. In this paper, an improved measurement system is presented, which employs a fast oscilloscope as receiver. Shorttime Fourier transform (STFT) is applied to the time-domain signal, yielding time-variant spectra with frequency resolutions only limited by acquisition length and STFT segmentation choice. Typical reasonable resolutions are in the range of 100 kHz to 10 MHz with a currently memory-limited maximum acquisition length of 4 ms. A key feature of the system consists in the unambiguity of frequency measurement: The system receives through two parallel channels, each using a harmonic mixer (h = 9 - 12) to convert the signal from RF millimeter wave frequencies (full D-Band, 110 - 170 GHz) to IF (0 - 3 GHz). For each IF output signal of each individual mixer, injection side and receiving harmonic are initially not known. Using accordingly determined LO frequencies, this information is retrieved from the redundancy of the channels, yielding unambiguously reconstructed RF spectra with a total span of twice the usable receiver IF bandwidth, up to ≈ 6 GHz in our case. Using the system, which is still being improved continuously, various transient effects like cavity mode switching, parasitic oscillation frequency variation, and lowfrequency

  5. Experimental study of a 200--300 GHz megawatt gyrotron oscillator

    SciTech Connect

    Grimm, T.L.

    1992-01-01

    An experimental study is presented of a pulsed megawatt gyrotron oscillator operating in the 200-300 GHz range whose design is consistent with continuous operation for ECRH of fusion plasmas. A cylindrical waveguide cavity over 20 free space wavelengths in diameter was designed to limit ohmic wall losses in the copper cavity to < 2 kW/cm[sup 2]. The frequency spacing between TE waveguide modes in this highly overmoded cavity is < 2%. The cavity is positioned at the peak magnetic field of a 14 T Bitter magnet. Two different radii beams produced by magnetron injection guns (MIGs) were used to excite the cavity. The large and small MIG guns produced annual beams of 0.75 cm and 0.45 cm radius. The guns operate with beam currents approaching 60 A and voltages as high as 100 kV. The voltage is produced by a line-type modulator with a pulse length of 3 [mu]s at a repetition rate of up to 4 Hz. Megawatt power levels can be generated in CW gyrotron oscillators at 200-300 GHz with efficiencies approaching 20%. The emission is single mode, single frequency with a single rotation which can easily be mode converted for transmission. No multimoding was observed at the high powers and efficiencies. The highest power reached with the large MIG gun was 0.97 MW at 230 GHz in the TE[sub 34,6] mode with an efficiency of 18% and beam parameters of 59 A and 90kV. This was the peak efficiency which was also obtained at 290 GHz in the TE[sub 41,8] mode with a power of 0.89 MW and beam parameters of 54 A and 93 kV. The highest power with the small MIG gun was 0.78 MW at 280 GHz in the TE[sub 25,13] mode with an efficiency of 17% and beam parameters of 51 A and 92 kV. The small MIG gun peak efficiency was 18% at 0.72 MW, 290 GHz in the TE[sub 25,14] mode. Efficiencies are about half of less highly overmoded gyrotrons. Mode competition is the main cause of the low efficiency, with voltage depression, beam thickness and velocity spread contributing only a fraction to the decrease.

  6. Design of a Second Harmonic Double-Beam Continuous Wave Gyrotron with Operating Frequency of 0.79 THz

    NASA Astrophysics Data System (ADS)

    Manuilov, V. N.; Glyavin, M. Yu; Sedov, A. S.; Zaslavsky, V. Yu; Idehara, T.

    2015-12-01

    This paper presents the most essential steps of a design study of a novel second harmonic gyrotron operating in CW (continuous wave) regime at a frequency of 0.79 THz and an output power of 1-100 W. It is based on a novel idea for suppression of the parasitic modes using a double-beam electron-optical system (EOS). It includes a triode magnetron injection gun (MIG), which forms two high-quality helical electron beams (HEB). Different schemes, namely one with two generating beams and another with one generating and one absorbing beam, have been investigated and compared. It has been shown that the scheme with two generating beams is more advantageous since it allows an effective suppression of the parasitic modes and a stable single-mode operation at the second harmonic resonance. A MIG which is appropriate for the realization of the latter scheme has been optimized using numerical codes for computer-aided design (CAD). It forms beams with practically equal pitch factors and moderate velocity spread. The construction of the gun is not sensitive to small misalignments and shifts of the electrodes and the magnetic field. Among the most promising characteristics of the presented design are an improved mode selection and a stable single-mode generation at currents that are two to three times higher than the currents in the single-beam (i.e., conventional) gyrotrons.

  7. Structural and Microwave Properties of Silica Xerogel Glass-Ceramic Sintered by Sub-millimeter Wave Heating using a Gyrotron

    NASA Astrophysics Data System (ADS)

    Aripin, H.; Mitsudo, S.; Prima, E. S.; Sudiana, I. N.; Tani, S.; Sako, K.; Fujii, Y.; Saito, T.; Idehara, T.; Sano, S.; Sunendar, B.; Sabchevski, S.

    2012-11-01

    In this paper, we present and discuss experimental results from a microwave sintering of silica glass-ceramics, produced from amorphous silica xerogel extracted from sago waste ash. As a radiation source for a microwave heating a sub-millimeter wave gyrotron (Gyrotron FU CW I) with an output frequency of 300 GHz has been used. The powders of the amorphous silica xerogel have been dry pressed and then sintered at temperatures ranging from 300 °C to 1200 °C. Microwave absorbing properties of the sintered samples were investigated by measuring the dielectric constant, the dielectric loss, and the reflection loss at different frequencies in the interval from 8.2 to 12.4 GHz. Furthermore, the characteristics of the formation process for producing silica glass-ceramics were studied using a Raman Spectroscopy and a Scanning Electron Microscopy (SEM). The results indicate that the samples sintered at 1200 °C are characterized by lower reflection losses and a better transparency due to the formation of a fully crystallized silica glass- ceramic at sufficiently high temperature.

  8. Gyrotron and its Electron Beam Source: A Review

    NASA Astrophysics Data System (ADS)

    Singh, Udaybir; Kumar, Nitin; Sinha, AK

    2012-10-01

    Microwave occupies a glorious position in the electromagnetic spectrum and in that there are a number of devices in this frequency regime which are capable of high power operations. Among them, gyrotron has proven to be an efficient source for radio frequency (RF) generation at high power level and up to very high frequency. The gyrotron consists of several components like electron beam source, interaction structure, quasi-optical launcher, collector, RF window, magnet system, etc. All the components have their distinct role in the function of the device. Among them, electron beam source also called magnetron injection gun (MIG) is the generator of electron beam and it is very essential that MIG should produce and provide electron beam suitable for the beam-wave interaction at the interaction structure for the effective power growth. The paper presents the introduction of a microwave tube, gyrotron and its components alongwith review of the previous work, the background and the applications. The functions of various components of a gyrotron are discussed with particular highlighting on the electron beam emission from the electron beam source and the beam-wave interaction for power growth in the device. A review on different types of gyrotron electron beam sources is also presented.

  9. High-Speed Frequency Modulation of a 460-GHz Gyrotron for Enhancement of 700-MHz DNP-NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Idehara, T.; Khutoryan, E. M.; Tatematsu, Y.; Yamaguchi, Y.; Kuleshov, A. N.; Dumbrajs, O.; Matsuki, Y.; Fujiwara, T.

    2015-09-01

    The high-speed frequency modulation of a 460-GHz Gyrotron FU CW GVI (the official name in Osaka University is Gyrotron FU CW GOI) was achieved by modulation of acceleration voltage of beam electrons. The modulation speed f m can be increased up to 10 kHz without decreasing the modulation amplitude δ f of frequency. The amplitude δ f was increased almost linearly with the modulation amplitude of acceleration voltage Δ V a. At the Δ V a = 1 kV, frequency spectrum width df was 50 MHz in the case of f m < 10 kHz. The frequency modulation was observed as both the variation of the IF frequency in the heterodyne detection system measured by a high-speed oscilloscope and the widths of frequency spectra df measured on a frequency spectrum analyzer. Both results well agree reasonably. When f m exceeds 10 kHz, the amplitude δ f is decreased gradually with increasing f m because of the degradation of the used amplifier in response for high-speed modulation. The experiment was performed successfully for both a sinusoidal wave and triangle wave modulations. We can use the high-speed frequency modulation for increasing the enhancement factor of the dynamic nuclear polarization (DNP)-enhanced nuclear magnetic resonance (NMR) spectroscopy, which is one of effective and attractive methods for the high-frequency DNP-NMR spectroscopy, for example, at 700 MHz. Because the sensitivity of NMR is inversely proportional to the frequency, high-speed frequency modulation can compensate the decreasing the enhancement factor in the high-frequency DNP-NMR spectroscopy and keep the factor at high value. In addition, the high-speed frequency modulation is useful for frequency stabilization by a PID control of an acceleration voltage by feeding back of the fluctuation of frequency. The frequency stabilization in long time is also useful for application of a DNP-NMR spectroscopy to the analysis of complicated protein molecules.

  10. Design and development of mode launcher for high frequency Gyrotron

    NASA Astrophysics Data System (ADS)

    Alaria, Mukesh Kumar; Sinha, A. K.; Khatun, H.

    2016-03-01

    In this paper, we describe the design and development of helical cut smooth wall mode launcher for high frequency and high power Gyrotron. A Vlasov-type helical cut mode launcher for converting TE22,6 mode to a Gaussian mode has been designed for 120 GHz, 1 MW Gyrotron. The initial design of mode launcher has been optimized using LOT/SURF-3D software. The mode launcher diameter and length are optimized considering the minimum return loss and the minimum insertion loss by using CST microwave studio. The return loss (S11) and insertion loss (S21) performance of helical cut smooth wall mode launcher have been obtained using CST-Microwave Studio. The fabrication of Vlasov-type helical cut mode launcher for 120 GHz Gyrotron has also been carried out.

  11. Multimode time-dependent gyrotron equations for different time scales

    NASA Astrophysics Data System (ADS)

    Dumbrajs, O.; Kalis, H.

    2017-09-01

    Development of gyrotrons requires careful understanding of different regimes of gyrotron oscillations. For a long time, the gyrotron theory was developed assuming that the transit time of electrons through the interaction space is much shorter than the cavity fill time. Correspondingly, it was assumed that during this transit time, the amplitude of microwave oscillations remains constant. However, there are situations when this assumption is not fulfilled, or is marginally fulfilled. In such cases, a different mathematical formalism has to be used. The present paper generalizes the new formalism to the multi mode case. The particular example considered indicates that in some cases the results obtained by means of the old and the new formalism differ significantly.

  12. Development of high-power gyrotrons with gradually tapered cavity

    SciTech Connect

    Lei Chaojun; Yu Sheng; Niu Xinjian; Liu Yinghui; Li Hongfu; Li Xiang

    2012-12-15

    In high power gyrotrons, the parasitic modes coupled with the operating mode cannot be avoided in the beam-wave interaction. These parasitic modes will decrease the efficiency of the gyrotrons. The purity of the operating mode affected by different tapers should be carefully studied. The steady-state self-consistent nonlinear theory for gyrotron with gradually tapered cavity is developed in this paper. A steady-state calculation code including 'cold cavity' and 'hot cavity' is designed. By comparison, a time-domain model analysis of gyrotron operation is also studied by particle-in-cell (PIC). It is found that the tapers of gyrotron have different influences on the modes coupling between the operating mode and the parasitic modes. During the study, an example of 94 GHz gyrotron with pure operating mode TE{sub 03} has been designed. The purity of the operating mode in the optimized cavity is up to -77 dB, and in output waveguide of the cavity is up to -76 dB. At the same time, the beam-wave interaction in the designed cavity has been simulated, too. An output power of 120 kW, corresponding to 41.6% efficiency and an oscillation frequency of 94.099 GHz have been achieved with a 50 kV, 6 A helical electron beam at a guiding magnetic field of 3.5485 T. The results show that the power in spurious modes of the optimized cavity may be kept far below than that of the traditional tapered cavity.

  13. Suppression of parasitic space-charge oscillations in a gyrotron

    NASA Astrophysics Data System (ADS)

    Louksha, O. I.; Piosczyk, B.; Sominski, G. G.; Thumm, M.; Samsonov, D. B.

    2006-10-01

    We study the influence of nonuniform electric and magnetic fields in the helical-beam compression region on the low-frequency parasitic space-charge oscillations for a moderate-power (˜ 100 kW) 4-mm gyrotron. Suppression of the oscillations is achieved by optimization of both the cathode-unit geometry in the magnetron-injector gun and the magnetic-field distribution in the region near the cavity input. The obtained data are evidence of possible effective operation of the gyrotron at elevated pitch-factor values α > 1.5 even for emitters with no highest emission uniformity (δje ≈ 30%).

  14. Phonological and Phonetic Asymmetries of Cw Combinations

    ERIC Educational Resources Information Center

    Suh, Yunju

    2009-01-01

    This thesis investigates the relationship between the phonological distribution of Cw combinations, and the acoustic/perceptual distinctiveness between syllables with plain C onsets and with Cw combination onsets. Distributional asymmetries of Cw combinations discussed in this thesis include the avoidance of Cw combinations in the labial consonant…

  15. Phonological and Phonetic Asymmetries of Cw Combinations

    ERIC Educational Resources Information Center

    Suh, Yunju

    2009-01-01

    This thesis investigates the relationship between the phonological distribution of Cw combinations, and the acoustic/perceptual distinctiveness between syllables with plain C onsets and with Cw combination onsets. Distributional asymmetries of Cw combinations discussed in this thesis include the avoidance of Cw combinations in the labial consonant…

  16. A Gyrotron-Powered Pellet Accelerator

    NASA Astrophysics Data System (ADS)

    Perkins, F. W.; Parks, P. B.

    2005-10-01

    Plans for fuelling ITER call for accelerated pellets which propagate in guide-tubes. The tubes undergo 90 bends so that the pellets can enter the plasma along the high field-side of the separatrix. Both theory and experiment find that for V>= 500m/s, centrifugal force in the bends will fracture the pellets and elongate the cloud of debris. This contribution outlines the design of a plasma accelerator sufficiently flexible so that 90 bends can be avoided for the high-speed portions of the trajectory. The key element is to recognize that the guide tubes can also serve as a waveguide for millimeter waves. Operation proceeds as follows: A pellet is introduced into a guide tube of diameter 5mm at low velocity ˜10m/s and propagates until the remaining trajectory is straight and normal to separatrix. At this point, a 1 MW gyrotron is energized and power propagates until it encounters the pellet. The pellet has a 4-region structure and acts as a gun. The rear region (5mm) is diamond which passes the millimeter waves and provides inertia. Next is a 2mm region of frozen D doped with lithium which adsorbs the millimeter waves and vaporizes. The third region is a thin lithium layer which is several skin depths in extent and reflects millimeter waves. The 5 mm front region is a frozen DT bullet accelerated by the vaporized absorbing layer. The bullet now has a straight trajectory. 1D simulations of the gun will be presented.

  17. The DIII-D ECH multiple gyrotron control system

    SciTech Connect

    Ponce, D.; Lohr, J.; Tooker, J.F.; Cary, W.P.; Harris, T.E.

    1997-11-01

    DIII-D`s ECH upgrade with 1 MW, 110 GHz gyrotrons is ongoing, and with it, an upgrade of the control system. The ECH Multiple Gyrotron Control System uses software distributed among networked computers, interfaced to a programmable logic controller (PLC), the timing and pulse system, power supplies, vacuum and wave guide controls, and instrumentation. During DIII-D operations, the system will allow a chief and a co-operator to control and monitor a number of gyrotrons from different manufacturers. The software, written using LabVIEW, allows for remote and multiple operator control. Thus any supported computer can become a control station and multiple projects can be simultaneously accommodated. Each operator can be given access to the controls of all gyrotrons or to a subset of controls. Status information is also remotely available. The use of a PLC simplifies the hardware and software design. It reduces interlock and control circuitry, includes monitoring for slow analog signals, and allows one software driver to efficiently interface to a number of systems. In addition, the interlock logic can be easily changed and control points can be forced as needed. The pulse system is designed around arbitrary function generators. Various modulation schemes can be accommodated, including real-time control of the modulation. This discussion will include the hardware and software design of the control system and its current implementation.

  18. Study of Cavity and Output Window for High Power Gyrotron

    NASA Astrophysics Data System (ADS)

    Alaria, M. K.; Mukherjee, P.; Das, S.; Sinha, A. K.

    2011-02-01

    In this paper Eigen mode analysis has been carried out using Ansoft HFSS for high frequency 42, 120 and 140 GHz Gyrotron cavity. The design of RF window for 42 GHz, 200 kW Gyrotron has also been carried out using the Ansoft HFSS and CST microwave studio. In 42 GHz gyrotron double disc of diameter 85 mm and thickness 3.2 mm sapphire window and spacing (Coolant FC-75) of discs 2.5 mm has been used in the simulation. The return loss (S11) and transmission loss (S21) of the 42 GHz gyrotron window have been found -47.3 and -0.04 dB, respectively. The return loss and transmission loss of the S-band single disc sapphire window have also been found -27.3 and -0.07 dB, respectively at cylindrical waveguide length 33 mm. The simulated result has been validated through experimental results for pill-box S-band sapphire window.

  19. High Voltage K sub a -Band Gyrotron Experiment.

    DTIC Science & Technology

    1985-11-20

    N.S. Ginzburg, V.I. Krementsov, M.I. Petelin , P.S. Strelkov, and A.K. Shkvarunets, "Experimental investigation of a high-current relativistic...15. V.L. Bratman, N.S. Ginzburg, G.S. Nusinovich, M.I. Petelin , and P.S. Strelkov, "Relativistic gyrotrons and cyclotron autoresonance masers

  20. System Development and Performance Testing of a W-Band Gyrotron

    NASA Astrophysics Data System (ADS)

    Kim, Sung Gug; Sawant, Ashwini; Lee, Ingeun; Kim, Dongsung; Choe, MunSeok; Won, Jong-Hyo; Kim, Jungho; So, Joonho; Jang, Won; Choi, EunMi

    2016-03-01

    A high-power W-band gyrotron has been designed and performance tested in Korea, with an output power in the range of tens of kilowatts. The gyrotron consists of a diode-type electron gun operating at 40 kV, a TE6,2 mode interaction cavity, and a mode converter for producing a highly Gaussian output mode beam. Presented here are the detailed component design procedure and the experimental results of the gyrotron's performance evaluation. A maximum power of 62 kW was achieved with an efficiency of 22 %, and a highly Gaussian output beam was observed. The gyrotron's output beam is analyzed, and its transmission through an oversized waveguide is discussed. This gyrotron is the first gyrotron developed in Korea with high power greater than 10 kW and high frequency greater than 90 GHz.

  1. Note: A 95 GHz mid-power gyrotron for medical applications measurements

    NASA Astrophysics Data System (ADS)

    Pilossof, Moritz; Einat, Moshe

    2015-01-01

    A mid-power 95 GHz gyrotron was built and used for measuring insertion loss of biological tissue. The gyrotron is a compact table-top device that allows convenient measurements in a biological setup. It operates at the fundamental harmonic with TE02 circular mode. A mode converter is used to obtain TE10 rectangular mode in standard WR10 components. Using this gyrotron, beef tissue insertion loss was measured to be about 7-8 dB per millimeter.

  2. Operating experience on six 110 GHz, 1 MW gyrotrons for ECH applications

    NASA Astrophysics Data System (ADS)

    Felch, K.; Blank, M.; Borchard, P.; Cahalan, P.; Cauffman, S.; Jory, H.; Gorelov, Y.; Lohr, J.

    2008-05-01

    Since 1999, CPI has shipped six, 110 GHz, 1 MW, 5 s pulsed gyrotrons to General Atomics (GA) for use in electron cyclotron heating experiments on the DIII-D tokamak. As a result of extensive testing of these gyrotrons at CPI and GA, a wealth of information has been obtained regarding the long-term performance of the original electrical and mechanical design of the tubes. All of the gyrotrons have achieved long-pulse operation and five of the six gyrotrons achieved 1 MW output power levels with the nominal beam voltage and current of 80 kV and 40 A, respectively. Experience with the electron guns and interaction cavities has been quite good, though the low efficiency experienced by one gyrotron may be attributed to a gun or cavity irregularity. The internal converters employed in the gyrotrons have produced high-quality Gaussian output beams with internal diffractions losses of 5-6.5%. After several years of operation, the first three 110 GHz gyrotrons experienced collector failures due to cyclic fatigue. Improved analyses and diagnostics have been employed to avoid these problems in the future. Two problems have been experienced with the diamond output windows. These problems have been eliminated by changing braze techniques and procedures. Based on the experience obtained on these six gyrotrons, recommendations can be made for future gyrotron development work.

  3. CW RFQ fabrication and engineering

    SciTech Connect

    Schrage, D.; Young, L.; Roybal, P.

    1998-12-31

    The design and fabrication of a four-vane RFQ to deliver a 100 mA CW proton beam at 6.7 MeV is described. This linac is an Oxygen-Free Electrolytic (OFE) copper structure 8 m in length and was fabricated using hydrogen furnace brazing as the joining technology.

  4. Optimal parameters of gyrotrons with weak electron-wave interaction

    NASA Astrophysics Data System (ADS)

    Glyavin, M. Yu.; Oparina, Yu. S.; Savilov, A. V.; Sedov, A. S.

    2016-09-01

    In low-power gyrotrons with weak electron-wave interaction, there is a problem of determining the optimal length of the operating cavity, which is found as a result of a tradeoff between the enhancement of the electron efficiency and the increase in the Ohmic loss share with increasing cavity length. In fact, this is the problem of an optimal ratio between the diffraction and Ohmic Q-factors of the operating gyrotron mode, which determines the share of the radiated rf power lost in the cavity wall. In this paper, this problem is studied on the basis of a universal set of equations, which are appropriate for a wide class of electron oscillators with low efficiencies of the electron-wave interaction.

  5. Loaded Q's and field profiles of tapered axisymmetric gyrotron cavities

    SciTech Connect

    Derfler, H.; Grant, T.J.; Stone, D.S.

    1982-12-01

    A theoretical investigation of the vacuum electromagnetic properties of a class of tapered cylindrical resonant cavities employed in gyrotron design is reported. The cavity properties which determine gyrotron interaction efficiency-field profiles and loaded Q's-are predicted as a function of the geometric parameters. The authors show that this resonator geometry is superior to other designs for several reasons: 1) its properties are less sensitive to machining tolerances; 2) it produces negligible mode conversion at the output; and 3) in contrast with the imitations of iris-coupled designs, is capable of providing loaded Q's as low as about 0.3 Q diff where Q diff=4..pi..(L/lambda)/sup 2/ is the ''diffraction limit.'' Cold tests in the millimeter bands are reported which verify these conclusions.

  6. Startup and mode competition in a 420 GHz gyrotron

    NASA Astrophysics Data System (ADS)

    Qixiang Zhao, A.; Sheng Yu, B.; Tianzhong Zhang, C.

    2017-09-01

    In the experiments of a 420 GHz second-harmonic gyrotron, it is found that the electron beam voltage and current ranges for single mode operation of TE17.4 are slightly narrower than those in the simulation. To explain this phenomenon, the startup scenario has been investigated with special emphasis on mode competition. The calculations indicate that the decreases of the operating ranges are caused by the voltage overshoot in the startup scenario.

  7. Self-consistent non-stationary theory of the gyrotron

    SciTech Connect

    Dumbrajs, Olgierd; Nusinovich, Gregory S.

    2016-08-15

    For a long time, the gyrotron theory was developed assuming that the transit time of electrons through the interaction space is much shorter than the cavity fill time. Correspondingly, it was assumed that during this transit time, the amplitude of microwave oscillations remains constant. A recent interest to such additional effects as the after-cavity interaction between electrons and the outgoing wave in the output waveguide had stimulated some studies of the beam-wave interaction processes over much longer distances than a regular part of the waveguide which serves as a cavity in gyrotrons. Correspondingly, it turned out that the gyrotron theory free from the assumption about constant amplitude of microwave oscillations during the electron transit time should be developed. The present paper contains some results obtained in the framework of such theory. The main attention is paid to modification of the boundary between the regions of oscillations with constant amplitude and automodulation in the plane of normalized parameters characterizing the external magnetic field and the beam current. It is shown that the theory free from the assumption about the frozen wave amplitude during the electron transit time predicts some widening of the region of automodulation.

  8. A 670 GHz gyrotron with record power and efficiency

    NASA Astrophysics Data System (ADS)

    Glyavin, M. Yu.; Luchinin, A. G.; Nusinovich, G. S.; Rodgers, J.; Kashyn, D. G.; Romero-Talamas, C. A.; Pu, R.

    2012-10-01

    A 670 GHz gyrotron with record power and efficiency has been developed in joint experiments of the Institute of Applied Physics, Russian Academy of Sciences (Nizhny Novgord, Russia), and the University of Maryland (USA) teams. The magnetic field of 27-28 T required for operation at the 670 GHz at the fundamental cyclotron resonance is produced by a pulsed solenoid. The pulse duration of the magnetic field is several milliseconds. A gyrotron is driven by a 70 kV, 15 A electron beam, so the beam power is on the order of 1 MW in 10-20 ms pulses. The ratio of the orbital to axial electron velocity components is in the range of 1.2-1.3. The gyrotron is designed to operate in the TE31,8-mode. Operation in a so high-order mode results in relatively low ohmic losses (less than 10% of the radiated power). Achieved power of the outgoing radiation (210 kW) and corresponding efficiency (about 20%) represent record numbers for high-power sources of sub-THz radiation.

  9. Self-consistent non-stationary theory of the gyrotron

    NASA Astrophysics Data System (ADS)

    Dumbrajs, Olgierd; Nusinovich, Gregory S.

    2016-08-01

    For a long time, the gyrotron theory was developed assuming that the transit time of electrons through the interaction space is much shorter than the cavity fill time. Correspondingly, it was assumed that during this transit time, the amplitude of microwave oscillations remains constant. A recent interest to such additional effects as the after-cavity interaction between electrons and the outgoing wave in the output waveguide had stimulated some studies of the beam-wave interaction processes over much longer distances than a regular part of the waveguide which serves as a cavity in gyrotrons. Correspondingly, it turned out that the gyrotron theory free from the assumption about constant amplitude of microwave oscillations during the electron transit time should be developed. The present paper contains some results obtained in the framework of such theory. The main attention is paid to modification of the boundary between the regions of oscillations with constant amplitude and automodulation in the plane of normalized parameters characterizing the external magnetic field and the beam current. It is shown that the theory free from the assumption about the frozen wave amplitude during the electron transit time predicts some widening of the region of automodulation.

  10. Investigations and advanced concepts on gyrotron interaction modeling and simulations

    SciTech Connect

    Avramidis, K. A.

    2015-12-15

    In gyrotron theory, the interaction between the electron beam and the high frequency electromagnetic field is commonly modeled using the slow variables approach. The slow variables are quantities that vary slowly in time in comparison to the electron cyclotron frequency. They represent the electron momentum and the high frequency field of the resonant TE modes in the gyrotron cavity. For their definition, some reference frequencies need to be introduced. These include the so-called averaging frequency, used to define the slow variable corresponding to the electron momentum, and the carrier frequencies, used to define the slow variables corresponding to the field envelopes of the modes. From the mathematical point of view, the choice of the reference frequencies is, to some extent, arbitrary. However, from the numerical point of view, there are arguments that point toward specific choices, in the sense that these choices are advantageous in terms of simulation speed and accuracy. In this paper, the typical monochromatic gyrotron operation is considered, and the numerical integration of the interaction equations is performed by the trajectory approach, since it is the fastest, and therefore it is the one that is most commonly used. The influence of the choice of the reference frequencies on the interaction simulations is studied using theoretical arguments, as well as numerical simulations. From these investigations, appropriate choices for the values of the reference frequencies are identified. In addition, novel, advanced concepts for the definitions of these frequencies are addressed, and their benefits are demonstrated numerically.

  11. CW laser pumped emerald laser

    SciTech Connect

    Shand, M.L.; Lai, S.T.

    1984-02-01

    A CW laser-pumped emerald laser is reported. A 34 percent output power slope efficiency is observed with longitudinal pumping by a krypton laser in a nearly concentric cavity. The laser has been tuned from 728.8 to 809.0 nm. Losses in emerald are larger than those of alexandrite determined in a similar cavity. The present data also indicate that the excited state absorption minimum is shifted from that of alexandrite. 13 references.

  12. Design study of a 0.4 THz 100 kW pulsed gyrotron

    SciTech Connect

    Choi, E.M.

    2011-07-01

    We present a status of development of a 0.4 THz, 100 kW pulsed gyrotron at UNIST 0.4 THz, 100 kW gyrotron is currently under design for a remote radioactive material detection. A magnetic injection gun (MIG) is used for the electron gun with a beam voltage of 70 kV and beam current of 10 A with a pulse duration of 10 usec. A second harmonic cavity for the gyrotron interaction is considered for the high power THz gyrotron. Numerical optimization of the electron gun design and the cavity is performed in the study. In this paper, we briefly report the design study of the gyrotron. (author)

  13. Power Accountability with 1 MW 110 GHz Gyrotron System on the DIII--D Tokamak

    NASA Astrophysics Data System (ADS)

    Zhang, Daqing; Lohr, John; Tooker, J. W.; Ponce, Dan; Callis, R. W.

    1996-11-01

    A new gyrotron system (110 GHz, 1 MW, 2 sec) has been built for the DIII--D tokamak. Before the ECH physics experiments were carried out on DIII--D, the power produced by the gyrotron was measured carefully as well as the power absorbed by parts of the system such as in the gyrotron window, mirror optics unit, miter bends, and dummy loads, for different pulse durations. The maximum output power achieved up to now is 885 kW for 500 msec pulse length. The gyrotron generation efficiency is 37%, very close to the optimum operation parameters, and the whole system's efficiency is 29%. The output mode and frequency of the gyrotron was also measured. Detailed experimental results will be presented.

  14. INFRARED MONITORING OF 110GHz GYROTRON WINDOWS AT DIII-D

    SciTech Connect

    Y. GORELOV; J. LOHR; R.W. CALLIS; D. PONCE

    2002-05-01

    The combination of low millimeter wave losses and excellent thermal conductivity with good mechanical properties make artificial chemical vapor deposition (CVD) diamonds a compelling choice for 1 MW 110 GHz gyrotron windows. Five gyrotrons are currently operating at the DIII-D tokamak. Three Gycom gyrotrons have boron nitride (BN) ceramic windows. Due to temperature increases of the windows up to about 930 C, the pulse duration of these tubes is limited to 2 s for output power near 800 kW. Two Communications and Power Industries (CPI) gyrotrons with diamond windows are also installed and operating. The diamond disks of these windows and the construction of their water-cooling assemblies are different. This paper reviews the infrared (IR) measurements of both types of gyrotron windows, with emphasis on the two diamond designs.

  15. Research on a 170 GHz, 2 MW coaxial cavity gyrotron with inner-outer corrugation

    SciTech Connect

    Hou, Shenyong; Yu, Sheng; Li, Hongfu

    2015-03-15

    In this paper, a coaxial cavity gyrotron with inner-outer corrugation is researched. The electron kineto-equations and the first order transmission line equations of the gyrotron are derived from Lorentz force equation and the transmission line theory, respectively. And then, a 2 MW, 170 GHz coaxial cavity gyrotron with inner-outer corrugation is designed. By means of numerical calculation, the beam-wave interaction of the coaxial cavity gyrotron with inner-outer corrugation is investigated. Results show that the efficient and the outpower of the gyrotron are 42.3% and 2.38 MW, respectively.

  16. CW simulant detection by NDIR

    NASA Astrophysics Data System (ADS)

    Daly, Jim; McNeal, Mark; Gully, Bill; Swanson, Frank

    2005-11-01

    A compact, low-cost, multi-wavelength NDIR sensor was designed to measure G-type CW agents at ppm-levels. This 4-color sensor can distinguish between the different agents (sarin, soman, tabun) and is more sensitive than a single wavelength sensor. The design of the sensor and test results with simulants R-12 (dichlorodifluoromethane) and sulfur hexafluoride is presented. These test results support a lower detection limit of 3 ppmv for a 1 sec integration time. Modifications of the sensor design which will enable us to achieve <1 ppmv sensitivity are discussed.

  17. High power 303 GHz gyrotron for CTS in LHD

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Y.; Kasa, J.; Saito, T.; Tatematsu, Y.; Kotera, M.; Kubo, S.; Shimozuma, T.; Tanaka, K.; Nishiura, M.

    2015-10-01

    A high-power pulsed gyrotron is under development for 300 GHz-band collective Thomson scattering (CTS) diagnostics in the Large Helical Device (LHD). High-density plasmas in the LHD require a probe wave with power exceeding 100 kW in the sub-terahertz region to obtain sufficient signal intensity and large scattering angles. At the same time, the frequency bandwidth should be less than several tens of megahertz to protect the CTS receiver using a notch filter against stray radiations. Moreover, duty cycles of ~ 10% are desired for the time domain analysis of the CTS spectrum. At present, a 77 GHz gyrotron for electron cyclotron heating is used as a CTS wave source in the LHD. However, the use of such a low-frequency wave suffers from refraction, cutoff and absorption at the electron cyclotron resonance layer. Additionally, the signal detection is severely affected by background noise from electron cyclotron emission. To resolve those problems, high-power gyrotrons in the 300 GHz range have been developed. In this frequency range, avoiding mode competition is critical to realizing high-power and stable oscillation. A moderately over-moded cavity was investigated to isolate a desired mode from neighbouring modes. After successful tests with a prototype tube, the practical one was constructed with a cavity for TE22,2 operation mode, a triode electron gun forming intense laminar electron beams, and an internal mode convertor. We have experimentally confirmed single mode oscillation of the TE22,2 mode at the frequency of 303.3 GHz. The spectrum peak is sufficiently narrow. The output power of 290 kW has been obtained at the moment.

  18. Transmission Line for 258 GHz Gyrotron DNP Spectrometry

    NASA Astrophysics Data System (ADS)

    Bogdashov, Alexandr A.; Belousov, Vladimir I.; Chirkov, Alexey V.; Denisov, Gregory G.; Korchagin, Vyacheslav V.; Kornishin, Sergey Yu.; Tai, Evgeny M.

    2011-06-01

    We describe the design and test results of the transmission line for liquid-state (LS) and solid-state (SS) DNP spectrometers with the second-harmonic 258.6 GHz gyrotron at the Institute of the Biophysical Chemistry Center of Goethe University (Frankfurt). The 13-meter line includes a mode converter, HE11 waveguides, 4 mitre bends, a variable polarizer-attenuator, directional couplers, a water-flow calorimeter and a mechanical switch. A microwave power of about 15 W was obtained in the pure HE11 mode at the spectrometer inputs.

  19. Operation Of A 140 GHz Tunable Backward Wave Gyrotron Oscillator

    NASA Astrophysics Data System (ADS)

    Guss, W. C.; Kreischer, K. E.; Temkin, R. J.; Caplan, M.; Pirkle, D.

    1988-11-01

    A tunable backward-wave oscillator (BWO) gyrotron is currently being operated at MIT which is a prototype for a FEL driver at high frequency. Novel features of this design, are the overmoded TE12 cylindrical cavity, a wide band moth-eye window, and the use of a Pierce-wiggler gun. The design objectives are voltage tuning from 130-140 GHz with 10 kW output power. The interaction region is 10λο long where λο is the free space wave length. A linear 2° uptaper is used to maintain mode purity and a broadband motheye window is used for maximum transmission.

  20. Computer simulation of phase locking multi-cavity relativistic gyrotrons

    NASA Astrophysics Data System (ADS)

    Lin, A. T.; Yang, Z. H.; Lin, Chih-Chien

    1989-07-01

    A particle-in-cell model has been employed to investigate the phase-locking phenomenon of multi-cavity relativistic gyrotron oscillators. Simulation results show that a prebunched beam causes the output wave to overshoot, which in turn prolongs the time for establishing phase locking. The beam axial velocity spread is observed to reduce the locking bandwidth. The phenomenon of priming or injection seeding is simulated. The phase locked time depends on the growth rate of the oscillator and the amount of inject frequency deviation from the locking boundary.

  1. CW ultrasonic bolt tensioning monitor

    NASA Technical Reports Server (NTRS)

    Heyman, J. S. (Inventor)

    1977-01-01

    A CW ultrasonic device is described for measuring frequency shifts of the peak of a mechanical resonance in a body. One application of the device is measuring the strain in a bolt, and other applications such as measuring the thickness of a body, measuring the depth of a flaw in a body, measuring the elongation of a body, and measuring changes in velocity of sound in a body. The body is connected, by means of a CW transducer, to electrical circuit means including a narrow band RF amplifier to form a closed loop feedback marginal oscillator that frequency locks the device to the peak of a mechanical resonance in the body. When the frequency of this peak changes, because of a physical change in the body, the frequency of the oscillator changes. The device includes an automatic frequency resonant peak tracker that produces a voltage that is related to a change in frequency of the oscillator. This voltage is applied to the RF amplifier to change the center of its frequency band to include the frequency of the peak and is a measure of the frequency shift.

  2. HIGH POWER LONG PULSE PERFORMANCE OF THE DIII-D GYROTRON INSTALLATION

    SciTech Connect

    J. LOHR; Y.A. GORELOV; R.W. CALLIS; H.J. GRUNLOH; J.J. PEAVY; R.I. PINSKER; D. PONCE; R. PRATER; R.A. ELLIS,III

    2002-05-01

    At DIII-D, five 110 GHz gyrotrons are operating routinely for 2.0 s pulses at generated power levels {ge}750 kW per gyrotron. A sixth gyrotron is being installed, which should bring the generated power level to >4 MW and the injected power to about 3.0 MW. The output power now can be modulated by the plasma control system to fix T{sub e} at a desired value. The system is being used as a tool for control of current diffusion, for current profile control and other experiments leading to advanced tokamak operation.

  3. Nonlinear theory for a terahertz gyrotron with a special cross-section interaction cavity

    SciTech Connect

    Yuan, Xuesong; Han Yu; Yan Yang; Lan Ying

    2012-05-15

    The fully numerical nonlinear theory for a gyrotron with a special cross-section interaction cavity has been developed in this paper. In this theory, the analytical solution to different modes in the special cross-section interaction cavity is replaced by the numerical solution based on electromagnetic simulation results. A 0.4 THz third harmonic gyrotron with an azimuthally corrugated interaction cavity has been investigated by using this theory and simulation results show that this approach has a significant advantage of developing high harmonic terahertz gyrotrons.

  4. A Gyrotron-Powered Pellet Accelerator for Tokamak Fueling

    NASA Astrophysics Data System (ADS)

    Parks, P. B.; Perkins, F. W.

    2006-04-01

    A novel pellet acceleration concept [1] using microwave power from MW gyrotron sources has been developed that could pave the way for high-speed >3 km/s inner-wall pellet injection on ITER-class tokamaks. The concept is based on the principal of a gun, where a high-pressure propellant gas drives the projectile down the barrel. In the proposed concept, the high gas pressure is created by evaporative explosion of a composite ``pusher'' medium attached behind the DT fuel pellet. The pusher consists of micron-sized conducting particles, (Li, Be, C) embedded uniformly in a D2 ice slug with <5% volume concentration, thus facilitating microwave energy absorption by dissipation of eddy currents flowing within the conducting particles only. Microwave power is delivered to the pusher along a waveguide, which also serves as the pellet launch tube. A scaling law predicts that a pellet of mass M accelerated over a distance L reaches a velocity v (PL/M)^1/3, where P is the gyrotron power.pard[1] P. Parks & F. Perkins, US patent application ``Microwave-Powered Pellet Accelerator,'' No. 11/256/662, October 21, 2005.

  5. Application of Fusion Gyrotrons to Enhanced Geothermal Systems (EGS)

    NASA Astrophysics Data System (ADS)

    Woskov, P.; Einstein, H.; Oglesby, K.

    2013-10-01

    The potential size of geothermal energy resources is second only to fusion energy. Advances are needed in drilling technology and heat reservoir formation to realize this potential. Millimeter-wave (MMW) gyrotrons and related technologies developed for fusion energy research could contribute to enabling EGS. Directed MMW energy can be used to advance rock penetration capabilities, borehole casing, and fracking. MMWs are ideally suited because they can penetrate through small particulate extraction plumes, can be efficiently guided long distances in borehole dimensions, and continuous megawatt sources are commercially available. Laboratory experiments with a 10 kW, 28 GHz CPI gyrotron have shown that granite rock can be fractured and melted with power intensities of about 1 kW/cm2 and minute exposure times. Observed melted rock MMW emissivity and estimated thermodynamics suggest that penetrating hot, hard crystalline rock formations may be economic with fusion research developed MMW sources. Supported by USDOE, Office of Energy Efficiency and Renewable Energy and Impact Technologies, LLC.

  6. Ion Compensation for Space Charge in the Helical Electron Beams of Gyrotrons

    NASA Astrophysics Data System (ADS)

    Manuilov, V. N.; Semenov, V. E.

    2016-06-01

    We solve analytically the problem about ion compensation for the space charge of a helical electron beam in a gyrotron operated in the long-pulse regime. Elementary processes, which take place during ionization of residual gas in the tube under typical pressures of 10-6-10-7 mm Hg, are considered. It is shown that distribution of the space charge is affected mainly by the electrons of the initial beam and slow-moving ions produced by ionization of the residual gas. Steady-state density of ions in the operating space of the gyrotron after the end of the transitional processes is found, as well as the electron density profile in the channel of electron beam transportation. The results obtained allow us to evaluate the pitch-factor variations caused by partial compensations for the potential "sagging" in the gyrotron cavity, thus being useful for analysis of starting currents, efficiency, and mode competition in high-power gyrotrons.

  7. Numerical study on a 0.4 THz second harmonic gyrotron with high power

    SciTech Connect

    Chaojun, Lei; Sheng, Yu; Hongfu, Li; Yinghui, Liu; Xinjian, Niu; Qixiang, Zhao

    2013-07-15

    Terahertz and sub-terahertz science and technology are promising topics today. However, it is difficult to obtain high power source of terahertz wave. In this paper, the mode competition and beam-wave interaction in a gradually tapered cavity are studied to achieve high efficiency of a 0.4THz second harmonic gyrotron in practice. In order to attain high power and stable radiation, the TE{sub 32,5} mode is selected as the operating mode of the desired gyrotron to realize single mode oscillation. The issues of studying on the high-order mode gyrotrons are solved effectively by transforming the generalized telegraphist's equations. The efficiency and output power of the gyrotron under different conditions have been calculated by the code, which is based on the transformed equations. Consequently, the results show that single mode second harmonic radiation with power of over 150 kW at frequency of 0.4 THz could be achieved.

  8. Development of gyrotron traveling-wave tubes at IAP and GYCOM

    NASA Astrophysics Data System (ADS)

    Samsonov, S. V.; Denisov, G. G.; Gachev, I. G.; Bogdashov, A. A.; Mishakin, S. V.; Manuilov, V. N.; Belousov, V. I.; Sobolev, D. I.; Sokolov, E. V.; Soluyanova, E. A.; Tai, E. M.

    2017-08-01

    A brief review of research activity on gyrotron traveling-wave tube amplifiers (gyro-TWTs) with helically corrugated waveguides developing by the Institute of Applied Physics and GYCOM (Nizhny Novgorod, Russia) will be presented.

  9. A 0.4-THz Second Harmonic Gyrotron with Quasi-Optical Confocal Cavity

    NASA Astrophysics Data System (ADS)

    Guan, Xiaotong; Fu, Wenjie; Yan, Yang

    2017-09-01

    Mode density is very relevant for harmonic gyrotron cavity. Theoretical investigations suggest that quasi-optical confocal waveguide performs low mode density and good mode-selective character. By selecting the appropriate mode and optimizing the cavity parameters, the quasi-optical confocal cavity is suitable for high-harmonic terahertz gyrotron without mode competition. In order to verify the theoretical analysis, a 0.4-THz second harmonic gyrotron has been designed and experimented. Driven by a 40-kV, 4.75-A electron beam and 7.51-T magnetic field, the gyrotron prototype could generate 6.44 kW of output power at 395.35 GHz, which corresponds to an electron efficiency of 3.4%. There is no mode competition between the second harmonic and fundamental observed in the experiments.

  10. High Power Microwave Emission of Large and Small Orbit Gyrotron Devices in Rectangular Interaction Structures

    NASA Astrophysics Data System (ADS)

    Hochman, J. M.; Gilgenbach, R. M.; Jaynes, R. L.; Rintamaki, J. I.; Luginsland, J. W.; Lau, Y. Y.; Spencer, T. A.

    1996-11-01

    Experiments utilize large and small orbit e-beam gyrotron devices in a rectangular-cross-section (RCS) gyrotron. This device is being explored to examine polarization control. Other research issues include pulse shortening, and mode competition. MELBA generates electron beams with parameters of: -800kV, 1-10kA diode current, and 0.5-1.0 μ sec pulselengths. The small orbit gyrotron device is converted to a large orbit experiment by running MELBA's annular electron beam through a magnetic cusp. Initial experiments showed an increase in beam alpha (V_perp/V_par) of a factor of ~ 4 between small and large orbit devices. Experimental results from the RCS gyrotron will be compared for large-orbit and small-orbit electron beams. Beam transport data and frequency measurements will be presented. Computer modeling utilizing the MAGIC and E-gun codes will be shown.

  11. A W-band Third Harmonic Gyrotron with an Iris Cavity

    NASA Astrophysics Data System (ADS)

    Sun, Dimin; Chen, Huaibi; Ma, Guowu; Lei, Wenqiang; Chen, Hongbin; Meng, Fanbao

    2014-05-01

    The design and experimental results of a W-band gyrotron operating at the third cyclotron harmonic are presented. The gyrotron is designed to operate at the TE61 mode, which is significantly distinct from competing modes. An iris cavity is employed for the purpose of trapping the third harmonic mode more effectively and lowering its start current. In the experiment, the gyrotron is drived by a triode magnetron injection gun (MIG) which can produce a 45 kV, 3 A electron beam. When maximum axial magnetic field is 1.22 T, a single mode third harmonic gyrotron radiation is observed with the frequency of 94.86 GHz. The maximum output power is 5.5 kW, corresponding to an efficiency of 4%. Another third harmonic mode TE02 is also detected at 88.8 GHz, with maximum output power of 1.5 kW.

  12. Frequency Locking and Stabilization Regimes in High-Power Gyrotrons with Low-Q Resonators

    NASA Astrophysics Data System (ADS)

    Zotova, I. V.; Ginzburg, N. S.; Denisov, G. G.; Rozental', R. M.; Sergeev, A. S.

    2016-02-01

    Using a nonstationary self-consistent model, we analyze the frequency locking and stabilization regimes arising in gyrotrons with low-Q resonators under the action of an external signal or when reflections from a remote nonresonant load are introduced. In the simulations, we used the parameters of high-power gyrotrons designed for controlled thermonuclear fusion with optimized resonator profile. This approach makes it possible to determine output characteristics of the gyrotrons operated in considered regimes taking into account the effect of the incident wave (external or reflected) on the longitudinal field structure with greater precision compared with the earlier results based on the fixed RF-field structure approximation, while qualitative results of the two approaches coincide. Analysis of the effect of reflections from a remote load has demonstrated a substantial dependence of the efficiency of the gyrotron frequency stabilization on the ratio between the characteristic time scale of the synchronism detuning fluctuations and the signal delay time.

  13. Long-Term Operating Experience with High-Power Gyrotron Oscillators

    NASA Astrophysics Data System (ADS)

    Felch, Kevin

    2005-10-01

    High-power, megawatt-class gyrotron oscillators have now been used in electron cyclotron heating (ECH) experiments for several years. The long periods of sustained operation have provided important information about the design limits that had initially been placed on the key elements of the gyrotron. In particular, observations made on recent 110 GHz, 1 MW gyrotrons used in ECH experiments on DIII-D at General Atomics indicate that several of the important components of the device, including the electron guns, interaction cavities and diamond output windows, have performed quite well, while analyses of the electron beam collectors on some of the devices indicate that design limits have often been exceeded. Observations made on these gyrotrons will be summarized and plans to address problem areas will be discussed.

  14. RF Behavior and Launcher Design for a Fast Frequency Step-tunable 236 GHz Gyrotron for DEMO

    NASA Astrophysics Data System (ADS)

    Kalaria, P. C.; Avramidis, K. A.; Franck, J.; Gantenbein, G.; Illy, S.; Jin, J.; Pagonakis, I. Gr.; Thumm, M.; Jelonnek, J.

    2017-03-01

    As part of the EUROfusion project, the conceptual design of a 1 MW 236 GHz hollow-cavity gyrotron is ongoing at IHM, KIT for a DEMOnstration Power Plant (DEMO), along with a 2 MW coaxial-cavity design concept. Fast frequency-tunable gyrotrons (tuning within a few seconds) are recommended for plasma stabilization using a non-steerable antenna. In this work, the mode-selection approach for such a frequency-tunable gyrotron is presented and suitable operating modes for fast frequency tunability are suggested. Magnetic field tuning has been studied as an effective technique to tune the gyrotron operating frequency. The step-tunability of the 236 GHz gyrotron within the frequency range of ±10 GHz in steps of 2-3 GHz is demonstrated in numerical simulations. A hybrid-type Quasi-Optical Launcher (QOL) has been designed for a step-frequency tunable gyrotron with sufficiently high Fundamental Gaussian Mode Content (FGMC).

  15. Development of frequency step tunable 1 MW gyrotron at 131 to 146.5 GHz

    SciTech Connect

    Samartsev, A.; Gantenbein, G.; Dammertz, G.; Illy, S.; Kern, S.; Leonhardt, W.; Schlaich, A.; Schmid, M.; Thumm, M.

    2011-07-01

    Effective control of power absorption in tokamaks and stellarators could be achieved by the frequency tuning of ECH and CD power delivered by high-power gyrotrons. In this report some results of the development of a frequency tunable gyrotron with fused-silica Brewster window are presented. Excitation of several modes at 1 MW power level in the range of frequencies from 131 to 146.5 GHz is achieved. (author)

  16. Influence of emitter ring manufacturing tolerances on electron beam quality of high power gyrotrons

    SciTech Connect

    Pagonakis, Ioannis Gr.; Illy, Stefan; Thumm, Manfred

    2016-08-15

    A sensitivity analysis of manufacturing imperfections and possible misalignments of the emitter ring in the gyrotron cathode structure on the electron beam quality has been performed. It has been shown that a possible radial displacement of the emitter ring of the order of few tens of microns can cause dramatic effects on the beam quality and therefore the gyrotron operation. Two different design approaches are proposed in order to achieve an electron beam which is less sensitive to manufacturing imperfections.

  17. The MTX computer control system for the 400 kilowatt 140 GHz gyrotron

    NASA Astrophysics Data System (ADS)

    Jackson, M. C.; Ferguson, S. W.; Petersen, D. E.

    1991-09-01

    A 400 kilowatt, 140 GHz gyrotron is employed on MTX as a source of direct plasma heating and, additionally, as a driver for a free electron laser, which is used for plasma heating. The control system that operates this gyrotron uses a new graphics oriented software system called TACL (Thaumaturgic Automated Control Logic) developed by the Continuous Electron Beam Accelerator Facility (CEBAF) and owned by DOE. This control language does not require a software specialist, but is easily handled by the engineer or technician working on the system. All control logic and custom displays are entered via graphics oriented editors and no actual lines of code need to be written. The graphics displays make the gyrotron operation quite simple and allow individual users to define displays to meet their own needs or develop one for a specific set of tests to be run. The system, additionally, can be used for logging functions, which have been found quite useful in tracking long term trends in vacion current and calorimetry of gyrotron cooling circuits. The system is composed of one computer (HP 9000 series 300) controlling multiple CAMAC crates located at the various components used in the system. A second series 300 computer is used as a supervisor and is located in the main tokamak control room. This supervisory computer provides remote operation of the gyrotron, and also provides a link to the microwave transport vacuum control (also TACL). The supervisory computer, additionally, is used as a subsystem status summary point for permissives to the gyrotron control system.

  18. Experimental study of a 1 MW, 170 GHz gyrotron oscillator

    NASA Astrophysics Data System (ADS)

    Kimura, Takuji

    A detailed experimental study is presented of a 1 MW, 170 GHz gyrotron oscillator whose design is consistent with the ECH requirements of the International Thermonuclear Experimental Reactor (ITER) for bulk heating and current drive. This work is the first to demonstrate that megawatt power level at 170 GHz can be achieved in a gyrotron with high efficiency for plasma heating applications. Maximum output power of 1.5 MW is obtained at 170.1 GHz in 85 kV, 50A operation for an efficiency of 35%. Although the experiment at MIT is conducted with short pulses (3 μs), the gyrotron is designed to be suitable for development by industry for continuous wave operation. The peak ohmic loss on the cavity wall for 1 MW of output power is calculated to be 2.3 kW/cm2, which can be handled using present cooling technology. Mode competition problems in a highly over-moded cavity are studied to maximize the efficiency. Various aspects of electron gun design are examined to obtain high quality electron beams with very low velocity spread. A triode magnetron injection gun is designed using the EGUN simulation code. A total perpendicular velocity spread of less than 8% is realized by designing a low- sensitivity, non-adiabatic gun. The RF power is generated in a short tapered cavity with an iris step. The operating mode is the TE28,8,1 mode. A mode converter is designed to convert the RF output to a Gaussian beam. Power and efficiency are measured in the design TE28,8,1 mode at 170.1 GHz as well as the TE27,8,1 mode at 166.6 GHz and TE29,8,1 mode at 173.5 GHz. Efficiencies between 34%-36% are consistently obtained over a wide range of operating parameters. These efficiencies agree with the highest values predicted by the multimode simulations. The startup scenario is investigated and observed to agree with the linear theory. The measured beam velocity ratio is consistent with EGUN simulation. Interception of reflected beam by the mod-anode is measured as a function of velocity ratio

  19. High power microwave generation from a large orbit gyrotron

    SciTech Connect

    Lawson, W.; Destler, W.W.; Striffler, C.D.

    1985-10-01

    A study of the production of high power microwave radiation from a large orbit gyrotron in azimuthally periodic boundary systems has been conducted. Linear growth rates have been calculated for the 2 modes of magnetron-like hole-and-slot resonator (HASR) and vane resonator (VR) systems using a general growth rate formalism. The experiment involves the interaction of a 2.3 MeV, 1-2 kA, 5 ns rotating electron layer with the HASR and VR structures. Maximum power levels are about 300 MW in X band from a 10 slot HASR system; about 500 MW in Ku band from a 20 slot VR system; and about 15 MW in K band from about 30 slot systems. The peak efficiency is about 15%. The radiation characteristics are in reasonably good agreement with the theoretical predictions. The reduced power levels for about 30 slot systems are partially attributed to radial mode competition.

  20. Folded waveguide gyrotron traveling-wave-tube amplifier

    SciTech Connect

    Choi, J.J.; Armstrong, C.M.; Ganguly, A.K.; Calise, F.

    1995-03-01

    A compact, low cost gyrotron traveling-wave-tube (gyro-TWT) amplifier capable of producing high-power, broadband, millimeter wave radiation is reported. The interaction circuit is a periodic, magnetic field plane (H plane) bend, transverse folded waveguide employed with a high-power axis-encircling electron beam. Transverse beam modulation and wave amplification in the folded waveguide gyro-TWT are observed in both linear theory and large signal simulations. Calculations from an equivalent circuit model and a three-dimensional electromagnetic code predict a mode coalescing of the first stop-band in a periodic structure. The mode coalescing is verified from experimental measurements. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  1. Effect of electron-cyclotron resonance plasma heating conditions on the low-frequency modulation of the gyrotron power at the L-2M stellarator

    SciTech Connect

    Batanov, G. M.; Borzosekov, V. D.; Kolik, L. V.; Konchekov, E. M. Malakhov, D. V.; Petelin, M. I.; Petrov, A. E.; Sarksyan, K. A.; Skvortsova, N. N.; Stepakhin, V. D.; Kharchev, N. K.

    2015-08-15

    Low-frequency modulation of the gyrotron power at the L-2M stellarator was studied at different modes of plasma confinement. The plasma was heated at the second harmonic of the electron gyrofrequency. The effect of reflection of gyrotron radiation from the region of electron-cyclotron resonance plasma heating, as well as of backscattering of gyrotron radiation from fluctuations of the plasma density, on the modulation of the gyrotron power was investigated.

  2. HLA-Cw*1214 allele arisen via recombination between HLA-Cw*070201 and HLA-Cw*120201.

    PubMed

    Lebedeva, T V; Ohashi, M; Huang, A; Vasconcellos, S; Alosco, S M; Kempenich, J; Yu, N

    2004-12-01

    Allelic polymorphism of the major histocompatibility complex arises mostly from gene conversion. Intralocus gene conversion usually involves limited fragments of DNA, whereas recombination involving large fragments of DNA is considered to be a rare event. During routine sequencing-based typing of donors for the National Marrow Donor Program, a new HLA-C allele was identified in a Caucasian donor. The allele, HLA-Cw*1214, proved to be the product of recombination between HLA-Cw*070201 and HLA-Cw*120201. Exons 1, 2, the 3' end of exon 3 and exon 4 (with one mismatch) belong to HLA-Cw*120201, whereas part of exon 3 belongs to HLA-Cw*070201. Sequencing with primers based in exon 2 and exon 3 showed that intron 2 of the new allele also belonged completely to HLA-Cw*1202. The recombination event apparently occurred within exon 3 with the first point of recombination somewhere between codons 92 and 134 and the second one between codons 157 and 181.

  3. Dependence of the gyrotron efficiency on the azimuthal index of non-symmetric modes

    SciTech Connect

    Dumbrajs, O.; Nusinovich, G. S.; Antonsen, T. M.

    2014-06-15

    Development of MW-class gyrotrons for future controlled fusion reactors requires careful analysis of the stability of high efficiency operation in very high-order modes. In the present paper, this problem is analyzed in the framework of the non-stationary self-consistent theory of gyrotrons. Two approaches are used: the one based on the wave envelope representation of the resonator field and the second one based on representation of this field as a superposition of eigenmodes, whose fields are determined by a self-consistent set of equations. It is shown that at relatively low beam currents, when the maximum efficiency can be realized in the regime of soft self-excitation, the operation in the desired mode is stable even in the case of a very dense spectrum of competing modes. At higher currents, the maximum efficiency can be realized in the regimes with hard self-excitation; here the operation in the desired mode can be unstable because of the presence of some competing modes with low start currents. Two 170 GHz European gyrotrons for the international thermonuclear experimental reactor are considered as examples. In the first one, which is the 2 MW gyrotron with a coaxial resonator, the stability of operation in a chosen TE{sub 34,19}-mode in the presence of two sideband modes with almost equidistant spectrum is analyzed and the region of magnetic fields in which the oscillations of the central mode are stable is determined. The operation of the second gyrotron, which is the 1 MW gyrotron with a cylindrical cavity currently under development in Europe, is studied by using the wave envelope approach. It is shown that high efficiency operation of this gyrotron in the TE{sub 32,9}-mode should be stable.

  4. Testing of an Advanced Internal Mode Converter for a 1.5 MW, 110 GHz Gyrotron

    NASA Astrophysics Data System (ADS)

    Tax, D. S.; Mastovsky, I.; Neilson, J.; Shapiro, M. A.; Sirigiri, J. R.; Temkin, R. J.; Torrezan, A. C.

    2009-11-01

    Megawatt gyrotrons are under development for the electron cyclotron heating (ECH) of plasmas, including ITER. To optimize the efficiency of gyrotrons and of the transmission lines, the internal mode converter (IMC) should output a perfect Gaussian beam. The TE22,6 110 GHz IMC we have implemented consists of a helically-cut launcher and three smooth curved mirrors. The theoretically predicted output beam has waist Wz = Wx = 2.9 cm at the gyrotron window. Cold test measurements using a VNA and a 3-axis scanner were in good agreement with theory with measured beam waists Wz = 2.9 cm and Wx = 2.7 cm. We also installed the IMC in a 110 GHz, 1.5 MW, 3 μs pulsed gyrotron and measured the field pattern with over 40 dB signal to noise accuracy using an rf diode on a 2-axis scanner. Measured beam waists Wz = 4.8 cm and Wx = 4.2 cm compared well with theoretical waists Wz = Wx = 4.7 cm at a plane 124 cm from the gyrotron window.

  5. Development of an Ultra High Frequency Gyrotron with a Pulsed Magnet

    SciTech Connect

    Idehara, T.; Kamada, M.; Tsuchiya, H.; Hayashi, T.; Agusu, La; Mitsudo, S.; Ogawa, I.; Manuilov, V. N.; Naito, K.; Yuyama, T.; Jiang, W.; Yatsui, K.

    2006-01-03

    An ultra-high frequency gyrotron is being developed as a THz radiation source by using a pulsed magnet. We have achieved the highest field intensity of 20.2 T. High frequency operation at the second harmonic will achieve 1.01 THz; the corresponding cavity mode is TE6,11,1. On the other hand, an ultra-high power gyrotron with a pulsed magnet is also being developed as a millimeter to submillimeter wave radiation source. The gyrotron is a large orbit gyrotron (LOG) using an intense relativistic electron beam (IREB). A pulsed power generator 'ETIGO-IV' is applied for generation of the IREB. A prototype relativistic LOG was constructed for fundamental operation. The output of the LOG will achieve 144 GHz and 9 MW; the corresponding cavity mode is TE1,4,1. Cavities for 2nd and 4th harmonic operations were designed by numerical simulation for achievement of higher frequency. The progress of development for prototype high frequency gyrotrons with pulsed magnets is presented.

  6. Development of Dual-Frequency Gyrotron with Triode Magnetron Injection Gun

    NASA Astrophysics Data System (ADS)

    Kajiwara, Ken; Oda, Yasuhisa; Kasugai, Atsushi; Takahashi, Koji; Sakamoto, Keishi

    2011-12-01

    A high power dual-frequency gyrotron is designed and tested. The design is based on a 170 GHz single-frequency gyrotron with a triode magnetron injection gun (MIG). The triode MIG enables to choose variety of oscillation modes for different frequencies with suitable pitch factor, which is the great advantage for a multi-frequency gyrotron. Another frequency of 137 GHz is selected in order to use a 1.853-mm-thick single-disk output window. Cavity modes are TE31,11 and TE25,9 for 170 and 137 GHz, respectively, which have high mode conversion efficiency to the RF beam mode with similar radiation angles. In short-pulse experiments, the maximum power of more than 1.3 MW is achieved with high-efficiency for both frequencies.

  7. Influence of emitter surface roughness on high power fusion gyrotron operation

    NASA Astrophysics Data System (ADS)

    Zhang, Jianghua; Illy, Stefan; Pagonakis, Ioannis Gr; Avramidis, Konstantinos A.; Thumm, Manfred; Jelonnek, John

    2016-02-01

    Emitter surface roughness is one of the important factors of electron beam degradation in magnetron injection gun (MIG) and the decrease of gyrotron efficiency. This paper surveys the influence of emitter surface roughness on the operation of the EU 1 MW 170 GHz gyrotron for ITER for two different gun designs. The emitter surface roughness was taken into account using a simple model. The ESRAY code was used for gun simulation and the EURIDICE code for calculation of the RF interaction in the cavity. The degradation of the beam quality due to the surface roughness is quantitatively studied and, furthermore, the influence on the gyrotron efficiency and the mode competition are investigated. Some dramatic phenomena, such as the generation of magnetically trapped electrons, are predicted at a very high level of roughness.

  8. THz Gyrotron and BWO Designed for Operation in DNP-NMR Spectrometer Magnet

    NASA Astrophysics Data System (ADS)

    Bratman, V. L.; Fedotov, A. E.; Kalynov, Yu. K.; Makhalov, P. B.; Samoson, A.

    2013-12-01

    Dynamic nuclear polarization (DNP) in high-field nuclear magnetic resonance (NMR) spectroscopy requires medium-power terahertz radiation, which nowadays can be provided basically by gyrotrons with superconducting magnets. As the electron cyclotron frequency is very close to the frequency of electron paramagnetic resonance for the same magnetic field, under certain conditions the gyrotron can be installed inside the same solenoid used for NMR spectrometer. This eliminates the need for an additional superconducting magnet, results in a shorter terahertz transmission line, and can make DNP systems practical. In addition to an extremely low-voltage gyrotron ("gyrotrino"), we analyze also advantages of strong magnetic field for a slow-wave electron device as an alternative terahertz source.

  9. Novel linear analysis for a gyrotron oscillator based on a spectral approach

    SciTech Connect

    Genoud, J. Tran, T. M.; Alberti, S.; Braunmueller, F.; Hogge, J.-Ph.; Tran, M. Q.; Guss, W. C.; Temkin, R. J.

    2016-04-15

    With the aim of gaining a better physical insight into linear regimes in gyrotrons, a new linear model was developed. This model is based on a spectral approach for solving the self-consistent system of equations describing the wave-particle interaction in the cavity of a gyrotron oscillator. Taking into account the wall-losses self-consistently and including the main system inhomogeneities in the cavity geometry and in the magnetic field, the model is appropriate to consider real system parameters. The main advantage of the spectral approach, compared with a time-dependent approach, is the possibility to describe all of the stable and unstable modes, respectively, with negative and positive growth rates. This permits to reveal the existence of a new set of eigenmodes, in addition to the usual eigenmodes issued from cold-cavity modes. The proposed model can be used for studying other instabilities such as, for instance, backward waves potentially excited in gyrotron beam tunnels.

  10. Development of over-MW gyrotrons for fusion at 14 GHz to sub-THz frequencies

    NASA Astrophysics Data System (ADS)

    Kariya, T.; Imai, T.; Minami, R.; Sakamoto, K.; Oda, Y.; Ikeda, R.; Shimozuma, T.; Kubo, S.; Idei, H.; Numakura, T.; Tsumura, K.; Ebashi, Y.; Okada, M.; Nakashima, Y.; Yoshimura, Y.; Takahashi, H.; Ito, S.; Hanada, K.; Nagasaki, K.; Ono, M.; Eguchi, T.; Mitsunaka, Y.

    2017-06-01

    Megawatt power gyrotrons are being developed for collaborative electron cyclotron heating (ECH) studies of advanced fusion devices and demonstration power plant (DEMO). (1) In the first experiment of a 300 GHz gyrotron, an output power above 0.5 MW in the TE32,18 single mode was achieved with a pulse width of 2 ms. This was the first observation of MW-scale oscillations in a DEMO-relevant gyrotron mode. It was also found that the reflection at the output window affected the determination of the oscillation mode. Furthermore, several single mode oscillations in the 226-254 GHz range were confirmed, which is important for the step-frequency tunable gyrotron in the sub-THz frequency range. (2) Based on the successful results of the 77 and 154 GHz large helical device (LHD) tubes, a new 154/116 GHz dual-frequency gyrotron with an output of over 1.5 MW is being designed. (3) A new record output of 1.38 MW was obtained using an existing 28 GHz gyrotron. A newly designed tube aimed at achieving a dual-frequency output power of 2 MW at 28 GHz (0.4 MW continuous wave) and 1 MW at 35 GHz was built. In the first experimental test, main mode oscillations were observed at the frequencies of 28.036 and 34.831 GHz with Gaussian-like output beams and output power of 1.27 and 0.48 MW, respectively. A total efficiency of 50% was achieved at 28 GHz operation.

  11. RF behavior of triple-frequency high power fusion gyrotron

    NASA Astrophysics Data System (ADS)

    Kumar, Nitin; Singh, Udaybir; Kumar, Anil; Sinha, A. K.

    2014-05-01

    The RF behavior of high power, triple frequency (170-, 127.5-, and 85 GHz) gyrotron for fusion application is presented in this paper. The operating mode selection is discussed in detail for each corresponding frequencies and TE34,10, TE25,8 and TE17,5 modes are selected as the operating mode for 170 GHz, 127.5 GHz and 85 GHz operation of the device, respectively. The interaction cavity geometry and beam parameters are finalized by the cold cavity analysis and beam-wave interaction simulations. Considering the beam parameters and the beam launching positions in cavity (beam radius), the design of Magnetically Tunable MIG (MT-MIG) is also presented. Results of MT-MIG confirm the beam launching with desired beam parameters at the beam radius corresponding to the selected operating modes for all three frequencies. The CVD diamond window is also designed for RF power transmission. The beam-wave interaction simulations confirm more than 1 MW power at all three frequencies (170-, 127.5-, and 85 GHz).

  12. Testing of a 3 MW, 140 GHz coaxial cavity gyrotron

    SciTech Connect

    Hogge, J.P.; Kreischer, K.; Read, M.E.; Nusinovich, G.; Dumbrajs, O.

    1995-12-31

    A gyrotron designed to produce 3 MW at 140 GHz has been realized and tested The cavity is coaxial, with a desired operating mode of TE{sub 21,13}. The coaxial cavity was designed to have peak ohmic heating of 2.9 kW/cm{sup 2} with less mode competition, and thus a higher electronic efficiency (45%) than the 37% predicted for a hollow cavity with the same mode number. The efficiency calculations were done by a time dependent, multimode simulation. The results of the code are shown. The electron gun is an inverted MIG, with the ``intermediate`` anode at ground potential. The beam voltage and current are 95 kV and 84 A, and the cathode and beam radii, 4.7 cm and 0.815 cm, respectively. The beam velocity ratio, {alpha}, and perpendicular velocity spread, as predicted by EGUN, are 1.44 and 3.7%, respectively. Measurements of the power and frequency spectrum will be presented.

  13. Gyrotron with a sectioned cavity based on excitation of a far-from-cutoff operating mode

    SciTech Connect

    Bandurkin, I. V.; Kalynov, Yu. K.; Osharin, I. V.; Savilov, A. V.

    2016-01-15

    A typical problem of weakly relativistic low-power gyrotrons (especially in the case of operation at high cyclotron harmonics) is the use of long cavities ensuring extremely high diffraction Q-factors for the operating near-cutoff waves. As a result, a great share of the rf power radiated by electrons is spent in Ohmic losses. In this paper, we propose to use a sectioned cavity with π-shifts of the wave phase between sections. In such a cavity, a far-from-cutoff axial mode of the operating cavity having a decreased diffraction Q-factor is excited by the electron beam in a gyrotron-like regime.

  14. Two-wave regime of operation of the high-harmonic gyrotron

    SciTech Connect

    Savilov, A. V.; Denisov, G. G.; Kalynov, Yu. K.; Osharin, I. V.

    2015-04-15

    The use of the two-wave co-generation is proposed as a way to decrease the effective Q-factor of the operating near-cutoff wave of the gyrotron. In this two-wave regime, the operating wave represents a “hot” wave mode formed by two partial “cold” modes (near-cutoff and far-from-cutoff ones) coupled on the electron beam. It is shown that the use of this regime can provide a significant decrease of the Ohmic losses in low-relativistic high-harmonic gyrotrons operating in the THz frequency range.

  15. Real-time, T-ray imaging using a sub-terahertz gyrotron

    NASA Astrophysics Data System (ADS)

    Han, Seong-Tae; Torrezan, Antonio C.; Sirigiri, Jagadishwar R.; Shapiro, Michael A.; Temkin, Richard J.

    2012-06-01

    We demonstrated real-time, active, T-ray imaging using a 0.46 THz gyrotron capable of producing 16 W in continuous wave operation and a pyroelectric array camera with 124-by-124 pixels. An expanded Gaussian beam from the gyrotron was used to maintain the power density above the detection level of the pyroelectric array over the area of the irradiated object. Real-time imaging at a video rate of 48 Hz was achieved through the use of the built-in chopper of the camera. Potential applications include fast scanning for security purposes and for quality control of dry or frozen foods.

  16. Design of interaction cavity for 170 GHz, 1 MW ITER gyrotron

    SciTech Connect

    Kumar, Anil; Kumar, Nitin; Khatun, Hasina; Singh, Udaybir; Sinha, A.K. E-mail: aksinha@ceeri.ernet.in; Vyas, V.

    2011-07-01

    In this paper the design of interaction cavity for 170 GHz, 1 MW gyrotron is presented. An in-house developed code GCOMS has been used for operating mode selection and mode competition. For 170 GHz, 1 MW gyrotron interaction cavity TE28, 7 mode excite as a operating mode at the fundamental harmonic number. The electromagnetic simulator-MAGIC, a Particle-in-Cell (PIC) code has been used for the cold cavity analysis and the beam-wave interaction. More than 1MW output power has been achieved at guiding cavity magnetic field 6.77 T. (author)

  17. FM-cw radar for imaging applications

    NASA Astrophysics Data System (ADS)

    Bjornholt, John E.; Wilson, Terry B.

    1998-10-01

    FM-CW radars operating in the millimeter wave or upper microwave bands can provide low cost, low power solutions for many applications requiring the resolution of targets separated by one meter or less in range. Range resolution of this quality is obtained by sweeping the radar output frequency over several hundred megahertz of bandwidth using modern techniques to achieve extremely good linearity. Because of the short wavelengths at millimeter bands, relatively good angular resolution is achievable with moderately sized antennas. Applications for FM-CW radar sensors include automotive collision warning systems, traffic monitoring, height profiling, terrain profiling, autonomous vehicle navigation, surveillance and site security systems where high resolution is required.

  18. CW (Continuous Wave) Antenna Design and Testing.

    DTIC Science & Technology

    1982-08-01

    it drives up labor cost significantly due to such things as negotations for use of the land and cost of returning the land to its original...sophistication that is incompatible with the operational concept laid out for the CW system. The decision to operate the antenna in close physical proximity to

  19. A CW Gunn Diode Switching Element.

    ERIC Educational Resources Information Center

    Hurtado, Marco; Rosenbaum, Fred J.

    As part of a study of the application of communication satellites to educational development, certain technical aspects of such a system were examined. A current controlled bistable switching element using a CW Gunn diode is reported on here. With modest circuits switching rates of the order of 10 MHz have been obtained. Switching is initiated by…

  20. A CW Gunn diode bistable switching element.

    NASA Technical Reports Server (NTRS)

    Hurtado, M.; Rosenbaum, F. J.

    1972-01-01

    Experiments with a current-controlled bistable switching element using a CW Gunn diode are reported. Switching rates of the order of 10 MHz have been obtained. Switching is initiated by current pulses of short duration (5-10 ns). Rise times of the order of several nanoseconds could be obtained.

  1. CW arc-lamp-pumped alexandrite lasers

    SciTech Connect

    Samelson, H.; Walling, J.C.; Wernikowski, T.; Harter, D.J.

    1988-06-01

    The performance characteristics of arc-lamp- (Xe and Hg) pumped, CW alexandrite lasers are described in detail. The modes of operation considered are free running, tuned, and repetitively Q-switched. The experimental arrangement and apparatus are also outlined. The experimental results are discussed in terms of a steady-state model, and the areas of agreement and difficulty are pointed out.

  2. Cw operation of the FMIT RFQ accelerator

    SciTech Connect

    Cornelius, W.D.

    1985-01-01

    Recently, we have achieved reliable cw operation of the Fusion Materials Irradiation Test (FMIT) radio-frequency quadrupole (RFQ) accelerator. In addition to the operational experiences in achieving this status, some of the modifications of the vacuum system, cooling system, and rf structure are discussed. Preliminary beam-characterization results are presented. 10 refs., 8 figs.

  3. Generation of 1.5-kW, 1-THz coherent radiation from a gyrotron with a pulsed magnetic field.

    PubMed

    Glyavin, M Yu; Luchinin, A G; Golubiatnikov, G Yu

    2008-01-11

    To cover a so-called terahertz gap in available sources of coherent electromagnetic radiation, the gyrotron with a pulsed solenoid producing up to a 40 T magnetic field has been designed, manufactured, and tested. At a 38.5 T magnetic field, the gyrotron generated coherent radiation at 1.022 THz frequency in 50 musec pulses. The microwave power and energy per pulse were about 1.5 kW and 75 mJ, respectively. Details of the gyrotron design, manufacturing, operation and measurements of output radiation are given.

  4. 3D CFDTD PIC Simulation Study on Low-Frequency Oscillations in a Gyrotron

    NASA Astrophysics Data System (ADS)

    Lin, M. C.; Smithe, D. N.

    2011-10-01

    Low-frequency oscillations (LFOs) have been observed in a high average power gyrotron and the trapped electron population contributing to the oscillation has been measured. As high average power gyrotrons are the most promising millimeter wave source for thermonuclear fusion research, it is important to get a better understanding of this parasitic phenomenon to avoid any deterioration of the electron beam quality thus reducing the gyrotron efficiency. However, understanding of the LFOs remains incomplete and a full picture of this parasitic phenomenon has not been seen yet. In this work, we use a 3D conformal finite-difference time-domain (CFDTD) particle-in-cell (PIC) method to accurately and efficiently study the LFOs in a magnetron injection gun (MIG) of a high average power gyrotron. Employing a highly parallelized computation, the model can be simulated in time domain more realistically. LFOs have been obtained in a 3D time domain simulation for the first time. From our preliminary simulation studies, it is found that not only magnetic compression profile but initial velocity or velocity ratio play an important role in the operation of a MIG electron gun. In addition, the secondary emission effects on the LFOs are also studied. Detailed results will be presented. Work supported by the U.S. Department of Energy under Grant No. DE-SC0004436.

  5. Performance history and upgrades for the DIII-D gyrotron complex

    DOE PAGES

    Lohr, J.; Anderson, J. P.; Cengher, M.; ...

    2015-03-12

    The gyrotron installation on the DIII-D tokamak has been in operation at the second harmonic of the electron cyclotron resonance since the mid-1990s. Prior to that a large installation of ten 60 GHz tubes was operated at the fundamental resonance. The system has been upgraded regularly and is an everyday tool for experiments on DIII-D.

  6. A Fully-Sealed Carbon-Nanotube Cold-Cathode Terahertz Gyrotron

    PubMed Central

    Yuan, Xuesong; Zhu, Weiwei; Zhang, Yu; Xu, Ningsheng; Yan, Yang; Wu, Jianqiang; Shen, Yan; Chen, Jun; She, Juncong; Deng, Shaozhi

    2016-01-01

    Gigahertz to terahertz radiation sources based on cold-cathode vacuum electron technology are pursued, because its unique characteristics of instant switch-on and power saving are important to military and space applications. Gigahertz gyrotron was reported using carbon nanotube (CNT) cold-cathode. It is reported here in first time that a fully-sealed CNT cold-cathode 0.22 THz-gyrotron is realized, typically with output power of 500 mW. To achieve this, we have studied mechanisms responsible for CNTs growth on curved shape metal surface, field emission from the sidewall of a CNT, and crystallized interface junction between CNT and substrate material. We have obtained uniform growth of CNTs on and direct growth from cone-cylinder stainless-steel electrode surface, and field emission from both tips and sidewalls of CNTs. It is essential for the success of a CNT terahertz gyrotron to have such high quality, high emitting performance CNTs. Also, we have developed a magnetic injection electron gun using CNT cold-cathode to exploit the advantages of such a conventional gun design, so that a large area emitting surface is utilized to deliver large current for electron beam. The results indicate that higher output power and higher radiation frequency terahertz gyrotron may be made using CNT cold-cathode electron gun. PMID:27609247

  7. A Fully-Sealed Carbon-Nanotube Cold-Cathode Terahertz Gyrotron

    NASA Astrophysics Data System (ADS)

    Yuan, Xuesong; Zhu, Weiwei; Zhang, Yu; Xu, Ningsheng; Yan, Yang; Wu, Jianqiang; Shen, Yan; Chen, Jun; She, Juncong; Deng, Shaozhi

    2016-09-01

    Gigahertz to terahertz radiation sources based on cold-cathode vacuum electron technology are pursued, because its unique characteristics of instant switch-on and power saving are important to military and space applications. Gigahertz gyrotron was reported using carbon nanotube (CNT) cold-cathode. It is reported here in first time that a fully-sealed CNT cold-cathode 0.22 THz-gyrotron is realized, typically with output power of 500 mW. To achieve this, we have studied mechanisms responsible for CNTs growth on curved shape metal surface, field emission from the sidewall of a CNT, and crystallized interface junction between CNT and substrate material. We have obtained uniform growth of CNTs on and direct growth from cone-cylinder stainless-steel electrode surface, and field emission from both tips and sidewalls of CNTs. It is essential for the success of a CNT terahertz gyrotron to have such high quality, high emitting performance CNTs. Also, we have developed a magnetic injection electron gun using CNT cold-cathode to exploit the advantages of such a conventional gun design, so that a large area emitting surface is utilized to deliver large current for electron beam. The results indicate that higher output power and higher radiation frequency terahertz gyrotron may be made using CNT cold-cathode electron gun.

  8. The design of a multi-harmonic step-tunable gyrotron

    NASA Astrophysics Data System (ADS)

    Qi, Xiang-Bo; Du, Chao-Hai; Zhu, Juan-Feng; Pan, Shi; Liu, Pu-Kun

    2017-03-01

    The theoretical study of a step-tunable gyrotron controlled by successive excitation of multi-harmonic modes is presented in this paper. An axis-encircling electron beam is employed to eliminate the harmonic mode competition. Physics images are depicted to elaborate the multi-harmonic interaction mechanism in determining the operating parameters at which arbitrary harmonic tuning can be realized by magnetic field sweeping to achieve controlled multiband frequencies' radiation. An important principle is revealed that a weak coupling coefficient under a high-harmonic interaction can be compensated by a high Q-factor. To some extent, the complementation between the high Q-factor and weak coupling coefficient makes the high-harmonic mode potential to achieve high efficiency. Based on a previous optimized magnetic cusp gun, the multi-harmonic step-tunable gyrotron is feasible by using harmonic tuning of first-to-fourth harmonic modes. Multimode simulation shows that the multi-harmonic gyrotron can operate on the 34 GHz first-harmonic TE11 mode, 54 GHz second-harmonic TE21 mode, 74 GHz third-harmonic TE31 mode, and 94 GHz fourth-harmonic TE41 mode, corresponding to peak efficiencies of 28.6%, 35.7%, 17.1%, and 11.4%, respectively. The multi-harmonic step-tunable gyrotron provides new possibilities in millimeter-terahertz source development especially for advanced terahertz applications.

  9. TESTS AND PERFORMANCE ON THE SIX GYROTRON SYSTEM ON THE DIII-D TOKAMAK

    SciTech Connect

    LOHR,J; GORELOV,YA; KAJIWARA,K; PONCE,D; CALLIS,RW; FERRON,JR; GREENFIELD,CM; LAHAYE,RJ; PINSKER,RI; PRATER,R; WADE,MR; ELLIS,RA

    2002-09-01

    A271 TESTS AND PERFORMANCE ON THE SIX GYROTRON SYSTEM ON THE DIII-D TOKAMAK. The DIII-D gyrotron complex for electron cyclotron heating (ECH) and electron cyclotron current drive (ECCD) has been expanded to include five operational gyrotrons with a sixth being commissioned. The generated rf power exceeds 4.0 MW and the transmission lines deliver about 80% of this power to the tokamak. Among the experiments performed during the most recent campaign, the installation has been used to achieve stabilization of the m/n=2/1 and 3/2 neoclassical tearing modes, to control the rate of current penetration early in the discharge, and to study ECCD contributions to advanced tokamak discharges with high bootstrap fractions. Observations of the thermal performance of CVD diamond output windows have shown good agreement with theoretical predictions, but have revealed a number of interesting phenomena connected with impurities, including points of visible light emission at hot spots identified by infrared measurements. One window was cleaned in situ by alumina grit blasting and Raman spectra verified the removal of some surface contamination. A significant new capability is the simultaneous control of the output power of the entire array of gyrotrons by the DIII-D plasma control system. This allows a predetermined electron temperature evolution to be followed at a specific location in the plasma and opens a new group of experimental possibilities leading to the achievement of higher levels of tokamak performance.

  10. To the theory of high-power gyrotrons with uptapered resonators

    SciTech Connect

    Dumbrajs, O.; Nusinovich, G. S.

    2010-05-15

    In high-power gyrotrons it is desirable to combine an optimal resonator length with the optimal value of the resonator quality factor. In resonators with the constant radius of the central part, the possibilities of this combination are limited because the quality factor of the resonator sharply increases with its length. Therefore the attempts to increase the length for maximizing the efficiency leads to such increase in the quality factor which makes the optimal current too small. Resonators with slightly uptapered profiles offer more flexibility in this regard. In such resonators, one can separate optimization of the interaction length from optimization of the quality factor because the quality factor determined by diffractive losses can be reduced by increasing the angle of uptapering. In the present paper, these issues are analyzed by studying as a typical high-power 17 GHz gyrotron which is currently under development in Europe for ITER (http://en.wikipedia.org/wiki/ITER). The effect of a slight uptapering of the resonator wall on the efficiency enhancement and the purity of the radiation spectrum in the process of the gyrotron start-up and power modulation are studied. Results show that optimal modification of the shape of a slightly uptapered resonator may result in increasing the gyrotron power from 1052 to 1360 kW.

  11. CONDITIONING AND PROTECTION CIRCUITRY FOR EXTERNAL MODULATION OF A PREPROGRAMMED GYROTRON CATHODE VOLTAGE COMMAND WAVEFORM

    SciTech Connect

    PONCE,D; FERRON,J.R; LEGG,R.A

    2003-10-01

    OAK-B135 The modulating voltages applied to the DIII-D gyrotrons are controlled by reference signals which are synthesized by arbitrary waveform generators.These generators allow ECH operators to pre-program reference waveforms consisting of ramps, flat tops, and various modulation shapes. This capability is independent of the DIII-D central timing and waveform facilities, which provides the ECH operators operational flexibility. The waveform generators include an amplitude modulation input, providing a means to control the pre-programmed waveform externally. This input is being used to allow the DIII-D plasma control system (PCS) to control gyrotron power in response top selected feedback signals. As the PCS control signal could potentially modulate the gyrotrons beyond operational limits or otherwise in a manner leading to recalcitrant rf generation, the control signal is conditioned so that its effect upon the ECH pre-programmed reference waveform is limited by conditions set by the ECH operators. The design of the circuitry which restricts the range over which the PCS control signal may modulate the reference waveform will be discussed. Test and DIII-D experimental results demonstrating the utility and effectiveness of gyrotron power modulated by the PCS will be presented.

  12. Start-Up Scenario in Gyrotrons with a Nonstationary Microwave-Field Structure

    NASA Astrophysics Data System (ADS)

    Nusinovich, G. S.; Yeddulla, M.; Antonsen, T. M., Jr.; Vlasov, A. N.

    2006-03-01

    Megawatt class gyrotrons operate in very high-order modes. Therefore, control of a gyrotron oscillator’s start-up is important for excitation of the desired mode in the presence of the many undesired modes. Analysis of such scenario using the self-consistent code MAGY [M. Botton , IEEE Trans. Plasma Sci. 26,ITPSBD0093-3813 882 (1998)10.1109/27.700860] reveals that during start-up not only mode amplitudes vary in time, but also their axial structure can be time dependent. Simulations done for a 1.5 MW gyrotron show that the excitation of a single operating TE22,6 mode can exhibit a sort of intermittency when, first, it is excited as a mode whose axial structure extends outside the interaction cavity, then it ceases and then reappears as a mode mostly localized in the cavity. This phenomenon makes it necessary to analyze start-up scenarios in such gyrotrons with the use of codes that account for the possible evolution of field profiles.

  13. A comparative study on the modeling of dynamic after-cavity interaction in gyrotrons

    NASA Astrophysics Data System (ADS)

    Avramidis, K. A.; Ioannidis, Z. C.; Kern, S.; Samartsev, A.; Pagonakis, I. Gr.; Tigelis, I. G.; Jelonnek, J.

    2015-05-01

    There are cases where gyrotron interaction simulations predict dynamic After-Cavity Interaction (ACI). In dynamic ACI, a mode is excited by the electron beam at a dominant frequency in the gyrotron cavity and, at the same time, this mode is also interacting with the beam at a different frequency in the non-linear uptaper after the cavity. In favor of dynamic ACI being a real physical effect, there are some experimental findings that could be attributed to it, as well as some physical rationale indicating the possibility of a mode being resonant with the beam at different frequencies in different regions. However, the interaction codes used in dynamic ACI prediction up to now are based on simplifications that put questions on their capability of correctly simulating this effect. In this work, the shortcomings of the usual simplifications with respect to dynamic ACI modeling, namely, the trajectory approach and the single-frequency boundary condition, are identified. Extensive simulations of dynamic ACI cases are presented, using several "in-house" as well as commercial codes. We report on the comparison and the assessment of different modeling approaches and their results and we discuss whether, in some cases, dynamic ACI can be a numerical artifact or not. Although the possibility of existence of dynamic ACI in gyrotrons is not disputed, it is concluded that the widely used trajectory approach for gyrotron interaction modeling is questionable for simulating dynamic ACI and can lead to misleading results.

  14. The gyrotron - a natural source of high-power orbital angular momentum millimeter-wave beams

    NASA Astrophysics Data System (ADS)

    Thumm, M.; Sawant, A.; Choe, M. S.; Choi, E. M.

    2017-08-01

    Orbital angular momentum (OAM) of electromagnetic-wave beams provides further diversity to multiplexing in wireless communication. The present report shows that higher-order mode gyrotrons are natural sources of high-power OAM millimeter (mm) wave beams. The well-defined OAM of their rotating cavity modes operating at near cutoff frequency has been derived by photonic and electromagnetic wave approaches.

  15. Steady-state operation of 170 GHz 1 MW gyrotron for ITER

    NASA Astrophysics Data System (ADS)

    Kasugai, A.; Sakamoto, K.; Takahashi, K.; Kajiwara, K.; Kobayashi, N.

    2008-05-01

    A 170 GHz gyrotron has been developed at JAEA, which has achieved operation of 1 MW/800 s and up to 55% efficiency. This is the first demonstration of a gyrotron achieving and even exceeding the ITER operating requirements of 1 MW/500 s and 50% efficiency. In addition the gyrotron demonstrated operation for 1 h with an output power of 0.6 MW. The oscillation was stable with all cooling water temperatures and vacuum pressure reaching equilibrium conditions during the pulse length at either power level. The successful operation was aided by a very low level of stray radiation (~2% of the output power), which contributed to fast conditioning and stable operation. The output power from the gyrotron was coupled into an ITER sized corrugated waveguide (phi = 63.5 mm) via a matching optics unit with a total of 0.97 MW transmitted to the dummy load after two miter bends and ~7 m of a waveguide without any trouble. These results give an encouraging outlook for the success of the ITER electron cyclotron heating and current drive system.

  16. Numerical study of the start-up scenario of a 670 GHz gyrotron operation at TE31,8 mode

    NASA Astrophysics Data System (ADS)

    Pu, Ruifeng; Sinitsyn, Oleksandr; Nusinovich, Gregory; Ireap Team

    2011-10-01

    In order to develop a system to detect concealed radioactive materials, we are designing a 670 GHz gyrotron with sufficient power to cause breakdown in the air. Design studies of the cavity and the magnetron injection gun (MIG) of this gyrotron had already been presented. We concluded study of simple start-up regime for this 670GHz gyrotron operating at TE31,8 mode and found that at the fundamental cyclotron harmonics, the operating mode can be excited and the competitor modes will be suppressed. Currently we are studying gyrotron operating on the second cyclotron harmonics using the same electron gun. Preliminary studies show that if the higher harmonics mode is excited first, it will suppress competitors of the fundamental mode. Using available MIG data, we are performing numerical simulation using MAGY. The results of these simulations can be illustrative for our future experiments, and the results of the study will be presented at the conference. Supported by ONR.

  17. CHARACTERISTICS OF DIAMOND WINDOWS ON THE 1 MW, 110 GHz GYROTRON SYSTEMS ON THE DIII-D TOKAMAK

    SciTech Connect

    Y.A. GORELOV; J. LOHR; R.W. CALLIS; D. PONCE

    2002-08-01

    Diamond disks made using the chemical vapor deposition (CVD) technique are now in common use as gyrotron output windows. The low millimeter wave losses and excellent thermal conductivity of diamond have made it possible to use such windows in gyrotrons with {approx}1 MW output power and pulse length up to and greater than 10 s. A ubiquitous characteristic of diamond gyrotron windows is the presence of apparent hot spots in the infrared images registered during rf pulses. Many of these spots are co-located with bright points seen in visible video images. The spots do not seem to compromise the integrity of the windows. Analysis of the infrared observations on several different gyrotrons operating at the DIII-D tokamak are reported.

  18. A 100 MV cryomodule for CW operation

    SciTech Connect

    Charles Reece

    2005-07-10

    A cryomodule designed for high-gradient CW operation has been built at Jefferson Lab. The Renascence cryomodule is the final prototype of a design for use in the 12 GeV CEBAF upgrade. The module uses eight 7-cell 1497 MHz cavities to be individually powered by 13 kW klystrons. Specifications call for providing >109 MV CW with < 250 W of dynamic heat at 2.07 K. The module incorporates a new generation of tuners and higher power input waveguides. A mixture of the new HG and LL cavity shapes are used. A new high thermal conductivity RF feedthrough has been developed and used on the 32 HOM coupler probes of Renascence. The cryomodule assembly is complete. Testing is to begin late June. Design features and initial test data will be presented.

  19. Effects of electron beam parameters and velocity spread on radio frequency output of a photonic band gap cavity gyrotron oscillator

    NASA Astrophysics Data System (ADS)

    Singh, Ashutosh; Jain, P. K.

    2015-09-01

    In this paper, the effects of electron beam parameters and velocity spread on the RF behavior of a metallic photonic band gap (PBG) cavity gyrotron operating at 35 GHz with TE041-like mode have been theoretically demonstrated. PBG cavity is used here to achieve a single mode operation of the overmoded cavity. The nonlinear time-dependent multimode analysis has been used to observe the beam-wave interaction behavior of the PBG cavity gyrotron, and a commercially available PIC code "CST Particle Studio" has been reconfigured to obtain 3D simulation results in order to validate the analytical values. The output power for this typical PBG gyrotron has been obtained ˜108 kW with ˜15.5% efficiency in a well confined TE041-like mode, while all other competing modes have significantly low values of power output. The output power and efficiency of a gyrotron depend highly on the electron beam parameters and velocity spread. The influence of several electron beam parameters, e.g., beam voltage, beam current, beam velocity pitch factor, and DC magnetic field, on the PBG gyrotron operations has been investigated. This study would be helpful in optimising the electron beam parameters and estimating accurate RF output power of the high frequency PBG cavity based gyrotron oscillators.

  20. Strong yellow emission of high-conductivity bulk ZnO single crystals irradiated with high-power gyrotron beam

    NASA Astrophysics Data System (ADS)

    Kato, Kosaku; Qiu, Hongsong; Khutoryan, Eduard M.; Tatematsu, Yoshinori; Tani, Masahiko; Idehara, Toshitaka; Yamaguchi, Yuusuke; Fukunari, Masafumi; Maeda, Yuto; Takayama, Kyoya; Minami, Yuki; Empizo, Melvin John F.; Kurihara, Takayuki; Yamanoi, Kohei; Shimizu, Toshihiko; Takano, Keisuke; Sarukura, Nobuhiko; Fukuda, Tsuguo; Yoshimura, Masashi; Nakajima, Makoto

    2017-07-01

    We report the strong yellow emission of bulk ZnO single crystals irradiated with the high-power gyrotron beam. Hydrothermally grown bulk crystals with high conductivity are irradiated at room temperature with up to 60-W output of a sub-terahertz gyrotron wave source. During gyrotron irradiation, the high-conductivity crystals exhibit intense emissions with a peak of around 2 eV (600 nm) and a longer-wavelength tail. The sample temperatures were also elevated from room temperature to above 1000 K by irradiation. However, when heated up to 1250 K using a heater without irradiation, the ZnO crystals do not exhibit similar visible emissions. We then use the generalized Planck's radiation in non-equilibrium states as an explanation of our experimental observations. The emission peak intensity can be enhanced by the gyrotron-induced non-equilibrium states, and the emission peak position can be related to the Urbach energy. With high intensities in the visible wavelengths, the emissions of the irradiated crystals can be readily observed with our bare eyes or with inexpensive digital cameras. As the spatial distribution of the yellow emission reflects the gyrotron beam pattern, the bulk ZnO single crystals can then be utilized for the quick diagnosis of gyrotron beam patterns and positions.

  1. Effects of electron beam parameters and velocity spread on radio frequency output of a photonic band gap cavity gyrotron oscillator

    SciTech Connect

    Singh, Ashutosh; Jain, P. K.

    2015-09-15

    In this paper, the effects of electron beam parameters and velocity spread on the RF behavior of a metallic photonic band gap (PBG) cavity gyrotron operating at 35 GHz with TE{sub 041}–like mode have been theoretically demonstrated. PBG cavity is used here to achieve a single mode operation of the overmoded cavity. The nonlinear time-dependent multimode analysis has been used to observe the beam-wave interaction behavior of the PBG cavity gyrotron, and a commercially available PIC code “CST Particle Studio” has been reconfigured to obtain 3D simulation results in order to validate the analytical values. The output power for this typical PBG gyrotron has been obtained ∼108 kW with ∼15.5% efficiency in a well confined TE{sub 041}–like mode, while all other competing modes have significantly low values of power output. The output power and efficiency of a gyrotron depend highly on the electron beam parameters and velocity spread. The influence of several electron beam parameters, e.g., beam voltage, beam current, beam velocity pitch factor, and DC magnetic field, on the PBG gyrotron operations has been investigated. This study would be helpful in optimising the electron beam parameters and estimating accurate RF output power of the high frequency PBG cavity based gyrotron oscillators.

  2. A new MIG-3 gyrotron complex for creation and heating of plasma in the L-2M stellarator and the first experimental results

    NASA Astrophysics Data System (ADS)

    Batanov, G. M.; Belousov, V. I.; Bondar', Yu. F.; Borzosekov, V. D.; Vasil'kov, D. G.; Grebenshchikov, S. E.; Ivannikov, I. A.; Kolik, L. V.; Konchekov, E. M.; Malakhov, D. V.; Matveev, N. V.; Meshcheryakov, A. I.; Petrov, A. E.; Sarksyan, K. A.; Skvortsova, N. N.; Stepakhin, V. D.; Kharchev, N. K.; Khol'nov, Yu. V.; Tai, E. M.

    2013-12-01

    The characteristics of a new MIG-3 gyrotron complex for creating and heating plasma in the L-2M stellarator are presented. The first experimental results using the complex are reported. The complex consists of two three-electrode GYCOM gyrotrons of the new generation with electron beam energy recuperation, a high-voltage modulator that enables both separate and simultaneous operation of the two gyrotrons, and a control/data-recording unit. The total specific power to be inserted into plasma reaches 5 MW/m3 when both gyrotrons in operation.

  3. Theoretical study on a 0.6 THz third harmonic gyrotron

    NASA Astrophysics Data System (ADS)

    Yuan, Xuesong; Lan, Ying; Ma, Chunyan; Han, Yu; Yan, Yang

    2011-10-01

    A theoretical study on a 0.6 THz third harmonic TE37 mode gyrotron oscillator is reported in this paper in order to develop a compact, reliable, and high power terahertz radiation source. An output power of 4 kW can be generated in the TE37 mode (0.6 THz) at a resonant magnetic field of 7.86 T by the gyrotron oscillator operating at 55 kV/2 A with an electron beam radius of 0.32 mm. A magnetron injection gun (MIG) with high compression ratio has been designed. The simulation results of MIG show that the velocity ratio α is 1.37, and the perpendicular velocity spread and parallel velocity spread are 6.1% and 8.9%, respectively.

  4. Theoretical study on a 0.6 THz third harmonic gyrotron

    SciTech Connect

    Yuan Xuesong; Ma Chunyan; Han Yu; Yan Yang; Lan Ying

    2011-10-15

    A theoretical study on a 0.6 THz third harmonic TE{sub 37} mode gyrotron oscillator is reported in this paper in order to develop a compact, reliable, and high power terahertz radiation source. An output power of 4 kW can be generated in the TE{sub 37} mode (0.6 THz) at a resonant magnetic field of 7.86 T by the gyrotron oscillator operating at 55 kV/2 A with an electron beam radius of 0.32 mm. A magnetron injection gun (MIG) with high compression ratio has been designed. The simulation results of MIG show that the velocity ratio {alpha} is 1.37, and the perpendicular velocity spread and parallel velocity spread are 6.1% and 8.9%, respectively.

  5. Development of a 1.5 MW coaxial gyrotron at 165 GHz

    SciTech Connect

    Iatrou, C.T.; Dammertz, G.; Piosczyk, B.; Zhang, S.C.

    1995-12-31

    The development of a 165 GHz - 1.5 MW coaxial cavity gyrotron operating in the TE{sub 31,17} mode is presented. The selection of the operating frequency and mode are based on the limitations imposed by the maximum field of the existing SC magnet at FZK, the use of the inverse MIG of the 140 GHz-TE{sub 28,16} coaxial gyrotron, and the possibility of transforming the operating mode to a whispering gallery mode (WGM), appropriate for the dual-beam q.o. output coupler and the two output rf windows. The cavity with a tapered and longitudinally corrugated inner rod, the nonlinear uptaper and a new rf window are under construction. First experiments with an axial output tube are foreseen in November 1995.

  6. Amplification of picosecond pulses in a 140-GHz gyrotron-traveling wave tube.

    PubMed

    Kim, H J; Nanni, E A; Shapiro, M A; Sirigiri, J R; Woskov, P P; Temkin, R J

    2010-09-24

    An experimental study of picosecond pulse amplification in a gyrotron-traveling wave tube (gyro-TWT) has been carried out. The gyro-TWT operates with 30 dB of small signal gain near 140 GHz in the HE₀₆ mode of a confocal waveguide. Picosecond pulses show broadening and transit time delay due to two distinct effects: the frequency dependence of the group velocity near cutoff and gain narrowing by the finite gain bandwidth of 1.2 GHz. Experimental results taken over a wide range of parameters show good agreement with a theoretical model in the small signal gain regime. These results show that in order to limit the pulse broadening effect in gyrotron amplifiers, it is crucial to both choose an operating frequency at least several percent above the cutoff of the waveguide circuit and operate at the center of the gain spectrum with sufficient gain bandwidth.

  7. Suppression criteria of parasitic mode oscillations in a gyrotron beam tunnel

    SciTech Connect

    Kumar, Nitin; Singh, Udaybir; Sinha, A. K.; Singh, T. P.

    2011-02-15

    This paper presents the design criteria of the parasitic mode oscillations suppression for a periodic, ceramic, and copper loaded gyrotron beam tunnel. In such a type of beam tunnel, the suppression of parasitic mode oscillations is an important design problem. A method of beam-wave coupling coefficient and its mathematical formulation are presented. The developed design criteria are used in the beam tunnel design of a 42 GHz gyrotron to be developed for the Indian TOKAMAK system. The role of the thickness and the radius of the beam tunnel copper rings to obtain the developed design criteria are also discussed. The commercially available electromagnetic code CST and the electron trajectory code EGUN are used for the simulations.

  8. A ferromagnetic shim insert for NMR magnets - Towards an integrated gyrotron for DNP-NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Ryan, Herbert; van Bentum, Jan; Maly, Thorsten

    2017-04-01

    In recent years high-field Dynamic Nuclear Polarization (DNP) enhanced NMR spectroscopy has gained significant interest. In high-field DNP-NMR experiments (⩾400 MHz 1H NMR, ⩾9.4 T) often a stand-alone gyrotron is used to generate high microwave/THz power to produce sufficiently high microwave induced B1e fields at the position of the NMR sample. These devices typically require a second, stand-alone superconducting magnet to operate. Here we present the design and realization of a ferroshim insert, to create two iso-centers inside a commercially available wide-bore NMR magnet. This work is part of a larger project to integrate a gyrotron into NMR magnets, effectively eliminating the need for a second, stand-alone superconducting magnet.

  9. Design of 132 GHz gyrotron with 3 GHz tunability for 200 MHz DNP/NMR spectrometer

    NASA Astrophysics Data System (ADS)

    Kumar, Nitin; Singh, Udaybir; Sinha, Ashok Kumar

    2015-01-01

    A complete design of 132 GHz gyrotron for 200 MHz DNP-NMR spectroscopy application is presented in this article. The design is performed considering a frequency tunability range of 3 GHz and output power around 100 W. A smooth frequency tunability is achieved via the excitation of TE03p modes (p = 1-6) through the variation of cavity magnetic field. The start oscillation current calculation is performed to estimate the required magnetic field for each TE03p mode. Cold cavity analysis and beam-wave interaction computation are carried out for the estimation of quality factor, resonant frequency corresponding to each TE03p mode, axial electric field profile and output power. Other important components of gyrotron such as magnetron injection gun, non-linear taper and RF window are also designed considering the smooth frequency tunability a main design parameter.

  10. Generation of high charge state platinum ions on vacuum arc plasma heated by gyrotron radiation.

    PubMed

    Yushkov, G Yu; Vodopyanov, A V; Nikolaev, A G; Izotov, I V; Savkin, K P; Golubev, S V; Oks, E M

    2014-02-01

    The hybrid high charge metal ion source based on vacuum arc plasma heated by gyrotron radiation into simple magnetic trap has been developed. Two types of magnetic traps were used: a mirror configuration and a cusp one with inherent "minimum-B" structure. Pulsed high power (>100 kW) gyrotrons with frequency 37.5 GHz and 75 GHz were used for heating the vacuum arc plasma injected into the traps. Two different ways were used for injecting the metal plasma-axial injection by a miniature arc source located on-axis near the microwave window, and simultaneous radial injection by a number of sources mounted radially at the midplane of the traps. This article represents all data gathered for platinum ions, thus making comparison of the experimental results obtained with different traps and injections convenient and accurate.

  11. A ferromagnetic shim insert for NMR magnets - Towards an integrated gyrotron for DNP-NMR spectroscopy.

    PubMed

    Ryan, Herbert; van Bentum, Jan; Maly, Thorsten

    2017-04-01

    In recent years high-field Dynamic Nuclear Polarization (DNP) enhanced NMR spectroscopy has gained significant interest. In high-field DNP-NMR experiments (⩾400MHz (1)H NMR, ⩾9.4T) often a stand-alone gyrotron is used to generate high microwave/THz power to produce sufficiently high microwave induced B1e fields at the position of the NMR sample. These devices typically require a second, stand-alone superconducting magnet to operate. Here we present the design and realization of a ferroshim insert, to create two iso-centers inside a commercially available wide-bore NMR magnet. This work is part of a larger project to integrate a gyrotron into NMR magnets, effectively eliminating the need for a second, stand-alone superconducting magnet. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Design of 84 GHz 500 kW Gyrotron for Technological Millimeter Wave Applications

    NASA Astrophysics Data System (ADS)

    Singh, Udaybir; Kumar, Nitin; Kumar, Anil; Purohit, L. P.; Sinha, A. K.

    2011-04-01

    In this paper, the design and the numerical simulation of the 84 GHz, 500 kW gyrotron at first harmonic operation for technological applications is described. The operating mode of the gyrotron is TE10, 4. Various in-house developed and commercially available computer codes are used for the design purpose. The triode-type magnetron injection gun with the accelerating voltage 70-kV, the beam current 10-A and the maximum transverse velocity spread less than 5% is designed. The preliminary design is obtained by using some trade-off equations. The mode selection, the cold cavity and the beam-wave interaction analysis are discussed for the design of weakly tapered open resonator type of the interaction cavity. The parametric analysis of the interaction cavity and the electron gun is also presented.

  13. Numerical Simulation of a Double-anode Magnetron Injection Gun for 110 GHz, 1 MW Gyrotron

    NASA Astrophysics Data System (ADS)

    Singh, Udaybir; Kumar, Nitin; Purohit, L. P.; Sinha, Ashok K.

    2010-07-01

    A 40 A double-anode magnetron injection gun for a 1 MW, 110 GHz gyrotron has been designed. The preliminary design has been obtained by using some trade-off equations. The electron beam analysis has been performed by using the commercially available code EGUN and the in-house developed code MIGANS. The operating mode of the gyrotron is TE22,6 and it is operated in the fundamental harmonic. The electron beam with a low transverse velocity spread ( δ {β_{ bot max }} = 2.26% ) and the transverse-to-axial velocity ratio of the electron beam (α) = 1.37 is obtained. The simulated results of the MIG obtained with the EGUN code have been validated with another trajectory code TRAK. The results on the design output parameters obtained by both the codes are in good agreement. The sensitivity analysis has been carried out by changing the different gun parameters to decide the fabrication tolerance.

  14. Design of Electron Gun for 1.5 MW, 140 GHz Gyrotron

    NASA Astrophysics Data System (ADS)

    Singh, Udaybir; Kumar, Nitin; Purohit, L. P.; Sinha, A. K.

    2011-02-01

    This paper presents the design of the triode type electron gun for a 140 GHz, 1.5 MW gyrotron with the transverse to the axial velocity ratio of the beam 1.4 and the transverse velocity spread 1.28%. The operating mode of the gyrotron is TE24,8 and it is operated in the fundamental harmonic. The analytic trade-off equations for the electron gun design have been used to estimate the initial gun parameters. The electron trajectory tracing program has been used to optimize the electron gun design. The parametric dependences of modulating anode voltage, beam voltage and cathode magnetic field on the beam quality has also been studied.

  15. Gyrotrons for High-Power Terahertz Science and Technology at FIR UF

    NASA Astrophysics Data System (ADS)

    Idehara, Toshitaka; Sabchevski, Svilen Petrov

    2017-01-01

    In this review paper, we present the recent progress in the development of a series of gyrotrons at the Research Center for Development of Far-Infrared Region, University of Fukui, that have opened the road to many novel applications in the high-power terahertz science and technology. The current status of the research in this actively developing field is illustrated by the most representative examples in which the developed gyrotrons are used as powerful and frequency-tunable sources of coherent radiation operating in a continuous-wave regime. Among them are high-precision spectroscopic techniques (most notably dynamic nuclear polarization-nuclear magnetic resonance, electron spin resonance, X-ray detected magnetic resonance, and studies of the hyperfine splitting of the energy levels of positronium), treatment and characterization of advanced materials, and new medical technologies.

  16. A radiatively pumped CW CO2 laser

    NASA Technical Reports Server (NTRS)

    Insuik, R. J.; Christiansen, W. H.

    1984-01-01

    A proof of principle experiment to demonstrate the physics of a radiatively pumped laser has been carried out. For the first time, a blackbody cavity has optically pumped a CW CO2 laser. Results are presented from a series of experiments using mixtures of CO2, He, and Ar in which maximum output power was obtained with a 20 percent CO2-15 percent He-65 percent Ar mixture. The dependence of the output power on the blackbody temperature and the cooling gas flow rate is also discussed. By appropriately varying these parameters, continuous output powers of 8-10 mW have been achieved.

  17. Time-domain theory of gyrotron traveling wave amplifiers operating at grazing incidence

    SciTech Connect

    Ginzburg, N. S.; Sergeev, A. S.; Zotova, I. V.; Zheleznov, I. V.

    2015-01-15

    Time-domain theory of the gyrotron traveling wave tube (gyro-TWT) operating at grazing incidence has been developed. The theory is based on a description of wave propagation by a parabolic equation. The results of the simulations are compared with experimental results of the observation of subnanosecond pulse amplification in a gyro-TWT consisting of three gain sections separated by severs. The theory developed can also be used successfully for a description of amplification of monochromatic signals.

  18. Time domain analysis of a gyrotron traveling wave amplifier with misaligned electron beam

    SciTech Connect

    Wang, Qiushi Peng, Shuyuan; Luo, Jirun

    2014-08-15

    This article develops a time-domain theory to study the beam-wave interaction in gyrotron traveling wave amplifier (gyro-TWA) with a misaligned electron beam. The effects of beam misalignment on the TE{sub 01} mode gyro-TWA operating at the fundamental are discussed. Numerical results show that the effect of misalignment is less obvious when the input power is larger, and the influences of misalignment on the stable gain and the stable time are basically opposite.

  19. Conceptual design of a Gyrotron-driven superconducting ECR ion source

    SciTech Connect

    Countryman, P.J.; Lyneis, C.M.; Wolgast, R.C.

    1989-03-01

    The conceptual design for a superconducting Electron Cyclotron Resonance Ion Source (ECRIS) is presented. It is designed to take advantage of frequency scaling in ECRIS and be driven at 28 GHz by a laboratory scale gyrotron. The superconducting coils are surrounded by a warm bore iron yoke. Possible applications include cyclotrons, heavy-ion synchrotrons, ion implantation in semiconductors, and experiments in atomic physics. 10 refs., 5 figs., 1 tab.

  20. Modelling and simulation of new generation powerful gyrotrons for the fusion research

    NASA Astrophysics Data System (ADS)

    Sabchevski, S.; Zhelyazkov, I.

    2007-04-01

    One of the important issues related with the cyclotron resonance heating (CRH) and current drive of fusion plasmas in thermonuclear reactors (tokamaks and stellarators) is the development of multi-megawatt class gyrotrons. There are generally three stages of the implementation of that task, notably (i) elaborating a novel generation of software tools for the physical modelling and simulation of such kind of gyrotrons, (ii) their computer aided design (CAD) and construction on the basis of the simulation's results, and finally, (iii) gyrotrons' testing in real experimental conditions. This tutorial paper concerns the first item-the development of software tools. In co-operation with the Institute for Pulsed Power and Microwave Technology at the Forschungszentrum Karlsruhe, Germany, and Centre de Recherches en Physique des Plasmas at École Polytechnique Fédérale de Lausanne, Switzerland, we work on the conceptual design of the software tools under development. The basic conclusions are that the numerical codes for gyrotrons' modelling should possess the following essential characteristics: (a) portability, (b) extensibility, (c) to be oriented toward the solution of practical problems (i.e., elaborating of computer programs that can be used in the design process), (d) to be based on self-consistent 3D physical models, which take into account the departure from axial symmetry, and (e) ability to simulate time dependent processes (electrostatic PIC simulation) alongside with a trajectory analysis (ray tracing simulation). Here, we discuss how various existing numerical codes have to be improved and implemented via the advanced programming technologies for state-of-the-art computer systems including clusters, grid, parallel platforms, and supercomputers.

  1. Cold cavity analysis for 35 GHz gyrotron interaction cavity using free space method

    SciTech Connect

    Kumar, Nitin; Saran, Sudeep; Singh, Udaybir; Yadav, Vivek; Sinha, Ashok K.; Jha, B.; Jain, P.K.; Singh, T.P.

    2011-07-01

    The interaction cavity simulated, designed and fabricated for the 35 GHz gyrotron is verified experimentally. Free space method for the Q value and resonant frequency measurement is used in the experiments. The WR22 waveguide based antenna system, Agilent Vector Network Analyzer are used as the experimental set-up in the cavity measurement. The simulation results for the same cavity are also obtained by using the electromagnetic simulator MAGIC for the comparison. (author)

  2. Evaluation of Cathode Heater Assembly for 42 GHz, 200 kW Gyrotron

    NASA Astrophysics Data System (ADS)

    Sharma, S. K.; Singh, Narendra Kumar; Singh, Udaybir; Khatun, Hasina; Kumar, Nitin; Alaria, M. K.; Raju, R. S.; Jain, P. K.; Sinha, A. K.

    2014-09-01

    In this paper, the evaluation of cathode-heater assembly of magnetron injection gun (MIG) for 42 GHz, 200 kW gyrotron is presented. The cathode-heater assembly is purchased from M/S SEMICON.The cathode-heater assembly is experimentally studied in three different conditions; in a belljar system, during vacuum processing of MIG and during MIG testing to ensure the required rise of cathode surface temperature for pre-set heater power.

  3. Suppression and nonlinear excitation of parasitic modes in second harmonic gyrotrons operating in a very high order mode

    SciTech Connect

    Nusinovich, Gregory S.; Pu, Ruifeng; Granatstein, Victor L.

    2015-07-06

    In recent years, there was an active development of high-power, sub-terahertz (sub-THz) gyrotrons for numerous applications. For example, a 0.67 THz gyrotron delivering more than 200 kW with about 20% efficiency was developed. This record high efficiency was achieved because the gyrotron operated in a high-order TE{sub 31,8}-mode with the power of ohmic losses less than 10% of the power of outgoing radiation. That gyrotron operated at the fundamental cyclotron resonance, and a high magnetic field of about 27 T was created by a pulse solenoid. For numerous applications, it is beneficial to use gyrotrons at cyclotron harmonics which can operate in available cryomagnets with fields not exceeding 15 T. However, typically, the gyrotron operation at harmonics faces severe competition from parasitic modes at the fundamental resonance. In the present paper, we consider a similar 0.67 THz gyrotron designed for operation in the same TE{sub 31,8}-mode, but at the second harmonic. We focus on two nonlinear effects typical for interaction between the fundamental and second harmonic modes, viz., the mode suppression and the nonlinear excitation of the mode at the fundamental harmonic by the second harmonic oscillations. Our study includes both the analytical theory and numerical simulations performed with the self-consistent code MAGY. The simulations show that stable second harmonic operation in the TE{sub 31,8} mode is possible with only modest sacrifice of efficiency and power.

  4. Towards a 1 MW, 170 GHz gyrotron design for fusion application

    NASA Astrophysics Data System (ADS)

    Kumar, Anil; Kumar, Nitin; Singh, Udaybir; Bhattacharya, Ranajoy; Yadav, Vivek; Sinha, A. K.

    2013-03-01

    The electrical design of different components of 1 MW, 170 GHz gyrotron such as, magnetron injection gun, cylindrical interaction cavity and collector and RF window is presented in this article. Recently, a new project related to the development of 170 GHz, 1 MW gyrotron has been started for the Indian Tokamak. TE34,10 mode is selected as the operating mode after studied the problem of mode competition. The triode type geometry is selected for the design of magnetron injection gun (MIG) to achieve the required beam parameters. The maximum transverse velocity spread of 3.28% at the velocity ratio of 1.34 is obtained in simulations for a 40 A, 80 kV electron beam. The RF output power of more than 1 MW with 36.5% interaction efficiency without depressed collector is predicted by simulation in single-mode operation at 170 GHz frequency. The simulated single-stage depressed collector of the gyrotron predicted the overall device efficiencies >55%. Due to the very good thermal conductivity and very weak dependency of the dielectric parameters on temperature, PACVD diamond is selected for window design for the transmission of RF power. The in-house developed code MIGSYN and GCOMS are used for initial geometry design of MIG and mode selection respectively. Commercially available simulation tools MAGIC and ANSYS are used for beam-wave interaction and mechanical analysis respectively.

  5. NRL quasioptical gyrotron program. Final report, November 1, 1991--October 31, 1993

    SciTech Connect

    Fliflet, A.

    1997-06-01

    The quasioptical gyrotron (QOG) has been under development as a high power, tunable source for tokamak plasma heating applications. Given the critical importance of source efficiency for large-scale ESCH applications, understanding the causes of the low QOG efficiency and finding ways of improving it became a top priority for the current NRL program. The importance of the present work is that is represents new insight into the factors controlling the efficiency of quasioptical gyrotrons. The author has demonstrated that the technique of mode priming provides a method for improving efficiency via enhanced mode detuning and leads to more stable single-mode operation of highly over-moded resonators. The latter feature is an important consideration for output coupler and rf transmission system optimization and can make the QOG less sensitive to external influences such as window reflections. He has shown that a prebunching resonator is readily implemented in the quasioptical configuration. It is relatively free of the problems of spurious modes and cross-talk which plague over-moded prebunching cavities in conventional gyrotrons. The observation of almost 18% efficiency represents a doubling of the previous best single-mode results. Further improvements are expected from the optimization of start-up conditions and the study of the effects of the second harmonic interaction.

  6. Analysis and Alignment of a Gyrotron RF Beam on the DIII-D ECH System

    NASA Astrophysics Data System (ADS)

    Gorelov, Y. A.; Lohr, J.; Torrezan, A.; Anderson, J. P.; Ponce, D.; Cengher, M.

    2014-10-01

    The DIII-D ECH transmission line installation comprises seven runs of up to 80 meters of 31.75 mm diameter waveguide, with transmission efficiencies from 69%-79%. The efficiency depends on the purity of the HE1,1 mode in the waveguide. The Gaussian rf beam from a gyrotron is converted to the HE1,1 waveguide mode with a single focusing mirror in the matching optics unit (MOU) that places a waist, w0 = 19 mm, at the input of the waveguide. At tilt angles Θ of less than two degrees and small offsets Δ of less than 3 mm, the mode conversion from a pure HE1,1 mode increases as Θ2 and Δ2 respectively. The rf beam from the newest gyrotron was recorded in free space propagation at 10 cm intervals from the gyrotron window using an infrared camera. These data were used for phase retrieval calculations to optimize the design of the focusing mirror in the MOU. The mirror position was then set to align the rf beam with the waveguide axis. The measurement was repeated for the rf beam radiated from a short length of waveguide and the HE1,1 content was 87%. This is slightly low compared to the measurements of the other waveguides. Work supported by the US DOE under DE-FC02-04ER54698.

  7. Update on the DIII-D ECH system: experiments, gyrotrons, advanced diagnostics, and controls

    NASA Astrophysics Data System (ADS)

    Lohr, John; Brambila, Rigoberto; Cengher, Mirela; Gorelov, Yuri; Grosnickle, William; Moeller, Charles; Ponce, Dan; Torrezan, Antonio; Ives, Lawrence; Reed, Michael; Blank, Monica; Felch, Kevin; Parisuaña, Claudia; LeViness, Alexandra

    2017-08-01

    The ECH system on DIII-D is continuing to be upgraded, while simultaneously being operated nearly daily for plasma experiments. The latest major hardware addition is a new 117.5 GHz gyrotron, which generated 1.7 MW for short pulses during factory testing. A new gyrotron control system based on Field Programmable Gate Array (FPGA) technology with very high speed system data acquisition has significantly increased the flexibility and reliability of individual gyrotron operation. We have improved the performance of the fast mirror scanning, both by increasing the scan speeds and by adding new algorithms for controlling the aiming using commands generated by the Plasma Control System (PCS). The system is used for transport studies, ELM control, current profile control, non-inductive current generation, suppression of MHD modes, startup assist, plasma density control, and other applications. A program of protective measures, which has been in place for more than two years, has eliminated damage to hardware and diagnostics caused by overdense operation. Other activities not directly related to fusion research have used the ECH system to test components, study methods for improving production of semiconductor junctions and materials, and test the feasibility of using ground based microwave systems to power satellites into orbit.

  8. Microwave method for synthesis of micro- and nanostructures with controllable composition during gyrotron discharge

    NASA Astrophysics Data System (ADS)

    Batanov, German M.; Borzosekov, Valentin D.; Golberg, Dmitri; Iskhakova, Ludmila D.; Kolik, Leonid V.; Konchekov, Evgeny M.; Kharchev, Nikolai K.; Letunov, Alexander A.; Malakhov, Dmitry V.; Milovich, Filipp O.; Obraztsova, Ekaterina A.; Petrov, Alexander E.; Ryabikina, Irina G.; Sarksian, Karen A.; Stepakhin, Vladimir D.; Skvortsova, Nina N.

    2016-01-01

    We introduce an approach toward the synthesis of micro- and nanostructures under nonequilibrium microwave discharges within metal-dielectric powder mixtures induced by powerful microwave gyrotron radiation. A new plasma-chemical reactor capable of sustaining a discharge regime with an afterglow phase of an order of magnitude longer than the gyrotron pulse duration was constructed for these experiments. In the nonequilibrium conditions of such a discharge, plasma-induced exothermic chemical reactions leading to the synthesis of various compounds were initiated. The synthesized structures were deposited on the reactor walls and on the impurity particles within the reactor. This method was tested under gyrotron-initiated discharges within various metal-dielectric powder mixtures of titanium-boron, molybdenum-boron, titanium-silicon-boron, molybdenum-boron nitride, molybdenum-tungsten-boron nitride, and so on. Depending on the powder mixture composition, reactor atmosphere, and other parameters, micro- and nanosized particles of boron nitride, titanium diboride, molybdenum boride, titanium boride, molybdenum, and molybdenum oxide, were synthesized, detected, and analyzed.

  9. Experimental Research on a 1.5 MW, 110 GHz Gyrotron

    NASA Astrophysics Data System (ADS)

    Shapiro, M. A.; Hidaka, Y.; Choi, E. M.; Mastovsky, I.; Sirigiri, J. R.; Tax, D. S.; Temkin, R. J.; Neilson, J.

    2008-11-01

    We report experimental research on the after cavity interaction (ACI) in a 1.5-MW, 110-GHz gyrotron with an internal mode converter operating in 3 microsecond pulses. Recent experiments with a single-stage depressed collector revealed the effects of the ACI, a second interaction that occurs after the electron beam passes through the intended primary interaction region. The ACI causes re-absorption of the microwave power and broadening of the spent electron beam energy distribution, thus leading to a significant reduction in gyrotron efficiency. The broadening of the spent electron beam energy spectrum, which results in degraded performance of the depressed collector, has been experimentally verified. Ways to minimize the ACI are currently being investigated. Also, a new internal mode converter, consisting of a helically-cut launcher and four smooth curved mirrors, has been designed and fabricated. The cold test shows a good agreement with the theoretical Gaussian beam pattern. This new converter will be hot tested shortly in the gyrotron.

  10. A 0.33-THz second-harmonic frequency-tunable gyrotron

    NASA Astrophysics Data System (ADS)

    Zheng-Di, Li; Chao-Hai, Du; Xiang-Bo, Qi; Li, Luo; Pu-Kun, Liu

    2016-02-01

    Dynamics of the axial mode transition process in a 0.33-THz second-harmonic gyrotron is investigated to reveal the physical mechanism of realizing broadband frequency tuning in an open cavity circuit. A new interaction mechanism about propagating waves, featured by wave competition and wave cooperation, is presented and provides a new insight into the beam-wave interaction. The two different features revealed in the two different operation regions of low-order axial modes (LOAMs) and high-order axial modes (HOAMs) respectively determine the characteristic of the overall performance of the device essentially. The device performance is obtained by the simulation based on the time-domain nonlinear theory and shows that using a 12-kV/150-mA electron beam and TE-3,4 mode, the second harmonic gyrotron can generate terahertz radiations with frequency-tuning ranges of about 0.85 GHz and 0.60 GHz via magnetic field and beam voltage tuning, respectively. Additionally, some non-stationary phenomena in the mode startup process are also analyzed. The investigation in this paper presents guidance for future developing high-performance frequency-tunable gyrotrons toward terahertz applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 61471007, 61531002, 61522101, and 11275206) and the Seeding Grant for Medicine and Information Science of Peking University, China (Grant No. 2014-MI-01).

  11. Design, Development & Functional Validation of Magnets system in support of 42 GHz Gyrotron in India

    NASA Astrophysics Data System (ADS)

    Pradhan, S.; Raj, P.; Prasad, U.; Ghate, M.; Khristi, Y.; Panchal, A.; Bhavsar, D.; Banudha, M.; Kedia, S.; Sharma, A. N.; Kanabar, D.; Parghi, B.

    2017-07-01

    A multi institutional initiative is underway towards the development of 42 GHz, 200 kW gyrotron system in India under the frame work of Department of Science and Technology, Government of India. Indigenous realization comprising of design, fabrication, prototypes and functional validations of an appropriate Magnet System is one of the primary technological objective of these initiatives. The 42 GHz gyrotron magnet system comprises of a warm gun magnet, a NbTi/Cu based high homogenous superconducting cavity magnet and three warm collector magnets. The superconducting cavity magnet has been housed inside a low loss cryostat. The magnet system has been designed in accordance with gyrotron physics and engineering considerations respecting highly homogenous spatial field profile as well as maintaining steep gradient as per the compression and velocity ratios between the emission and resonator regions. The designed magnet system further ensures the co-linearity of the magnetic axis with that of the beam axis with custom winding techniques apart from a smooth collection of beam with the collector magnet profiles. The designed magnets have been wound after several R & D validations. The superconducting magnet has been housed inside a low loss designed cryostat with in-built radial and axial alignment flexibilities to certain extent. The cryostat further houses liquid helium port, liquid nitrogen ports, current communication ports, ports for monitoring helium level and other instrumentations apart from over-pressure safety intensive burst disks etc. The entire magnet system comprising of warm and superconducting magnets has been installed and integrated in the Gyrotron test set-up. The magnet system has been aligned in both warm and when the superconducting cavity magnet is cold. The integrated geometric axes have been experimentally ensured as well as the field profiles have been measured with the magnets being charged. Under experimental conditions, all magnets including

  12. On the dependence of the efficiency of a 240 GHz high-power gyrotron on the displacement of the electron beam and on the azimuthal index

    SciTech Connect

    Dumbrajs, O.; Avramidis, K. A.; Franck, J.; Jelonnek, J.

    2014-01-15

    Two issues in the cavity design for a Megawatt-class, 240 GHz gyrotron are addressed. Those are first, the effect of a misaligned electron beam on the gyrotron efficiency and second, a possible azimuthal instability of the gyrotron. The aforementioned effects are important for any gyrotron operation, but could be more critical in the operation of Megawatt-class gyrotrons at frequencies above 200 GHz, which will be the anticipated requirement of DEMO. The target is to provide some basic trends to be considered during the refinement and optimization of the design. Self-consistent calculations are the base for simulations wherever possible. However, in cases for which self-consistent models were not available, fixed-field results are presented. In those cases, the conservative nature of the results should be kept in mind.

  13. Moderate-power cw fibre lasers

    SciTech Connect

    Kurkov, Andrei S; Dianov, Evgenii M

    2004-10-31

    A review of the development and investigation of moderate-power (10{sup -1}-10{sup 2} W) cw fibre lasers is presented. The properties of optical fibres doped with rare-earth ions and methods for fabricating double-clad fibres are considered. The methods for fabrication of fibre Bragg gratings used as selective reflectors are discussed and the grating properties are analysed. The main pump schemes for double-clad fibre lasers are described. The properties of fibre lasers doped with neodymium, ytterbium, erbium, thulium, and holmium ions are also considered. The principles of fabrication of Raman converters of laser radiation based on optical fibres of different compositions are discussed and the main results of their studies are presented. It is concluded that fibre lasers described in the review can produce moderate-power radiation at any wavelength in the spectral range from 0.9 to 2 {mu}m. (review)

  14. Very high speed cw digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Pérez-López, Carlos; de La Torre-Ibarra, Manuel H.; Mendoza Santoyo, Fernando

    2006-10-01

    It is reported for the first time the use of a very high speed camera in digital holographic interferometry with an out of plane sensitivity setup. The image plane holograms of a spherical latex balloon illuminated by a cw laser were acquired at a rate of 4000 frames per second, representing a time spacing between holograms of 250 microseconds, for 512 × 512 pixels at 8 bits resolution. Two types of tests were accomplished for a proof of principle of the technique, one with no constrains on the object which meant random movements due to non controlled environmental air currents, and the other with specific controlled conditions on the object. Results presented correspond to a random sample of sequential digital holograms, chosen from a 1 second exposure, individually Fourier processed in order to perform the usual comparison by subtraction between consecutive pairs thus obtaining the phase map of the object out of plane displacement, shown as a movie.

  15. A double-beam magnetron-injection gun for third-harmonic continuous wave 1-THz gyrotron

    NASA Astrophysics Data System (ADS)

    Glyavin, M.; Manuilov, V.; Idehara, T.

    2013-12-01

    The concept of a continuous wave 1-kW/1-THz gyrotron operated at the third cyclotron harmonic of the transverse electric TE9,7 operating mode has been developed. To suppress the mode competition effects in a terahertz gyrotron, we propose a scheme with two generating helical electron beams (HEBs) formed in a double-beam triode magnetron-injection gun (MIG), where both emitters of the electron beams are located on a common cathode of the conventional MIG. An optimal geometry of the MIG electrodes is found. It is shown that in a proposed scheme two HEBs having close pitch factors and a moderate velocity spread can be formed. This makes them suitable for high-efficiency single-mode generation in the high frequency gyrotron at high harmonic.

  16. A double-beam magnetron-injection gun for third-harmonic continuous wave 1-THz gyrotron

    SciTech Connect

    Glyavin, M.; Manuilov, V.; Idehara, T.

    2013-12-15

    The concept of a continuous wave 1-kW/1-THz gyrotron operated at the third cyclotron harmonic of the transverse electric TE{sub 9,7} operating mode has been developed. To suppress the mode competition effects in a terahertz gyrotron, we propose a scheme with two generating helical electron beams (HEBs) formed in a double-beam triode magnetron-injection gun (MIG), where both emitters of the electron beams are located on a common cathode of the conventional MIG. An optimal geometry of the MIG electrodes is found. It is shown that in a proposed scheme two HEBs having close pitch factors and a moderate velocity spread can be formed. This makes them suitable for high-efficiency single-mode generation in the high frequency gyrotron at high harmonic.

  17. Power-Stabilization of High Frequency Gyrotrons Using a Double PID Feedback Control for Applications to High Power THz Spectroscopy

    NASA Astrophysics Data System (ADS)

    Idehara, Toshitaka; Kuleshov, Alexei; Ueda, Keisuke; Khutoryan, Eduard

    2013-11-01

    High stabilization of the output power of high frequency gyrotrons for high power THz spectroscopy is an important issue in order to extend the applications of gyrotrons to wider subjects. For this objective, we tried a PID feedback control on a heater current of a triode magnetron injection gun (MIG) for stabilization of an electron beam current and an additional PID control of an anode voltage of the gun for direct stabilization of output power. This double PID control achieved effective responses for the stabilization of output power in both slow (from several tens seconds to several minutes) and fast (from milliseconds to seconds) time scales.

  18. A method for suppression of spurious fundamental-harmonic waves in gyrotrons operating at the second cyclotron harmonic

    SciTech Connect

    Kalynov, Yu. K.; Osharin, I. V.; Savilov, A. V.

    2016-05-15

    A typical problem of gyrotrons operating at high harmonics of the electron cyclotron frequency is the suppression of parasitic near-cutoff waves excited at lower harmonics. In this paper, a method for a significant improvement of the selectivity of the second-harmonic gyrotrons is proposed. This method is based on the use of quasi-regular cavities with short irregularities, which provide different effects on the process of excitation of the operating second-harmonic wave and the spurious fundamental-harmonic wave by the electron beam.

  19. Design of 28 GHz, 200 kW Gyrotron for ECRH Applications

    NASA Astrophysics Data System (ADS)

    Yadav, Vivek; Singh, Udaybir; Kumar, Nitin; Kumar, Anil; Deorani, S. C.; Sinha, A. K.

    2013-01-01

    This paper presents the design of 28 GHz, 200 kW gyrotron for Indian TOKAMAK system. The paper reports the designs of interaction cavity, magnetron injection gun and RF window. EGUN code is used for the optimization of electron gun parameters. TE03 mode is selected as the operating mode by using the in-house developed code GCOMS. The simulation and optimization of the cavity parameters are carried out by using the Particle-in-cell, three dimensional (3-D)-electromagnetic simulation code MAGIC. The output power more than 250 kW is achieved.

  20. Demonstration of Steady State Operation with 1 MW of 170 GHz gyrotron for ITER

    SciTech Connect

    Kasugai, Atsushi; Takahashi, Koji; Kajiwara, Ken; Kobayashi, Noriyuki; Sakamoto, Keishi

    2007-09-28

    A quasi-steady-state operation of 1 MW/800 s with the efficiency of 55%, which exceeded 1 MW/500 s/50% of the performance required in ITER, was demonstrated in a 170 GHz gyrotron. The oscillation characteristics in the long pulse operation was clarified, and the operation scenario to the hard self-excitation region for the high efficiency oscillation was newly established by controlling a pitch factor of the electron and the cavity magnetic field during the pulse with fixed beam voltage in the triode MIG. The result gives a clear outlook for the success of ECH and ECCD in ITER.

  1. Gyrotron Output Power Stabilization by PID Feedback Control of Heater Current and Anode Voltage

    NASA Astrophysics Data System (ADS)

    Khutoryan, E. M.; Idehara, T.; Kuleshov, A. N.; Ueda, K.

    2014-12-01

    To provide stable output power of a gyrotron during long operation time the power stabilization was achieved by two schemes with PID feedback control of heater current and anode voltage. It was based on the dependence of the output power on both the anode voltage and the beam current and also on the dependence of the beam current on the gun heater current. Both schemes provided decrease of the power standard deviation to 0.3-0.5%. The comparison between parameters of both schemes is discussed in the paper.

  2. Scaling of an 85 GHz Gyrotron to Operate at 94 GHz

    DTIC Science & Technology

    1989-09-06

    Laboratory P.O. Box Y Mail Stop 3 Building 9201 -2 Oak Ridge , TN 37830 Attn: Dr. A. England 1 copy Office of Naval Research 800 N. Quincy Street Arlington...observed up to 135 kW at high current ( 12 A). Efficiency was 32% at low current ( 4 A), in agreement with the theoretically predicted value. Lower...the gyrotron was expected to operate, 3.57 - 3.78 Tesla. The theoretically predicted maximum efficiency is at 12 A. Figure 4 shows the calculated power

  3. Measurement of Plasma-Neutralized Super-Vacuum Currents in a Gyrotron Configuration

    DTIC Science & Technology

    1990-02-16

    Ridge National Laboratory P.O. Box Y Mail Stop 3 Building 9201 -2 Oak Ridge , TN 37830 Attn: Dr. A. England 1 copy Office of Naval Research 800 N...public release; distribution 2b. DECLASSIFICATION /DOWNGRADING SCHEDULE unlimited. 4 . PERFORMING ORGANIZATION REPORT NUMBER(S) 5. MONITORING...Neutralized Super-Vacuum Currents in a Gyrotron Configuration 12 . PERSONAL AUTHOR(S) Kirkpatrick, D.A.*, Gold, S.H., Manheimer, W.M., Black, W.M., Kinkead. A.K

  4. ECH system using an 88 GHz gyrotron for the WT-3 Tokamak

    SciTech Connect

    Maekawa, T.; Terumichi, Y.; Yoshimura, S.; Matsunaga, K.

    1996-02-01

    A new ECH/ECCD system using an 88GHz gyrotron for the WT-3 Tokamak ({ital R}{sub 0}=65{ital cm}, {ital a}=20{ital cm}, {ital B}{sub {ital T}0}{le}1.75{ital T}) is under making. Taking advantage of a relatively short wavelength and the Gaussian beam output mode, we plan ECH/ECCD experiments with a strongly focused beam in order to achieve local modification of the electron temperature and current profiles for investigation of MHD instabilities. {copyright} {ital 1996 American Institute of Physics.}

  5. Operation of a 3 MW, 140 GHz gyrotron with a coaxial cavity

    SciTech Connect

    Advani, R.N.; Pedrozzi, M.; Kreischer, K.E.; Temkin, R.J.; Read, M.E.

    1998-12-31

    Experimental results will be presented here for a high power, high frequency coaxial gyrotron. The designed goal for this experiment is to produce 3 MW, at 140 GHz in the TE 21,13 mode with an efficiency of at least 30%. In the experiment the inner conductor extends from the electron gun to the output. The main advantages of the coaxial conductor are: causes rarefied mode spectrum around the design mode; reduces the quality factor of competing modes; volume modes (higher radial index) can be chosen (which increases the output power); and reduces voltage depression.

  6. Megavolt, multi-kiloamp K(sub )a-band gyrotron oscillator experiment

    NASA Astrophysics Data System (ADS)

    Black, W. M.; Gold, S. H.; Fliflet, A. W.; Kirkpatrick, D. A.; Manheimer, W. M.; Lee, R. C.; Granatstein, V. L.; Hardesty, D. L.; Kinkead, A. K.; Sucy, M.

    1989-03-01

    High peak power K sub a band gyrotron oscillator experiment is reported. This experiment operated at 35 GHz in a sub a TE sub 62 mode, using a 1 to 1.35 MeV, multi-kiloamp beam from the VEBA pulseline accelerator. The use of an apertured anode configuration provided improved beam quality compared to earlier experiments that were carried out in a foilless diode geometry. As a result, the peak power has increased to approximately 275 MW with peak efficiencies exceeding 10 percent. The experimental results are in reasonable agreement with the predictions of theory.

  7. Coupler for coupling gyrotron whispering gallery mode RF into HE11 waveguide

    DOEpatents

    Neilson, Jeffrey M

    2015-02-24

    A cylindrical waveguide with a mode converter transforms a whispering gallery mode from a gyrotron cylindrical waveguide with a helical cut launch edge to a quasi-Gaussian beam suitable for conveyance through a corrugated waveguide. This quasi-Gaussian beam is radiated away from the waveguide using a spiral cut launch edge, which is in close proximity to a first mode converting reflector. The first mode converting reflector is coupled to a second mode converting reflector which provides an output free-space HE11 mode wave suitable for direct coupling into a corrugated waveguide. The radiated beam produced at the output of the second mode converting reflector is substantially circular.

  8. Feasibility study of a cryogenically cooled window for high-power gyrotrons

    SciTech Connect

    Haste, G.R.; Kimrey, H.D.; Prosise, J.D.

    1986-07-01

    Single-crystal sapphire is currently in use as the material for output windows in high-power microwave tubes, particularly gyrotrons. These windows are currently being cooled by fluorocarbon fluids at near-room temperatures. There are, however, several advantages in operating the window at very low temperatures: less absorption and consequent heating of the window, greater material strength, improved resistance to crack formation, greater thermal conductivity, and reduced thermal expansion. Operation at cryogenic temperatures is shown to be feasible. The output power, which is currently limited by window constraints, could be increased by an order of magnitude or more.

  9. Optic cavitation with CW lasers: A review

    NASA Astrophysics Data System (ADS)

    Padilla-Martinez, J. P.; Berrospe-Rodriguez, C.; Aguilar, G.; Ramirez-San-Juan, J. C.; Ramos-Garcia, R.

    2014-12-01

    The most common method to generate optic cavitation involves the focusing of short-pulsed lasers in a transparent liquid media. In this work, we review a novel method of optic cavitation that uses low power CW lasers incident in highly absorbing liquids. This novel method of cavitation is called thermocavitation. Light absorbed heats up the liquid beyond its boiling temperature (spinodal limit) in a time span of microseconds to milliseconds (depending on the optical intensity). Once the liquid is heated up to its spinodal limit (˜300 °C for pure water), the superheated water becomes unstable to random density fluctuations and an explosive phase transition to vapor takes place producing a fast-expanding vapor bubble. Eventually, the bubble collapses emitting a strong shock-wave. The bubble is always attached to the surface taking a semi-spherical shape, in contrast to that produced by pulsed lasers in transparent liquids, where the bubble is produced at the focal point. Using high speed video (105 frames/s), we study the bubble's dynamic behavior. Finally, we show that heat diffusion determines the water superheated volume and, therefore, the amplitude of the shock wave. A full experimental characterization of thermocavitation is described.

  10. Near Real-Time Gyrotron Data Streaming and Data Acquisition with ns Resolution on the DIII-D ECH System

    NASA Astrophysics Data System (ADS)

    Torrezan, A. C.; Ponce, D.; Gorelov, Y. A.; Cengher, M.; Lohr, J.

    2014-10-01

    As part of the expansion and upgrade of the electron cyclotron heating (ECH) systen on DIII-D, a new data acquisition setup has been implemented to acquire and display waveform data from all gyrotrons in near real time with high time resolution. The data acquisition for each gyrotron system is based on a fast digitizer with 8 channels running at 2 MS/s/channel and a resolution of 14 bits. This enables the operator to monitor all gyrotron-relevant variables as well as fast diagnostic signals such as window arcs. The data are transferred to a local computer through a 132 MB/s PCI bus, and then are streamed to the ECH operator and to a local network attached storage using 1 GB Ethernet links. The data are displayed to the ECH operator by means of a graphical user interface developed in LabVIEW, replacing physical scopes. Acquired gyrotron data are accessible at DIII-D through a local database (PTDATA) connected to the ECH data acquisition system by an Ethernet line, a configuration that eliminates the need for legacy CAMAC hardware in the data link. Work supported by the US Department of Energy under DE-FC02-04ER54698.

  11. Solid-state nitrogen-14 nuclear magnetic resonance enhanced by dynamic nuclear polarization using a gyrotron.

    PubMed

    Vitzthum, Veronika; Caporini, Marc A; Bodenhausen, Geoffrey

    2010-07-01

    By combining indirect detection of 14N with dynamic nuclear polarization (DNP) using a gyrotron, the signal-to-noise ratio can be dramatically improved and the recovery delay between subsequent experiments can be shortened. Spectra of glassy samples of the amino acid proline doped with the stable bi-radical TOTAPOL rotating at 15.625 kHz at 110K were obtained in a 400 MHz solid-state NMR spectrometer equipped with a gyrotron for microwave irradiation at 263 GHz. DNP enhancement factors on the order of epsilon approximately 40 were achieved. The recovery delays can be reduced from 60 s without radicals at 300 K to 6 s with radicals at 110 K. In the absence of radicals at room temperature, the proton relaxation in proline is inefficient due to the absence of rotating methyl groups and other heat sinks, thus making long recovery delays mandatory. DNP allows one to reduce the acquisition times of 13C-detected 14N spectra from several days to a few hours. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  12. Effect of ion compensation of the beam space charge on gyrotron operation

    SciTech Connect

    Fokin, A. P.; Glyavin, M. Yu.; Nusinovich, G. S.

    2015-04-15

    In gyrotrons, the coherent radiation of electromagnetic waves takes place when the cyclotron resonance condition between the wave frequency and the electron cyclotron frequency or its harmonic holds. The voltage depression caused by the beam space charge field changes the relativistic cyclotron frequency and, hence, can play an important role in the beam-wave interaction process. In long pulse and continuous-wave regimes, the beam space charge field can be partially compensated by the ions, which appear due to the beam impact ionization of neutral molecules of residual gases in the interaction space. In the present paper, the role of this ion compensation of the beam space charge on the interaction efficiency is analyzed. We also analyze the effect of the electron velocity spread on the limiting currents and discuss some effects restricting the ion-to-beam electron density ratio in the saturation stage. It is shown that the effect of the ion compensation on the voltage depression caused by the beam space charge field can cause significant changes in the efficiency of gyrotron operation and, in some cases, even result in the break of oscillations.

  13. High current multicharged metal ion source using high power gyrotron heating of vacuum arc plasma.

    PubMed

    Vodopyanov, A V; Golubev, S V; Khizhnyak, V I; Mansfeld, D A; Nikolaev, A G; Oks, E M; Savkin, K P; Vizir, A V; Yushkov, G Yu

    2008-02-01

    A high current, multi charged, metal ion source using electron heating of vacuum arc plasma by high power gyrotron radiation has been developed. The plasma is confined in a simple mirror trap with peak magnetic field in the plug up to 2.5 T, mirror ratio of 3-5, and length variable from 15 to 20 cm. Plasma formed by a cathodic vacuum arc is injected into the trap either (i) axially using a compact vacuum arc plasma gun located on axis outside the mirror trap region or (ii) radially using four plasma guns surrounding the trap at midplane. Microwave heating of the mirror-confined, vacuum arc plasma is accomplished by gyrotron microwave radiation of frequency 75 GHz, power up to 200 kW, and pulse duration up to 150 micros, leading to additional stripping of metal ions by electron impact. Pulsed beams of platinum ions with charge state up to 10+, a mean charge state over 6+, and total (all charge states) beam current of a few hundred milliamperes have been formed.

  14. Scattering volume in the collective Thomson scattering measurement using high power gyrotron in the LHD

    NASA Astrophysics Data System (ADS)

    Kubo, S.; Nishiura, M.; Tanaka, K.; Moseev, D.; Ogasawara, S.; Shimozuma, T.; Yoshimura, Y.; Igami, H.; Takahashi, H.; Tsujimura, T. I.; Makino, R.

    2016-06-01

    High-power gyrotrons prepared for the electron cyclotron heating at 77 GHz has been used for a collective Thomson scattering (CTS) study in LHD. Due to the difficulty in removing fundamental and/or second harmonic resonance in the viewing line of sight, the subtraction of the background ECE from measured signal was performed by modulating the probe beam power from a gyrotron. The separation of the scattering component from the background has been performed successfully taking into account the response time difference between both high-energy and bulk components. The other separation was attempted by fast scanning the viewing beam across the probing beam. It is found that the intensity of the scattered spectrum corresponding to the bulk and high energy components were almost proportional to the calculated scattering volume in the relatively low density region, while appreciable background scattered component remains even in the off volume in some high density cases. The ray-trace code TRAVIS is used to estimate the change in the scattering volume due to probing and receiving beam deflection effect.

  15. A broadband gyrotron backward-wave oscillator with tapered interaction structure and magnetic field

    SciTech Connect

    Li, G. D.; Chang, P. C.; Chiang, W. Y.; Lin, P. N.; Kao, S. H.; Lin, Y. N.; Huang, Y. J.; Barnett, L. R.; Chu, K. R.; Chen, H. Y.; Fan, C. T.

    2015-11-15

    The gyro-monotron and gyrotron backward-wave oscillator (gyro-BWO) are the two oscillator versions of gyrotrons. While serving different functions, they are also radically different in the RF field formation mechanisms. The gyro-monotron RF field profile is essentially fixed by the resonant interaction structure, while the gyro-BWO possesses an extra degree of freedom in that the axial RF field profile is self-determined by the beam-wave interaction in a waveguide structure. The present study examines ways to utilize the latter feature for bandwidth broadening with a tapered magnetic field, while also employing a tapered waveguide to enhance the interaction efficiency. We begin with a mode competition analysis, which suggests the theoretical feasibility of broadband frequency tuning in single-mode operation. It is then shown in theory that, by controlling the RF field profile with an up- or down-tapered magnetic field, the gyro-BWO is capable of efficient operation with a much improved tunable bandwidth.

  16. Operational Characteristics of a 14-W 140-GHz Gyrotron for Dynamic Nuclear Polarization

    PubMed Central

    Joye, Colin D.; Griffin, Robert G.; Hornstein, Melissa K.; Hu, Kan-Nian; Kreischer, Kenneth E.; Rosay, Melanie; Shapiro, Michael A.; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Woskov, Paul P.

    2006-01-01

    The operating characteristics of a 140-GHz 14-W long pulse gyrotron are presented. The device is being used in dynamic nuclear polarization enhanced nuclear magnetic resonance (DNP/NMR) spectroscopy experiments. The gyrotron yields 14 W peak power at 139.65 GHz from the TE(0,3) operating mode using a 12.3-kV 25-mA electron beam. Additionally, up to 12 W peak has been observed in the TE(2,3) mode at 136.90 GHz. A series of mode converters transform the TE(0,3) operating mode to the TE(1,1) mode. Experimental results are compared with nonlinear simulations and show reasonable agreement. The millimeter-wave output beam was imaged in a single shot using a pyroelectric camera. The mode patterns matched reasonably well to theory for both the TE(0,1) mode and the TE(1,1) mode. Repeatable mode patterns were obtained at intervals ranging from 0.8 s apart to 11 min apart at the output of the final mode converter. PMID:17431442

  17. Beam-wave interaction behavior of a 35 GHz metal PBG cavity gyrotron

    NASA Astrophysics Data System (ADS)

    Singh, Ashutosh; Jain, P. K.

    2014-09-01

    The RF behavior of a 35 GHz photonic band gap (PBG) cavity gyrotron operating in TE041-like mode has been presented to demonstrate its single mode operation capability. In this PBG cavity gyrotron, the conventional tapered cylindrical cavity is replaced by a metal PBG cavity as its RF interaction structure. The beam-wave interaction behavior has been explored using time dependent multimode nonlinear analysis as well as through 3D PIC simulation. Metal PBG cavity is treated here similar to that of a conventional cylindrical cavity for the desired mode confinement. The applied DC magnetic field profile has been considered uniform along the PBG cavity length both in analysis as well as in simulation. Electrons energy and phase along the interaction length of the PBG cavity facilitates bunching mechanism as well as energy transfer phenomena from the electron beam to the RF field. The RF output power for the TE041-like design mode as well as nearby competing modes have been estimated and found above to 100 kW in TE041-like mode with ˜15% efficiency. Results obtained from the analysis and the PIC simulation are found in agreement within 8% variation, and also it supports the single mode operation, as the PBG cavity does not switch into other parasitic modes in considerably large range of varying DC magnetic field, contrary to the conventional cylindrical cavity interaction structure.

  18. The 5.8 T Cryogen-Free Gyrotron Superconducting Magnet System on HL-2A

    NASA Astrophysics Data System (ADS)

    Xia, Donghui; Huang, Mei; Zhou, Jun; Bai, Xingyu; Zheng, Tieliu; Rao, Jun; Zhuang, Ge

    2014-04-01

    A 5.8 T cryogen-free superconducting magnet (SCM) system with a warm bore hole of 160 mm in diameter, used for gyrotrons operating in the frequency range from 68 GHz to 140 GHz, is installed on the site of the HL-2A tokamak. The SCM consists of two separate solenoidal magnetic coils connected in series, a 4.2 K Gifford-McMahon (GM) refrigerator, a compressor, a coil power supply and two temperature monitors. The performance, test and preliminary experimental results of this SCM system are described in this paper. The magnetic field distribution was measured along the axis, and a dummy tube was used for adjusting the magnet system. Finally, the magnet was used for the operation of a 68 GHz/500 kW gyrotron, which is part of an electron cyclotron resonance heating (ECRH) system. With an additional auxiliary coil and after adjusting the magnet system, a maximum output power for the ECRH system of up to 400 kW was achieved.

  19. Upgrade Of The TH1506B 118 GHz Gyrotron Using Modeing Tools

    SciTech Connect

    Darbos, C.; Bouquey, F.; Lambert, R.; Magne, R.; Traisnel, E.; Prinz, H. O.; Thumm, M.; Hogge, J. P.; Lievin, C.

    2007-09-28

    The first TH1506B prototype showing problems of overheating and spurious oscillations, a new modified gyrotron was built. During the tests, the extwo peaks, which was never predicted by simulations. Various low evel tests were performed on the mode converter with different shapes for the launcher but without real improvement. Besides measurements, the use of a new software Surf3D[l] showed that the problem mainly comes from the 3rd mirror whose curvature is too high and not well taken nto account by the calculation. This analysis software is based on ntegral equations and the complete 3D modelling alowed to determine a new profile for the 3rd mirror. An aluminium model of a new mirror was manufactured and thorough low level tests made at FZK showed that there was no double peak.The next step would consist in building a gyrotron based on this new design, to confirm the simulation and to valdate it for long pulses.

  20. Operational Characteristics of a 14-W 140-GHz Gyrotron for Dynamic Nuclear Polarization.

    PubMed

    Joye, Colin D; Griffin, Robert G; Hornstein, Melissa K; Hu, Kan-Nian; Kreischer, Kenneth E; Rosay, Melanie; Shapiro, Michael A; Sirigiri, Jagadishwar R; Temkin, Richard J; Woskov, Paul P

    2006-06-01

    The operating characteristics of a 140-GHz 14-W long pulse gyrotron are presented. The device is being used in dynamic nuclear polarization enhanced nuclear magnetic resonance (DNP/NMR) spectroscopy experiments. The gyrotron yields 14 W peak power at 139.65 GHz from the TE(0,3) operating mode using a 12.3-kV 25-mA electron beam. Additionally, up to 12 W peak has been observed in the TE(2,3) mode at 136.90 GHz. A series of mode converters transform the TE(0,3) operating mode to the TE(1,1) mode. Experimental results are compared with nonlinear simulations and show reasonable agreement. The millimeter-wave output beam was imaged in a single shot using a pyroelectric camera. The mode patterns matched reasonably well to theory for both the TE(0,1) mode and the TE(1,1) mode. Repeatable mode patterns were obtained at intervals ranging from 0.8 s apart to 11 min apart at the output of the final mode converter.

  1. Design of the Collective Thomson scattering (CTS) system by using 170-GHz gyrotron in the KSTAR

    NASA Astrophysics Data System (ADS)

    Park, Min; Kim, Sun-Ho; Kim, Sung-Kyu; Lee, Kyu-Dong; Wang, Son-Jong

    2014-10-01

    The physics of energetic ions is one of the primary subjects to be understood toward the realization of a nuclear fusion power plant. Collective Thomson scattering (CTS) offers the possibility to diagnose the fast ions and the alpha particles in burning plasmas. Spatially- and temporally-resolved one-dimensional velocity distributions of the fast ions can be obtained from the scattered radiation with fewer geometric constraints by utilizing millimeter waves from a high-power gyrotron as a probe beam. We studied the feasibility of CTS fast-ion measurements in the KSTAR by calculating the spectral density functions. Based on that, we suggest a design for the CTS system that uses the currently-operating 170-GHz gyrotron for electron cyclotron heating (ECH) and electron cyclotron current drive (ECCD) in the KSTAR. The CTS system is presented as two subsystems: the antenna system and the heterodyne receiver system. The design procedure for an off-axis ellipsoidal mirror is described, and the CTS system requirements are discussed.

  2. The NRL (Naval Research Laboratory) Phase-Locked gyrotron oscillator program for SDIO/IST

    NASA Astrophysics Data System (ADS)

    Manheimer, W. M.; Fliflet, A. W.; Gold, S. H.; Burke, J.; Black, W. M.; Barnett, L.

    1988-07-01

    This report is on the phase locked gyrotron oscillator program for SDIO/IST. The introduction summarizes the program as well as possible SDIO applications for high power phase locked microwave and millimeter wave sources. It considers the different possible architectures for a phased array for an SDIO mission. Section 2 summarizes results in theory. The main accomplishment was the development of a slow time scale code which examines phase locking in time varying situations. Section 3 summarizes the experimental design of the low power experiment which will examine phase locking in overmode cavities. Section 4 summarizes the results of the slotted cavity experiments. The axial slots allow for mode control. With a slotted cavity, a gyrotron oscillator has reliably generated 35 MW at 35 GHz in a standing TE Sub 13 mode. Section 5 summarizes results on the VEBA driven free running oscillator. This experiment has succeeded in generating 200 MW at 35 GHz in a TE sub 62 mode. Section 6 discusses experimental design of the VEBA fundamental mode three cavity phase-locked oscillator at 35 GHz. This experiment is expected to produce phase-locked power at the 5 MW level. Section 7 discusses the experimental results up to now on this experiment. Section 8 discusses the experimental design of the strongly coupled phase-locked oscillator experiment.

  3. Combined Hyperthermia and Photodynamic Therapy Using a Sub-THz Gyrotron as a Radiation Source

    NASA Astrophysics Data System (ADS)

    Miyoshi, Norio; Idehara, Toshitaka; Khutoryan, Eduard; Fukunaga, Yukihiro; Bibin, Andriana Bintang; Ito, Shinji; Sabchevski, Svilen Petrov

    2016-08-01

    In this paper, we present results of a hyperthermia treatment of malignant tumors using a gyrotron as a radiation source for heating of the cancerous tissue. They clearly demonstrate the efficiency of the irradiation by sub-THz waves, which leads to steady decrease of the volume of the tumor and finally to its disappearance. A combination of hyperthermia and photodynamic therapy (PDT) that utilizes a novel multifunctional photosensitizer has also been explored. In the latter case, the results are even more convincing and promising. In particular, while after a hyperthermia treatment sometimes a regrowth of the tumor is being observed, in the case of combined hyperthermia and PDT such regrowth has never been noticed. Another combined therapy is based on a preheating of the tumor by gyrotron radiation to temperatures lower than the hyperthermia temperature of 43 °C and followed then by PDT. The results show that such combination significantly increases the efficiency of the treatment. We consider this phenomenon as a synergy effect since it is absent when hyperthermia and PDT are applied separately, and manifests itself only when both methods are combined.

  4. Conceptual designs of E × B multistage depressed collectors for gyrotrons

    NASA Astrophysics Data System (ADS)

    Wu, Chuanren; Pagonakis, Ioannis Gr.; Gantenbein, Gerd; Illy, Stefan; Thumm, Manfred; Jelonnek, John

    2017-04-01

    Multistage depressed collectors are challenges for high-power, high-frequency fusion gyrotrons. Two concepts exist in the literature: (1) unwinding the spent electron beam cyclotron motion utilizing non-adiabatic transitions of magnetic fields and (2) sorting and collecting the electrons using the E × B drift. To facilitate the collection by the drift, the hollow electron beam can be transformed to one or more thin beams before applying the sorting. There are many approaches, which can transform the hollow electron beam to thin beams; among them, two approaches similar to the tilted electric field collectors of traveling wave tubes are conceptually studied in this paper: the first one transforms the hollow circular electron beam to an elongated elliptic beam, and then the thin elliptic beam is collected by the E × B drift; the second one splits an elliptic or a circular electron beam into two arc-shaped sheet beams; these two parts are collected individually. The functionality of these concepts is proven by CST simulations. A model of a three-stage collector for a 170 GHz, 1 MW gyrotron using the latter approach shows 76% collector efficiency while taking secondary electrons and realistic electron beam characteristics into account.

  5. Beam-wave interaction behavior of a 35 GHz metal PBG cavity gyrotron

    SciTech Connect

    Singh, Ashutosh; Jain, P. K.

    2014-09-15

    The RF behavior of a 35 GHz photonic band gap (PBG) cavity gyrotron operating in TE{sub 041}-like mode has been presented to demonstrate its single mode operation capability. In this PBG cavity gyrotron, the conventional tapered cylindrical cavity is replaced by a metal PBG cavity as its RF interaction structure. The beam-wave interaction behavior has been explored using time dependent multimode nonlinear analysis as well as through 3D PIC simulation. Metal PBG cavity is treated here similar to that of a conventional cylindrical cavity for the desired mode confinement. The applied DC magnetic field profile has been considered uniform along the PBG cavity length both in analysis as well as in simulation. Electrons energy and phase along the interaction length of the PBG cavity facilitates bunching mechanism as well as energy transfer phenomena from the electron beam to the RF field. The RF output power for the TE{sub 041}-like design mode as well as nearby competing modes have been estimated and found above to 100 kW in TE{sub 041}-like mode with ∼15% efficiency. Results obtained from the analysis and the PIC simulation are found in agreement within 8% variation, and also it supports the single mode operation, as the PBG cavity does not switch into other parasitic modes in considerably large range of varying DC magnetic field, contrary to the conventional cylindrical cavity interaction structure.

  6. High efficiency cw laser-pumped tunable alexandrite laser

    SciTech Connect

    Lai, S.T.; Shand, M.L.

    1983-10-01

    High efficiency cw alexandrite laser operation has been achieved. With longitudinal pumping by a krypton laser in a nearly concentric cavity, a 51% output power slope efficiency has been measured. Including the transmission at the input coupler mirror, a quantum yield of 85% has been attained above threshold. Tunability from 726 to 802 nm has also been demonstrated. The low loss and good thermal properties make alexandrite ideal for cw laser operation.

  7. High power CW iodine laser pumped by solar simulator

    NASA Technical Reports Server (NTRS)

    Lee, Ja H.; Lee, Min H.; Weaver, Willard R.

    1987-01-01

    An iodine photodissociation laser was pumped by a long Ar arc as the solar simulator to produce a 10-W CW output. Continuous lasing for 1 h was achieved with a flow of the laser material n-C3F7I. The 10-W CW output is the highest produced to date and establishes the feasibility of developing a solar-pumped laser for space power transmission.

  8. Design for a compact CW atom laser

    NASA Astrophysics Data System (ADS)

    Power, Erik; Raithel, Georg

    2011-05-01

    We present a design for a compact continuous-wave atom laser on a chip. A 2D spiral-shaped quadrupole guide is formed by two 0.5 mm × 0.5 mm wires carrying 5 A each embedded in a Si wafer; a 1.5 mm × 0.5 mm wire on the bottom layer carries -10 A, producing a horizontal B-field that pushes the guiding channel center above the chip surface. The center-to-center separation between the top wires is varied from 1.6 mm at the start of the guide to 1 mm at the end, decreasing the guide height from ~ 500 μm to ~ 25 μm above the surface as the atoms travel the 70 cm-long guide. The magnetic gradient of the guiding channel gradually increases from ~ 100 G /cm to ~ 930 G /cm . These features result in continuous surface adsorption evaporative cooling and progressive magnetic compression. Spin flip losses are mitigated by a solenoid sewn around the guide to produce a longitudinal B-field. 87Rb atoms are gravitationally loaded into the guide. A far off-resonant light shift barrier at the end of the guide traps the atoms and allows formation of a BEC. Tuning the barrier height to create a non-zero tunneling rate equal to the loading rate completes the implementation of a CW atom laser. Two options for atom interferometry are implemented on the first-generation chip (matter-wave Fabry-Perot interferometer and guide-based Mach-Zehnder interferometer). Current construction status and challenges will be discussed, along with preliminary results.

  9. 3 μm CW lasers for myringotomy and microsurgery.

    PubMed

    Linden, Kurt J; Pfeffer, Christian P; Sousa, John Gary; D'Alleva, Nicholas; Aslani, Arash; Gorski, Grzegorz; Kenna, Margaret; Poe, Dennis S

    2013-03-08

    This paper describes the development and implementation of 3 μm lasers for myringotomy and microsurgery. Two different lasers were investigated. The first, an Er-doped, CW zirconate glass fiber laser optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.76 μm with concomitant green incoherent emission that served as a convenient visible illumination beam. The second, a 1 W CW Er:YAG solid-state laser also optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.94 μm, coincident with the strongest infrared water absorption peak. Running CW, both lasers are expected to avoid the loud acoustical shocks associated with pulsed lasers. Myringotomies were carried out with the Er:YAG laser on anaesthetized guinea pigs and the effects of the laser were documented. Laser ablated samples of tympanic membrane, soft tissue and bone were histologically examined. Histology results indicated that the CW Er:YAG laser is a potential candidate for a new myringotomy tool and possibly for otologic microsurgery, but deliverable power levels need to be increased to the 2 W (or higher) level. This work was funded under NIH SBIR Grant No. 5R44DC004899.

  10. 3 μm CW lasers for myringotomy and microsurgery

    PubMed Central

    Linden, Kurt J.; Pfeffer, Christian P.; Sousa, John Gary; D’Alleva, Nicholas; Aslani, Arash; Gorski, Grzegorz; Kenna, Margaret; Poe, Dennis S.

    2013-01-01

    This paper describes the development and implementation of 3 μm lasers for myringotomy and microsurgery. Two different lasers were investigated. The first, an Er-doped, CW zirconate glass fiber laser optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.76 μm with concomitant green incoherent emission that served as a convenient visible illumination beam. The second, a 1 W CW Er:YAG solid-state laser also optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.94 μm, coincident with the strongest infrared water absorption peak. Running CW, both lasers are expected to avoid the loud acoustical shocks associated with pulsed lasers. Myringotomies were carried out with the Er:YAG laser on anaesthetized guinea pigs and the effects of the laser were documented. Laser ablated samples of tympanic membrane, soft tissue and bone were histologically examined. Histology results indicated that the CW Er:YAG laser is a potential candidate for a new myringotomy tool and possibly for otologic microsurgery, but deliverable power levels need to be increased to the 2 W (or higher) level. This work was funded under NIH SBIR Grant No. 5R44DC004899. PMID:24382990

  11. Optimization of terahertz range gyrotron self-excitation conditions by increasing the lifetime of cyclotron oscillators in low-voltage interaction space

    NASA Astrophysics Data System (ADS)

    Ginzburg, N. S.; Glyavin, M. Yu.; Zotova, I. V.; Zheleznov, I. V.; Fokin, A. P.

    2017-01-01

    We propose a method of reducing the starting and operating currents of short-wavelength gyrotrons that is based on the application of a decelerating voltage directly to the resonator. The desired effect is achieved due to increasing electron lifetime in the interaction space. At a preset injection current, this circumstance ensures gyrotron self-excitation at a relatively low diffraction Q-factor, which leads to significant reduction in ohmic losses.

  12. Spectra of low-frequency modulation of gyrotron radiation during electron-cyclotron resonance heating of plasma in the L-2M stellarator

    SciTech Connect

    Batanov, G. M.; Kolik, L. V.; Konchekov, E. M.; Malakhov, D. V.; Novozhilova, Yu. V.; Petelin, M. I.; Petrov, A. E.; Pshenichnikov, A. A.; Sarksyan, K. A.; Skvortsova, N. N.; Kharchev, N. K.

    2011-05-15

    Results from experimental studies of the modulation of the gyrotron power during electron cyclotron resonance heating of plasma L-2M stellarator are presented. It is shown that the modulation spectrum consists of separate spectral bands, among which a 20-kHz peak with a spectral density exceeding by one order of magnitude the spectral density of the other peaks is observed. This can be explained by the gyrotron operation being affected by the wave reflected from long-wavelength plasma fluctuations.

  13. Synthesis of Current-Voltage Characteristics of 670 GHz Gyrotron Magnetron Injection Gun and Calculation of the Helical Electron Beam Parameters at the Leading Edge of a High-Voltage Pulse

    NASA Astrophysics Data System (ADS)

    Manuilov, V. N.; Glyavin, M. Yu.

    2013-02-01

    A method of synthesis of current-voltage characteristics (CVC) and calculation of the parameters of a helical electron beam (HEB) at the leading edge of the accelerating voltage pulse for gyrotron electron guns is proposed. These data can be used for a study of the gyrotron startup scenario with the mode competition taken into account. As an example, the results of calculations for a pulsed gyrotron with a frequency of 670 GHz are presented.

  14. Comparative Pharmacodynamics of Pancuronium, Cisatracurium, and CW002 in Rabbits

    PubMed Central

    Diaz, Leslie L; Zhang, Jingwei; Heerdt, Paul M

    2014-01-01

    Pancuronium is a long-duration neuromuscular blocking drug (NMBD) that has been used in anesthetized rabbits at 0.1 mg/kg. However, there are limited data regarding the time course for recovery from this dose either spontaneously or with pharmacologic reversal. Here we defined the potency, onset, and recovery characteristics for the intermediate-duration NMBD cisatracurium and CW002 (a novel cysteine-inactivated molecule) in the rabbit, and test the hypothesis that these drugs may be alternatives to 0.1 mg/kg pancuronium for survival procedures. New Zealand white rabbits anesthetized with isoflurane were studied in a cross-over design. Potencies of cisatracurium and CW002 were defined as the effective dose for 95% depression of evoked muscle twitch (ED95). Responses to 3×ED95 were used to define onset (time to maximal effect), recovery index (RI; time from 25% to 75% recovery of twitch), and duration (time to complete recovery). Responses to all drugs were determined with and without reversal by neostigmine–glycopyrrolate or l-cysteine. CW002 was 4-fold more potent than was cisatracurium, but their onset, RI, and duration were similar. Pancuronium had similar onset and RI but longer duration, compared with cisatracurium and CW002. Reversal shortened the recovery index and duration for all 3 drugs. At 3×ED95, cisatracurium and CW002 had the same onset as did standard-dose pancuronium, but durations were shorter and more predictable. In addition, CW002 can be reversed without the potential side effects of cholinergic manipulation. We conclude that cisatracurium and CW002 are viable alternatives to pancuronium for survival studies in rabbits. PMID:24827571

  15. On the measurement of wind speeds in tornadoes with a portable CW/FM-CW Doppler radar

    SciTech Connect

    Bluestein, H.B. . School of Meteorology); Unruh, W.P. )

    1991-01-01

    Both the formation mechanism and structure of tornadoes are not yet well understood. The Doppler radar is probably the best remote-sensing instrument at present for determining the wind field in tornadoes. Although much has been learned about the non-supercell tornado from relatively close range using Doppler radars at fixed sites, close-range measurements in supercell tornadoes are relatively few. Doppler radar can increase significantly the number of high-resolution, sub-cloud base measurements of both the tornado vortex and its parent vortex in supercells, with simultaneous visual documentation. The design details and operation of the CW/FM-CW Doppler radar developed at the Los Alamos National Laboratory and used by storm-intercept teams at the Univ. of Oklahoma are described elsewhere. The radar transmits 1 W at 3 cm, and can be switched back and forth between CW and FM-CW modes. In the FM-CW mode the sweep repetition frequency is 15.575 kHz and the sweep width 1.9 MHz; the corresponding maximum unambiguous range and velocity, and range resolution are 5 km, {plus minus} 115 m s{sup {minus}1}, and 78 m respectively. The bistatic antennas, which have half-power beamwidths of 5{degree}, are easily pointed wit the aid of a boresighted VCR. FM-CW Data are recorded on the VCR, while voice documentation is recorded on the audio tape; video is recorded on another VCR. The radar and antennas are easily mounted on a tripod, and can be set up by three people in a minute or two. The purpose of this paper is to describe the signal processing techniques used to determine the Doppler spectrum in the FM-CW mode and a method of its interpretation in real time, and to present data gathered in a tornadic storm in 1990. 15 refs., 7 figs.

  16. Deevelopment of a 1.5 MW, 140 GHz coaxial gyrotron

    SciTech Connect

    Piosczyk, B.; Dammertz, G.; Iatrou, C.T.; Moebius, A.; Zhang, S.C.

    1995-12-31

    A 1.5 MW, 140 GHz, TE{sub 28,16}-coaxial gyrotron with an inverse MIG is under development. Preliminary rf-tests using an axial rf output and a simple cavity with a constant diameter and non-corrugated inner rod gave an rf output power of 1 MW with an efficiency of 23% at 140 GHz (TE{sub 28,16}) and 1.3 MW with an efficiency of 29% at 133 GHz (TE{sup 27,15}). No indications of beam instabilities in the beam tunnel between the IMIG gun and the cavity have been observed. Experiments with an improved cavity and the design of the tube with a radial dual Gaussian beam output and a depressed collector are underway.

  17. Experiments on a Ku-band gyrotron traveling-wave-tube amplifier with a tapered waveguide

    NASA Astrophysics Data System (ADS)

    Jung, Sang Wook; Lee, Han Seul; Jang, Kwang Ho; Choi, Jin Joo; So, Joon Ho

    2015-09-01

    A Ku-band gyrotron traveling-wave-tube (gyro-TWT) amplifier was investigated. To obtain a wide operating bandwidth, we used a two-stage tapered rectangular waveguide interaction circuit. An electron beam of 27 keV and 3.56 A was produced from a double-anode magnetron-injection-gun (MIG). The measured frequency bandwidth over 10 dB gain in the linear operation region was found to be 18%. The gyro-TWT's saturated output power was 14.9 kW at 14.4 GHz, corresponding to a saturated output power gain of 27.4 dB and an efficiency of 15.5%. The measured experimental results were in agreement with those of non-linear numerical simulations.

  18. Numerical Design of Megawatt Gyrotron with 120 GHz Frequency and 50% Efficiency for Plasma Fusion Application

    NASA Astrophysics Data System (ADS)

    Kumar, Nitin; Singh, Udaybir; Kumar, Anil; Bhattacharya, Ranajoy; Singh, T. P.; Sinha, A. K.

    2013-02-01

    The design of 120 GHz, 1 MW gyrotron for plasma fusion application is presented in this paper. The mode selection is carried out considering the aim of minimum mode competition, minimum cavity wall heating, etc. On the basis of the selected operating mode, the interaction cavity design and beam-wave interaction computation are carried out by using the PIC code. The design of triode type Magnetron Injection Gun (MIG) is also presented. Trajectory code EGUN, synthesis code MIGSYN and data analysis code MIGANS are used in the MIG designing. Further, the design of MIG is also validated by using the another trajectory code TRAK. The design results of beam dumping system (collector) and RF window are also presented. Depressed collector is designed to enhance the overall tube efficiency. The design study confirms >1 MW output power with tube efficiency around 50% (with collector efficiency).

  19. Design of a double-anode magnetron-injection gun for the W-band gyrotron

    NASA Astrophysics Data System (ADS)

    Jang, Kwang Ho; Choi, Jin Joo; So, Joon Ho

    2015-07-01

    A double-anode magnetron-injection gun (MIG) was designed. The MIG is for a W-band 10-kW gyrotron. Analytic equations based on adiabatic theory and angular momentum conservation were used to examine the initial design parameters such as the cathode angle, and the radius of the beam emitting surface. The MIG's performances were predicted by using an electron trajectory code, the EGUN code. The beam spread of the axial velocity, Δvz/vz, obtained from the EGUN code was observed to be 1.34% at α = 1.3. The cathode edge emission and the thermal effect were modeled. The cathode edge emission was found to have a major effect on the velocity spread. The electron beam's quality was significantly improved by affixing non-emissive cylinders to the cathode.

  20. Analytical theory of low-frequency space charge oscillations in gyrotrons

    SciTech Connect

    Yan Ran; Antonsen, T. M. Jr.; Nusinovich, G. S.

    2008-10-15

    Low-frequency oscillations attributed to reflected electrons bouncing adiabatically between the electron gun and the interaction space have been observed in many gyrotrons. An analytical model is considered which allows one to apply space-charge wave theory to the analysis of these oscillations. In the framework of the small-signal theory, the regions of low-frequency oscillations, the oscillation frequency and the temporal and spatial growth rates of low-frequency oscillations are determined in the relevant parameter space. The mode frequency is determined not only by the particle travel time, but by the travel time of charge waves on the reflected electron beam. This explains the existence of modes with noncommensurate frequencies.

  1. Magnetron injection gun for a broadband gyrotron backward-wave oscillator

    SciTech Connect

    Yuan, C. P.; Chang, T. H.; Chen, N. C.; Yeh, Y. S.

    2009-07-15

    The magnetron injection gun is capable of generating relativistic electron beam with high velocity ratio and low velocity spread for a gyrotron backward-wave oscillator (gyro-BWO). However, the velocity ratio ({alpha}) varies drastically against both the magnetic field and the beam voltage, which significantly limits the tuning bandwidth of a gyro-BWO. This study remedies this drawback by adding a variable trim field to adjust the magnetic compression ratio when changing the operating conditions. Theoretical results obtained by employing a two-dimensional electron gun code (EGUN) demonstrate a constant velocity ratio of 1.5 with a low axial velocity spread of 6% from 3.4-4.8 Tesla. These results are compared with a three-dimensional particle-tracing code (computer simulation technology, CST). The underlying physics for constant {alpha} will be discussed in depth.

  2. Computations of VSWR and mode conversion for complex gyrotron window geometries

    SciTech Connect

    Salop, A.; Caplan, M.

    1984-01-01

    A computational method is described for determining VSWR and mode conversion for complex gyrotron window geometries. Assuming symmetric TE/sub on/ modes propagating in a circular cross-section guide, containing the window, one can write the total solution to the wave equation as the sum of the incident wave plus a wave scattered from the dielectric window region. The equations can be reformulated in terms of the scattered wave, resulting in a Helmholtz wave equation with an inhomogeneous driving term corresponding to the polarization current of the dielectric. Solutions are obtained using a suitable modification of the wave equation solver OPNCAV, and reflection coefficients, VSWR's and mode conversion information are then derived from an analysis of the reflected and transmitted powers. VSWR computations for typical single- and double-disk windows agree with conventional impedance calculations to within about 1%. Results for more complicated curved-boundary windows which cannot be treated by the standard methods are discussed.

  3. Effects of pressure rise on cw laser ablation of tissue

    NASA Astrophysics Data System (ADS)

    LeCarpentier, Gerald L.; Motamedi, Massoud; Welch, Ashley J.

    1991-06-01

    The objectives of this research were to identify mechanisms responsible for the initiation of continuous wave (cw) laser ablation of tissue and investigate the role of pressure in the ablation process. Porcine aorta samples were irradiated in a chamber pressurized from 1 X 10-4 to 12 atmospheres absolute pressure. Acrylic and Zn-Se windows in the experimental pressure chamber allowed video and infrared cameras to simultaneously record mechanical and thermal events associated with cw argon laser ablation of these samples. Video and thermal images of tissue slabs documented the explosive nature of cw laser ablation of soft biological media and revealed similar ablation threshold temperatures and ablation onset times under different environmental pressures; however, more violent initiation explosions with decreasing environmental pressures were observed. These results suggest that ablation initiates with thermal alterations in the mechanical strength of the tissue and proceeds with an explosion induced by the presence superheated liquid within the tissue.

  4. Random FM-CW radar and its ECCM

    NASA Astrophysics Data System (ADS)

    Liu, Guosui; Shi, Xiangquan; Lu, Jinhui

    The principle of a random FM-CW radar system is introduced, and the range cutoff charactertistic (RCC) for the system is derived. In a fuze radar system, this radar can be used against passive jamming away from the point of range cutoff as well as against active jamming. Experimental results are presented which show that the random FM-CW radar system has RCC and ECCM properties. The system can be used as a short-range detection system, a low-altitude altimeter, and a blind landing device.

  5. SRF cavities for CW option of Project X Linac

    SciTech Connect

    Solyak, N.; Gonin, I.; Khabiboulline, T.; Lunin, A.; Perunov, N.; Yakovlev, V.; /Fermilab

    2009-09-01

    Alternative option of Project X is based on the CW SC 2GeV Linac with the average current 1mA. Possible option of the CW Linac considered in the paper includes low energy part consisted of a few families SC Spoke cavities (from 2.5 MeV to 466 MeV) and high energy part consisted of 2 types of elliptical cavities (v/c=0.81 and v/c=1). Requirements and designed parameters of cavities are considered.

  6. Time Shifted PN Codes for CW Lidar, Radar, and Sonar

    NASA Technical Reports Server (NTRS)

    Campbell, Joel F. (Inventor); Prasad, Narasimha S. (Inventor); Harrison, Fenton W. (Inventor); Flood, Michael A. (Inventor)

    2013-01-01

    A continuous wave Light Detection and Ranging (CW LiDAR) system utilizes two or more laser frequencies and time or range shifted pseudorandom noise (PN) codes to discriminate between the laser frequencies. The performance of these codes can be improved by subtracting out the bias before processing. The CW LiDAR system may be mounted to an artificial satellite orbiting the earth, and the relative strength of the return signal for each frequency can be utilized to determine the concentration of selected gases or other substances in the atmosphere.

  7. Experimental Study of a Gyrotron with a Sectioned Klystron-Type Cavity Operated at Higher Cyclotron Harmonics

    NASA Astrophysics Data System (ADS)

    Bandurkin, I. V.; Kalynov, Yu. K.; Savilov, A. V.

    2016-02-01

    We are planning to use extended cavities in order to excite gyrotrons with large electron orbits, which are operated at higher cyclotron harmonics in the terahertz frequency range. This is determined by both the weakness of the electron-wave interaction, and relatively low operating currents. Since the diffraction Q-factor of such cavities is high, a significant part of the highfrequency power produced by the electron beam is lost due to the ohmic loss in the cavity walls. As a way to solve this problem, we proposed a sectioned klystron-type cavity, where an extended length of the electron-wave interaction region can be combined with a relatively low diffraction Q-factor of the system. This work presents the results of the first experiment on a gyrotron with a sectioned cavity, where selective excitation of higher (second and third) cyclotron harmonics was observed in the terahertz frequency range (0 .55 and 0 .74 THz).

  8. Systematic cavity design approach for a multi-frequency gyrotron for DEMO and study of its RF behavior

    SciTech Connect

    Kalaria, P. C. Avramidis, K. A.; Franck, J.; Gantenbein, G.; Illy, S.; Pagonakis, I. Gr.; Thumm, M.; Jelonnek, J.

    2016-09-15

    High frequency (>230 GHz) megawatt-class gyrotrons are planned as RF sources for electron cyclotron resonance heating and current drive in DEMOnstration fusion power plants (DEMOs). In this paper, for the first time, a feasibility study of a 236 GHz DEMO gyrotron is presented by considering all relevant design goals and the possible technical limitations. A mode-selection procedure is proposed in order to satisfy the multi-frequency and frequency-step tunability requirements. An effective systematic design approach for the optimal design of a gradually tapered cavity is presented. The RF-behavior of the proposed cavity is verified rigorously, supporting 920 kW of stable output power with an interaction efficiency of 36% including the considerations of realistic beam parameters.

  9. Long-pulse operation of a 0.5 MW TE{sub 10.4} gyrotron at 140 GHz

    SciTech Connect

    Dammertz, G.; Iatrou, C.T.; Kuntze, M.; Moebius, A.; Piosczyk, B.; Braz, O.; Thumm, M. |

    1996-06-01

    Gyrotron oscillators have proven to be highly efficient sources of coherent mm-wave radiation. They have been used successfully for electron cyclotron resonance heating (ECRH) experiments and electron cyclotron diagnostics (ECD) of plasma fusion for some time. Due to the localized energy deposition, the temperature profile can be modified and the stability of the plasma can be improved. Here, the operation features of a TE{sub 10.4}-mode gyrotron oscillator with a quasi-optical mode converter and a single-stage depressed collector at 140 GHz with an output power of 500 kW in long pulses of 0.2 s are presented. Measurements on long-pulse operation of the tube are described in detail, and the significant differences between short- and long-pulse operation concerning efficiency and output power are pointed out. The variation of frequency during a pulse and an irreversible frequency shift during long-pulse operation were measured and are discussed with respect to gyrotron design.

  10. The Electron-Optical System of a Gyrotron with an Operating Frequency of 263 GHz for Spectroscopic Research

    NASA Astrophysics Data System (ADS)

    Kuftin, A. N.; Manuilov, V. N.

    2016-07-01

    We describe specific features of modeling numerically the operation of magnetron-injection guns, which form high-quality helical electron beams in gyrotrons operated in the short-wave part of the millimeter-wave band (at a wavelength of 1 mm). As an example, we consider the gun of a gyrotron having an operating frequency of 263 GHz designed for spectroscopic research. It is shown that there are good reasons to perform calculations and optimization of the magnetroninjection un in two steps. At the first step, a simplest two-dimensional model can be used, which allows only for the influence of the field of the electrodes and the intrinsic space charge of the beam on the beam parameters. At the second, final stage one should allow for such factors as roughness of the emitting surface and thermal velocities of electrons. The electron distribution function in oscillatory velocities and the coefficient of electron reflection from the magnetic mirror should be calculated. It is demonstrated that the magnetron-injection gun, which is optimized by the method presented, is sufficiently universal and can be operated both at the first and second cyclotron-frequency harmonics. This opens up the possibility of developing gyrotrons for spectroscopy applications at frequencies of 263 and 526 GHz, respectively, which are required for biological and medical research.

  11. Functional characterization of rice CW-domain containing zinc finger proteins involved in histone recognition.

    PubMed

    Zhang, Zhe; Zhang, Feng; Cheng, Zhi-Jun; Liu, Ling-Long; Lin, Qi-Bing; Wu, Fu-Qing; Zhang, Huan; Wang, Jiu-Lin; Wang, Jie; Guo, Xiu-Ping; Zhang, Xin; Lei, Cai-Lin; Zhao, Zhi-Chao; Zhu, Shan-Shan; Wan, Jian-Min

    2017-10-01

    Histone recognition is important for understanding the mechanisms of histone modification, which play a pivotal role in transcriptional regulation during plant development. Here, we identified three cysteine-tryptophan (CW)-domain containing zinc finger (ZF) proteins involved in histone recognition, namely OsCW-ZF3, OsCW-ZF5 and OsCW-ZF7. Protein sequence analysis showed that they have two unknown motifs in addition to the CW domain. All three OsCW-ZFs were expressed in aerial tissues, with relatively high levels in developing panicles. Subcellular localization revealed that the OsCW-ZFs target the cell nucleus and CW domains are not necessary for their nuclear localization. In contrast to OsCW-ZF3 and OsCW-ZF5 where the CW domains bind histone H3 lysine 4 with different methylated forms (H3K4me), the CW domain from OsCW-ZF7 recognizes only trimethylated histone H3 lysine 4 (H3K4me3). Analysis of mutant suggested that three conserved tryptophan residues in the CW domain are essential for binding to H3K4me. Further study found that OsCW-ZF7 interacts with TAFII20, a transcription initiation factor TFIID 20kDa subunit. Knockout of OsCW-ZF7 caused defective development of awns. This study provides new insights into our understanding of the CW domain and lays a foundation for further investigation of its roles in rice. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. CW-FIT: Group Contingency Effects across the Day

    ERIC Educational Resources Information Center

    Wills, Howard P.; Iwaszuk, Wendy M.; Kamps, Debra; Shumate, Emily

    2014-01-01

    This study explored the effects of a group-contingency intervention on student behavior across academic instructional periods. Research suggests group contingencies are evidence-based practices, yet calls for investigation to determine the best conditions and groups suited for this type of intervention. CW-FIT (Class-Wide Function-related…

  13. Passively mode-locked cw Coumarin 6 ring dye laser

    SciTech Connect

    French, P.M.W.; Opalinska, M.M.; Taylor, J.

    1989-02-15

    The passive mode locking of a cw Coumarin 6 dye laser in a colliding-pulse ring configuration is reported. Pulses of less than 500-fsec duration have been obtained from 518 to 554 nm, with the shortest pulses obtained being of 96-fsec duration.

  14. A wide-band Gunn-effect CW waveguide amplifier.

    NASA Technical Reports Server (NTRS)

    Sene, A.; Rosenbaum, F. J.

    1972-01-01

    Broad-band CW amplification with Gunn diodes in waveguide circuits has been obtained, with power gains typically between 10 and 15 dB and half-power bandwidths of more than 1 GHz. It is found that amplifier performance can be modeled with fair accuracy using a rough characterization for the diode parameters.

  15. Cascaded combiners for a high power CW fiber laser

    NASA Astrophysics Data System (ADS)

    Tan, Qirui; Ge, Tingwu; Zhang, Xuexia; Wang, Zhiyong

    2016-02-01

    We report cascaded combiners for a high power continuous wave (CW) fiber laser in this paper. The cascaded combiners are fabricated with an improved lateral splicing process. During the fusing process, there is no stress or tension between the pump fiber and the double-cladding fiber. Thus, the parameters of the combiner are better than those that have been reported. The coupling efficiency is 98.5%, and the signal insertion loss is 1%. The coupling efficiency of the cascaded combiners is 97.5%. The pump lights are individually coupled into the double-cladding fiber via five combiners. The thermal effects cannot cause damage to the combiners and the cascaded combiners can operate stably in high power CW fiber lasers. We also develop a high power CW fiber laser that generates a maximum 780 W of CW signal power at 1080 nm with 71% optical-to-optical conversion efficiency. The fiber laser is pumped via five intra-cavity cascaded combiners and five extra-cavity cascaded combiners with a maximum pump power of 1096 W and a pump wavelength of 975 nm.

  16. Nonlinear optical properties of methyl red under CW irradiation

    NASA Astrophysics Data System (ADS)

    Zheng, Yu; Ye, Qing; Wang, Chen; Wang, Jin; Deng, Zhichao; Mei, Jianchun; Zhou, Wenyuan; Zhang, Chunping; Tian, Jianguo

    2015-12-01

    Organic materials have wide potential application in nonlinear optical devices. The nonlinear optical (NLO) properties of methyl red (MR) doped polymethyl methacrylate (MR-PMMA) are investigated under CW laser irradiation at 473 nm, 532 nm and 632.8 nm, respectively. By combining Kramers-Kronig (K-K) relation and CW Z-scan technique, the effective refractive index n2 and the change of refractive index Δn are obtained under different scanning speed at 473 nm and 532 nm. Δn is positive at 473 nm, while Δn is negative at 532 nm. The experimental result is consistent with that of K-K relation. With the scanning speed decreasing, the NLO properties of MR-PMMA are enhanced. With different laser powers at 632.8 nm, MR-PMMA has only nonlinear absorption rather than nonlinear refraction. Meanwhile, the sample is investigated under pulse laser irradiation at 532 nm. Through the comparison of results of CW Z-scan and pulse Z-scan, the influence of the cumulative thermal effect on NLO properties of material is investigated. The results indicate that, under CW irradiation near the absorption peak wavelength, the cumulative thermal effect has great influence to the NLO properties of MR-PMMA.

  17. Quantum mechanical features of optically pumped CW FIR lasers

    NASA Technical Reports Server (NTRS)

    Seligson, D.; Leite, J. R. R.; Sanchez, A.; Feld, M. S.; Ducloy, M.

    1977-01-01

    Quantum mechanical predictions for the gain of an optically pumped CW FIR laser are presented for cases in which one or both of the pump and FIR transitions are pressure or Doppler broadened. The results are compared to those based on the rate equation model. Some of the quantum mechanical predictions are verified in CH3OH.

  18. Investigations of atmospheric dynamics using a CW Doppler sounder array

    NASA Technical Reports Server (NTRS)

    Rao, G. L.

    1974-01-01

    A three-dimensional CW Doppler sounding system currently under operation at the NASA-Marshall Space Flight Center, Alabama is described. The properties of the neutral atmosphere are discussed along with the theory of Doppler sounding technique. Methods of data analyses used to investigate the dynamical phenomena at the ionospheric heights are presented and suggestions for future investigations provided.

  19. Applications of KHZ-CW Lidar in Ecological Entomology

    NASA Astrophysics Data System (ADS)

    Malmqvist, Elin; Brydegaard, Mikkel

    2016-06-01

    The benefits of kHz lidar in ecological entomology are explained. Results from kHz-measurements on insects, carried out with a CW-lidar system, employing the Scheimpflug principle to obtain range resolution, are presented. A method to extract insect events and analyze the large amount of lidar data is also described.

  20. 60 GHz gyrotron development program. Quarterly report No. 5, July-September 1980

    SciTech Connect

    Shively, J.F.; Grant, T.J.; Nordquist, A.L.; Stone, D.S.; Wendell, G.E.

    1980-01-01

    The objective of this program is to develop a microwave oscillator capable of producing 200 kW of CW output power at 60 GHz. The use of cyclotron resonance interaction is being pursued. The design, procurement and early construction phases of this program are discussed.

  1. 60 GHz gyrotron development program. Quarterly report No. 4, April-June 1980

    SciTech Connect

    Shively, J.F.; Grant, T.J.; Stone, D.S.; Symons, R.S.; Wendell, G.E.

    1980-01-01

    The objective of this program is to develop a microwave oscillator capable of producing 200 kW of CW output power at 60 GHz. The use of cyclotron resonance interaction is being pursued. The design and early procurement and construction phases of this program are discussed.

  2. Theoretical study on mode competition between fundamental and second harmonic modes in a 0.42 THz gyrotron with gradually tapered complex cavity

    SciTech Connect

    Zhao, Qixiang Yu, Sheng; Zhang, Tianzhong; Li, Xiang

    2015-10-15

    In this paper, the nonlinear dynamics of mode competition in the complex cavity gyrotron are studied by using multi-frequency, time-dependent theory with the cold-cavity longitudinal profile approximation. Based on the theory, a code is written to simulate the mode competition in the gradually tapered complex cavity gyrotron operating at second harmonic oscillation. The simulations tracking seven competition modes show that single mode oscillation of the desired mode TE{sub 17.4} at 150 kW level can be expected with proper choice of operating parameters. Through studying on mode competition, it is proved that the complex cavity has a good capability for suppressing the mode competition. Meanwhile, it is found that TE{sub 17.3} could be excited in the first cavity as a competition mode when the gyrotron operating at large beam current, which leads to that TE{sub 17.3} and TE{sub 17.4} with different frequencies can coexist stably in the complex cavity gyrotron with very close amplitudes. Thus, the complex cavity might be used for multi-frequency output gyrotron.

  3. PROSPECTS FOR A VERY HIGH POWER CW SRF LINAC

    SciTech Connect

    Robert Rimmer

    2010-06-01

    Steady development in SRF accelerator technology combined with the success of large scale installations such as CEBAF at Jefferson Laboratory and the SNS Linac at ORNL gives credibility to the concept of very high average power CW machines for light sources or Proton drivers. Such machines would be powerful tools for discovery science in themselves but could also pave the way to reliable cost effective drivers for such applications as neutrino factories, an energy-frontier muon collider, nuclear waste transmutation or accelerator driven subcritical reactors for energy production. In contrast to machines such as ILC that need maximum accelerating gradient, the challenges in these machines are mainly in efficiency, reliability, beam stability, beam loss and of course cost. In this paper the present state of the art is briefly reviewed and options for a multi-GeV, multi-MW CW linac are discussed.

  4. The eclipsing binary CW Eridani. [three-color photoelectric observation

    NASA Technical Reports Server (NTRS)

    Chen, K.-Y.

    1975-01-01

    Results of three-color photoelectric observations of CW Eridani are presented which were made with a 30-inch telescope over the three-year period from 1970 to 1973. The times of minima are computed, solutions of the light curves are obtained, and theoretical light curves are computed from the solutions. The period is determined to be 2.72837 days, and the orbital and photoelectric elements are derived from solutions based on the idealized Russell model.

  5. Laser Photon Force Measurements using a CW Laser

    NASA Technical Reports Server (NTRS)

    Gray, Perry; Edwards, David L.; Carruth, M. Ralph, Jr.; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    The photon force resulting from the non-damaging impact of laser derived photons on a metallic target was measured using a vacuum compatible microbalance. This experiment quantitatively verified that the force resulting from laser photons impacting a reflective surface is measurable and predictable. The photon wavelength is 1064 mn and the laser is a multi-mode 30OW Nd YAG continuous wave (CW) laser.

  6. Inhomogeneous broadening effects in multimode CW chemical lasers

    NASA Astrophysics Data System (ADS)

    Mirels, H.

    1981-01-01

    The performance of a multiple longitudinal mode CW chemical laser is investigated with reference to the effects of inhomogeneous broadening for the case where the longitudinal mode spacing is small compared with the characteristic Doppler and homogeneous widths of the lasing medium. Both a Fabry-Perot resonator and a saturated amplifier are considered, using a two-vibrational-level model. Closed form solutions are obtained which are shown to be in good agreement with the numerical results of Bullock and Lipkis (1979).

  7. Centered CW interference rejection using spread spectrum techniques

    NASA Technical Reports Server (NTRS)

    Scholtz, R. A.

    1980-01-01

    A mathematical model is developed for the rejection of CW interference by spread spectrum techniques. When this interference is known to be exactly at the carrier frequency of the spread spectrum signal, this information can be used to design optimal IF filtering prior to despreading. The application of this approach to the pilot beam receiver of the Solar Power Satellite is considered as an example.

  8. All-PM CW fiber optical parametric oscillator.

    PubMed

    Zlobina, Ekaterina A; Kablukov, Sergey I; Babin, Sergey A

    2016-10-31

    We demonstrate for the first time a CW all-polarization maintaining (PM) all-fiber optical parametric oscillator (FOPO) based on a birefringent photonic crystal fiber pumped by a tunable linearly polarized ytterbium-doped fiber laser. The all-PM FOPO features polarization-adjustment-free tunable operation in wavelength range from 920 to 1000 nm for both the slow and the fast fiber axes with output power reaching 1.3 W.

  9. Scattering of a CW plane wave by a pulse

    NASA Astrophysics Data System (ADS)

    Trivett, D. H.; Rogers, P. H.

    1982-05-01

    A procedure similar to the CW crossed-beam calculation of Ingard and Pridmore-Brown (1956) is used to calculate the far field scattered sound pressure of a pulse interacting with a plane wave. The scattered sound is found to be at neither the sum nor the difference frequency. It is suggested that this type of interaction is ideal for investigating the scattering of sound by sound, and a numerical solution is used to discuss the general features of the nearfield waveform.

  10. Observation of cw squeezed light at 1550 nm.

    PubMed

    Mehmet, Moritz; Steinlechner, Sebastian; Eberle, Tobias; Vahlbruch, Henning; Thüring, André; Danzmann, Karsten; Schnabel, Roman

    2009-04-01

    We report on the generation of cw squeezed vacuum states of light at the telecommunication wavelength of 1550 nm. The squeezed vacuum states were produced by type I optical parametric amplification in a standing-wave cavity built around a periodically poled potassium titanyl phosphate crystal. A nonclassical noise reduction of 5.3 dB below the shot noise was observed by means of balanced homodyne detection.

  11. Quasi-cw 808-nm 300-W laser diode arrays

    NASA Astrophysics Data System (ADS)

    Bezotosnyi, V. V.; Kozyrev, A. A.; Kondakova, N. S.; Kondakov, S. A.; Krokhin, O. N.; Mikaelyan, G. T.; Oleshchenko, V. A.; Popov, Yu. M.; Cheshev, E. A.

    2017-02-01

    Samples of 808-nm quasi-cw laser diode arrays (LDAs) with an output power exceeding 300 W, a pulse duration of 200 μs, and a pulse repetition rate of 100 Hz are developed and fabricated. The main output parameters of a set of five LDAs, including light – current characteristics, current – voltage characteristics, and emission spectra are measured. Preliminary life tests show that the LDA power remains stable for 108 pulses.

  12. Translation of Toxicity Data into CW Agent Toxicity Estimates

    DTIC Science & Technology

    2003-07-01

    dosage defined by vapor concentration (C) multiplied by exposure time (T) CTXX -- Lethal or Effective Concentration-Time to XX% exposed Dependence of...kg, young healthy adult males Agents addressed: GA (tabun), GB (sarin), GD (soman), GF (cyclosarin), VX and HD (mustard) Routes of exposure ...use with CW agent exposure scenarios involving healthy adult males Evidence exists that in some mammalian species (ex. rodents) that a significant

  13. Low threshold CW Nc laser oscillator at 1060 nm study

    NASA Technical Reports Server (NTRS)

    Birnbaum, M.; Deshazer, L. G.

    1976-01-01

    A broad range of characteristics of neodymium/yag lasers were investigated. With Nd:YVO4 crystals, CW 1.06 mu lasers were operated with thresholds a factor of 2 lower than Nd:YAG and with greater slope efficiencies. Thus, the first step in the development of new oscillators suitable for application in high data rate laser communication systems which surpass the present performance of the Nd:YAG laser has been successfully demonstrated.

  14. Development of a cw Co : MgF 2 laser

    NASA Astrophysics Data System (ADS)

    Di Lieto, A.

    2003-03-01

    The results obtained in the development of a cryogenic cw Co : MgF 2 laser, realized at the Dipartimento di Fisica of the Università di Pisa are presented. The laser can be tuned continuously in the range between 1.6 and 2.1 μm, with a typical output power of 1-2 W. A preliminary application to the spectroscopy of a Tm : YLF doped crystal is reported by using a photoacoustic apparatus.

  15. Mechanisms of amplification of ultrashort electromagnetic pulses in gyrotron traveling wave tube with helically corrugated waveguide

    SciTech Connect

    Ginzburg, N. S. Zaslavsky, V. Yu.; Zotova, I. V.; Sergeev, A. S.; Zheleznov, I. V.; Samsonov, S. V.; Mishakin, S. V.

    2015-11-15

    A time-domain self consistent theory of a gyrotron traveling wave tube with a helically corrugated operating waveguide has been developed. Based on this model, the process of short pulse amplification was studied in regimes of grazing and intersection of the dispersion curves of the electromagnetic wave and the electron beam. In the first case, the possibility of amplification without pulse form distortion was demonstrated for the pulse spectrum width of the order of the gain bandwidth. In the second case, when the electrons' axial velocity was smaller than the wave's group velocity, it was shown that the slippage of the incident signal with respect to the electron beam provides feeding of the signal by “fresh” electrons without initial modulation. As a result, the amplitude of the output pulse can exceed the amplitude of its saturated value for the case of the grazing regime, and, for optimal parameters, the peak output power can be even larger than the kinetic power of the electron beam.

  16. G-band harmonic multiplying gyrotron traveling-wave amplifier with a mode-selective circuit

    SciTech Connect

    Yeh, Y. S.; Chen, Chang-Hong; Wang, Z. W.; Kao, B. H.; Chen, Chien-Hsiang; Lin, T. Y.; Guo, Y. W.

    2014-12-15

    Harmonic multiplying gyrotron traveling-wave amplifiers (gyro-TWAs) permit for magnetic field reduction and frequency multiplication. A high-order-mode harmonic multiplying gyro-TWA with large circuit dimensions and low ohmic loss can achieve a high average power. By amplifying a fundamental harmonic TE{sub 01} drive wave, the second harmonic component of the beam current initiates a TE{sub 02} wave to be amplified. Wall losses can suppress some competing modes because they act as an effective sink of the energy of the modes. However, such wall losses do not suppress all competing modes as the fields are contracted in the copper section in the gyro-TWA. An improved mode-selective circuit, using circular waveguides with the specified radii, can provide the rejection points within the frequency range to suppress the competing modes. The simulated results reveal that the mode-selective circuit can provide an attenuation of more than 10 dB to suppress the competing modes (TE{sub 21}, TE{sub 51}, TE{sub 22}, and TE{sub 03}). A G-band second harmonic multiplying gyro-TWA with the mode-selective circuit is predicted to yield a peak output power of 50 kW at 198.8 GHz, corresponding to a saturated gain of 55 dB at an interaction efficiency of 10%. The full width at half maximum bandwidth is 5 GHz.

  17. Low-voltage harmonic multiplying gyrotron traveling-wave amplifier in G band

    SciTech Connect

    Yeh, Y. S.; Guo, Y. W.; Kao, B. H.; Chen, C. H.; Wang, Z. W.; Hung, C. L.; Chang, T. H.

    2015-12-15

    Harmonic multiplying operation in a gyrotron traveling-wave amplifier (gyro-TWA) permits for magnetic field reduction and frequency multiplication. Lowering a beam voltage is an important step toward miniaturization of a harmonic multiplying gyro-TWA. However, the additional degree of freedom that is provided by the multitude cyclotron harmonics in a low-voltage harmonic multiplying gyro-TWA still easily generates various competing modes. An improved mode-selective circuit, using circular waveguides with various radii, can provide the rejection points within the frequency range to suppress competing modes. Simulated results reveal that the mode-selective circuit can provide an attenuation of more than 14 dB to suppress the competing modes. Furthermore, the performance of the gyro-TWA is analyzed for studying the sensitivity of the saturated output power and full width at half maximum bandwidth of the gyro-TWA to the beam voltage and the magnetic field. A stable low-voltage harmonic multiplying gyro-TWA with the mode-selective circuit is predicted to yield a peak output power of 24 kW at 200.4 GHz, corresponding to a saturated gain of 56 dB at an interaction efficiency of 20%. The full width at half maximum bandwidth is 3.0 GHz.

  18. Experimental results of the 140 GHz, 1 MW long-pulse gyrotron for W7-X

    NASA Astrophysics Data System (ADS)

    Koppenburg, K.; Arnold, A.; Borie, E.; Dammertz, G.; Giguet, E.; Heidinger, R.; Illy, S.; Kuntze, M.; Le Cloarec, G.; Legrand, F.; Leonhardt, W.; Lievin, C.; Neffe, G.; Piosczyk, B.; Schmid, M.; Thumm, M.

    2003-02-01

    Gyrotrons at high frequency with high output power are mainly developed for microwave heating and current drive in plasmas for thermonuclear fusion. For the stellarator Wendelstein 7-X now under construction at IPP Greifswald, Germany, a 10 MW ECRH system is foreseen. A 1 MW, 140 GHz long-pulse gyrotron has been designed and a pre-prototype (Maquette) has been constructed and tested in an European collaboration between FZK Karlsruhe, CRPP Lausanne, IPF Suttgart, IPP Greifswald, CEA Cadarache and TED Vélizy [1]. The cylindrical cavity is designed for operating in the TE28,8 mode. It is a standard tapered cavity with linear input downtaper and a non-linear uptaper. The diameter of the cylindrical part is 40.96 mm. The transitions between tapers and straight section are smoothly rounded to avoid mode conversion. The TE28,8-cavity mode is transformed to a Gaussian TEM0,0 output mode by a mode converter consisting of a rippled-wall waveguide launcher followed by a three mirror system. The output window uses a single, edge cooled CVD-diamond disk with an outer diameter of 106 mm, a window aperture of 88 mm and a thickness of 1.8 mm corresponding to four half wavelengths. The collector is at ground potential, and a depression voltage for energy recovery can be applied to the cavity and to the first two mirrors. Additional normal-conducting coils are employed to the collector in order to produce an axial magnetic field for sweeping the electron beam with a frequency of 7 Hz. A temperature limited magnetron injection gun without intermediate anode ( diode type ) is used. In short pulse operation at the design current of 40 A an output power of 1 MW could be achieved for an accelerating voltage of 82 kV without depression voltage and with a depression voltage of 25 kV an output power of 1.15 MW at an accelerating voltage of 84 kV has been measured. For these values an efficiency of 49% was obtained. At constant accelerating voltages, the output power did not change up to

  19. Design of 95 GHz gyrotron based on continuous operation copper solenoid with water cooling

    SciTech Connect

    Borodin, Dmitri; Ben-Moshe, Roey; Einat, Moshe

    2014-07-15

    The design work for 2nd harmonic 95 GHz, 50 kW gyrotron based on continuous operation copper solenoid is presented. Thermionic magnetron injection gun specifications were calculated according to the linear trade off equation, and simulated with CST program. Numerical code is used for cavity design using the non-uniform string equation as well as particle motion in the “cold” cavity field. The mode TE02 with low Ohmic losses in the cavity walls was chosen as the operating mode. The Solenoid is designed to induce magnetic field of 1.8 T over a length of 40 mm in the interaction region with homogeneity of ±0.34%. The solenoid has six concentric cylindrical segments (and two correction segments) of copper foil windings separated by water channels for cooling. The predicted temperature in continuous operation is below 93 °C. The parameters of the design together with simulation results of the electromagnetic cavity field, magnetic field, electron trajectories, and thermal analyses are presented.

  20. Stable harmonic multiplying gyrotron traveling-wave amplifier with distributed wall losses and attenuating severs

    SciTech Connect

    Yeh, Y. S.; Cheng, J. H.; Chen, L. K.; Hung, C. W.; Lo, C. Y.; Liao, C. W.

    2008-02-15

    Harmonic multiplying gyrotron traveling-wave amplifiers (gyro-TWTs) provide magnetic field reduction and frequency multiplication. However, spurious oscillations may reduce the amplification of the gyro-TWT. Most distributed-loss structures are stabilized in gyro-TWTs that operate at low beam currents. Attenuating severs are added to the interaction circuit of a distributed-loss gyro-TWT to prevent high beam currents that result in mode competition. This study proposes a Ka-band harmonic multiplying gyro-TWT, using distributed wall losses and attenuating severs, to improve the stability of the amplification and the performance of the amplifier. Simulation results reveal that the absolute instabilities are effectively suppressed by wall losses of the lossy and severed sections, especially in the low-k{sub z} and high-order modes. Meanwhile, the severed section, dividing an interaction circuit into several short sections, reduces the effective interaction lengths of the absolute instabilities. The stable harmonic multiplying gyro-TWT is predicted to yield a peak output power of 230 kW at 33.65 GHz with an efficiency of 30%, a saturated gain of 40 dB, and a 3 dB bandwidth of 0.8 GHz for a 60 kV, 13 A electron beam with an axial velocity spread of {delta}v{sub z}/v{sub z}=8%. The power/gain scaling and phase relation between the drive and the output waves are elucidated.

  1. Low-order-mode harmonic multiplying gyrotron traveling-wave amplifier in W band

    SciTech Connect

    Yeh, Y. S.; Chen, C. H.; Yang, S. J.; Lai, C. H.; Lin, T. Y.; Lo, Y. C.; Hong, J. W.; Hung, C. L.; Chang, T. H.

    2012-09-15

    Harmonic multiplying gyrotron traveling-wave amplifiers (gyro-TWAs) allow for magnetic field reduction and frequency multiplication. To avoid absolute instabilities, this work proposes a W-band harmonic multiplying gyro-TWA operating at low-order modes. By amplifying a fundamental harmonic TE{sub 11} drive wave, the second harmonic component of the beam current initiates a TE{sub 21} wave to be amplified. Absolute instabilities in the gyro-TWA are suppressed by shortening the interaction circuit and increasing wall losses. Simulation results reveal that compared with Ka-band gyro-TWTs, the lower wall losses effectively suppress absolute instabilities in the W-band gyro-TWA. However, a global reflective oscillation occurs as the wall losses decrease. Increasing the length or resistivity of the lossy section can reduce the feedback of the oscillation to stabilize the amplifier. The W-band harmonic multiplying gyro-TWA is predicted to yield a peak output power of 111 kW at 98 GHz with an efficiency of 25%, a saturated gain of 26 dB, and a bandwidth of 1.6 GHz for a 60 kV, 7.5 A electron beam with an axial velocity spread of 8%.

  2. Design of 95 GHz gyrotron based on continuous operation copper solenoid with water cooling.

    PubMed

    Borodin, Dmitri; Ben-Moshe, Roey; Einat, Moshe

    2014-07-01

    The design work for 2nd harmonic 95 GHz, 50 kW gyrotron based on continuous operation copper solenoid is presented. Thermionic magnetron injection gun specifications were calculated according to the linear trade off equation, and simulated with CST program. Numerical code is used for cavity design using the non-uniform string equation as well as particle motion in the "cold" cavity field. The mode TE02 with low Ohmic losses in the cavity walls was chosen as the operating mode. The Solenoid is designed to induce magnetic field of 1.8 T over a length of 40 mm in the interaction region with homogeneity of ±0.34%. The solenoid has six concentric cylindrical segments (and two correction segments) of copper foil windings separated by water channels for cooling. The predicted temperature in continuous operation is below 93 °C. The parameters of the design together with simulation results of the electromagnetic cavity field, magnetic field, electron trajectories, and thermal analyses are presented.

  3. Experimental investigation of a 140 GHz gyrotron-backward wave oscillator

    NASA Astrophysics Data System (ADS)

    Basten, M. A.; Guss, W. C.; Kreischer, K. E.; Temkin, R. T.; Caplan, M.

    1995-05-01

    We report the experimental operation of a voltage tunable gyrotron backward wave oscillator (gyro-BWO) in the frequency range near 140 GHz. Voltage tunability is an important feature of the gyro-BWO for application as a fast tuning source for driving high power free electron lasers or cyclotron autoresonance maser amplifiers. The gyro-BWO operated in an overmoded cylindrical waveguide structure in the TE1,2 mode. The electron beam source was a Pierce-wiggler gun producing an 80 kV, 6.2 A beam. Frequency tuning with voltage between 134 and 147 GHz was achieved in the TE1,2 mode with constant magnetic field. However, this tuning was found to be discontinuous. Output powers of up to 2 kW and 2% efficiency were found, significantly below theoretical predictions for a cold beam. The theoretical beam velocity spread was modeled by a 3D beam transport code. The code results show that space charge forces, coupled with the wiggler-induced helical motion and the short cyclotron wavelength of the beam, produce large increases in velocity spread in the magnetic compression region. A beam with smaller velocity spread would be needed to make the gyro-BWO operate at the desired efficiency.

  4. Harmonic mode competition in a terahertz gyrotron backward-wave oscillator

    SciTech Connect

    Kao, S. H.; Chiu, C. C.; Chang, P. C.; Wu, K. L.; Chu, K. R.

    2012-10-15

    Electron cyclotron maser interactions at terahertz (THz) frequencies require a high-order-mode structure to reduce the wall loss to a tolerable level. To generate THz radiation, it is also essential to employ cyclotron harmonic resonances to reduce the required magnetic field strength to a value within the capability of the superconducting magnets. However, much weaker harmonic interactions in a high-order-mode structure lead to serious mode competition problems. The current paper addresses harmonic mode competition in the gyrotron backward wave oscillator (gyro-BWO). We begin with a comparative study of the mode formation and oscillation thresholds in the gyro-BWO and gyromonotron. Differences in linear features result in far fewer 'windows' for harmonic operation of the gyro-BWO. Nonlinear consequences of these differences are examined in particle simulations of the multimode competition processes in the gyro-BWO, which shed light on the competition criteria between modes of different as well as the same cyclotron harmonic numbers. The viability of a harmonic gyro-BWO is assessed on the basis of the results obtained.

  5. Low-voltage harmonic multiplying gyrotron traveling-wave amplifier in G band

    NASA Astrophysics Data System (ADS)

    Yeh, Y. S.; Hung, C. L.; Chang, T. H.; Guo, Y. W.; Kao, B. H.; Chen, C. H.; Wang, Z. W.

    2015-12-01

    Harmonic multiplying operation in a gyrotron traveling-wave amplifier (gyro-TWA) permits for magnetic field reduction and frequency multiplication. Lowering a beam voltage is an important step toward miniaturization of a harmonic multiplying gyro-TWA. However, the additional degree of freedom that is provided by the multitude cyclotron harmonics in a low-voltage harmonic multiplying gyro-TWA still easily generates various competing modes. An improved mode-selective circuit, using circular waveguides with various radii, can provide the rejection points within the frequency range to suppress competing modes. Simulated results reveal that the mode-selective circuit can provide an attenuation of more than 14 dB to suppress the competing modes. Furthermore, the performance of the gyro-TWA is analyzed for studying the sensitivity of the saturated output power and full width at half maximum bandwidth of the gyro-TWA to the beam voltage and the magnetic field. A stable low-voltage harmonic multiplying gyro-TWA with the mode-selective circuit is predicted to yield a peak output power of 24 kW at 200.4 GHz, corresponding to a saturated gain of 56 dB at an interaction efficiency of 20%. The full width at half maximum bandwidth is 3.0 GHz.

  6. Design of a high voltage multi-cavity 35 GHz phase-locked gyrotron oscillator

    NASA Astrophysics Data System (ADS)

    1988-11-01

    This paper describes the design for an experimental high power, phase locked gyrotron oscillator. The electron beam is generated by a 1 MV pulseline accelerator, and the reference signal is provided by a 35 GHz, 20 kW magnetron. The expected output power is in the range of 1 to 10 MW. The design is based on a solid 1 MeV, 100 Amp, 4 mm electron beam with a momentum pitch ratio of 0.75. The locking signal from the magnetron is introduced via a prebunching cavity. A second (passive) bunching cavity is used to increase the locking frequency bandwidth obtainable with a given locking power. The bunching cavities are designed to operate in the fundamental TE 111 cylindrical cavity mode. Some competition from the TE 112 higher order axial mode could not be avoided due to the constraint on the minimum drift tube diameter set by the requirement to propagate the electron beam. The bunching cavities include two axial slots to control the cavity Q factor and suppress competing modes. Additional slots and apertures are used to suppress oscillation in the drift spaces. The output cavity operates in the TE sub 121 mode and is also slotted to reduce competing mode excitation. The maximum phase-locking bandwidth is estimated to be 0.1 percent and the time to achieve phase locked operation is about 20 nsec which is consistent with the pulselength of the NRL VEBA accelerator.

  7. Gyrotron-driven high current ECR ion source for boron-neutron capture therapy neutron generator

    NASA Astrophysics Data System (ADS)

    Skalyga, V.; Izotov, I.; Golubev, S.; Razin, S.; Sidorov, A.; Maslennikova, A.; Volovecky, A.; Kalvas, T.; Koivisto, H.; Tarvainen, O.

    2014-12-01

    Boron-neutron capture therapy (BNCT) is a perspective treatment method for radiation resistant tumors. Unfortunately its development is strongly held back by a several physical and medical problems. Neutron sources for BNCT currently are limited to nuclear reactors and accelerators. For wide spread of BNCT investigations more compact and cheap neutron source would be much more preferable. In present paper an approach for compact D-D neutron generator creation based on a high current ECR ion source is suggested. Results on dense proton beams production are presented. A possibility of ion beams formation with current density up to 600 mA/cm2 is demonstrated. Estimations based on obtained experimental results show that neutron target bombarded by such deuteron beams would theoretically yield a neutron flux density up to 6·1010 cm-2/s. Thus, neutron generator based on a high-current deuteron ECR source with a powerful plasma heating by gyrotron radiation could fulfill the BNCT requirements significantly lower price, smaller size and ease of operation in comparison with existing reactors and accelerators.

  8. Design of 95 GHz gyrotron based on continuous operation copper solenoid with water cooling

    NASA Astrophysics Data System (ADS)

    Borodin, Dmitri; Ben-Moshe, Roey; Einat, Moshe

    2014-07-01

    The design work for 2nd harmonic 95 GHz, 50 kW gyrotron based on continuous operation copper solenoid is presented. Thermionic magnetron injection gun specifications were calculated according to the linear trade off equation, and simulated with CST program. Numerical code is used for cavity design using the non-uniform string equation as well as particle motion in the "cold" cavity field. The mode TE02 with low Ohmic losses in the cavity walls was chosen as the operating mode. The Solenoid is designed to induce magnetic field of 1.8 T over a length of 40 mm in the interaction region with homogeneity of ±0.34%. The solenoid has six concentric cylindrical segments (and two correction segments) of copper foil windings separated by water channels for cooling. The predicted temperature in continuous operation is below 93 °C. The parameters of the design together with simulation results of the electromagnetic cavity field, magnetic field, electron trajectories, and thermal analyses are presented.

  9. A Variable Energy CW Compact Accelerator for Ion Cancer Therapy

    SciTech Connect

    Johnstone, Carol J.; Taylor, J.; Edgecock, R.; Schulte, R.

    2016-03-10

    Cancer is the second-largest cause of death in the U.S. and approximately two-thirds of all cancer patients will receive radiation therapy with the majority of the radiation treatments performed using x-rays produced by electron linacs. Charged particle beam radiation therapy, both protons and light ions, however, offers advantageous physical-dose distributions over conventional photon radiotherapy, and, for particles heavier than protons, a significant biological advantage. Despite recognition of potential advantages, there is almost no research activity in this field in the U.S. due to the lack of clinical accelerator facilities offering light ion therapy in the States. In January, 2013, a joint DOE/NCI workshop was convened to address the challenges of light ion therapy [1], inviting more than 60 experts from diverse fields related to radiation therapy. This paper reports on the conclusions of the workshop, then translates the clinical requirements into accelerat or and beam-delivery technical specifications. A comparison of available or feasible accelerator technologies is compared, including a new concept for a compact, CW, and variable energy light ion accelerator currently under development. This new light ion accelerator is based on advances in nonscaling Fixed-Field Alternating gradient (FFAG) accelerator design. The new design concepts combine isochronous orbits with long (up to 4m) straight sections in a compact racetrack format allowing inner circulating orbits to be energy selected for low-loss, CW extraction, effectively eliminating the high-loss energy degrader in conventional CW cyclotron designs.

  10. Neutron generator for BNCT based on high current ECR ion source with gyrotron plasma heating.

    PubMed

    Skalyga, V; Izotov, I; Golubev, S; Razin, S; Sidorov, A; Maslennikova, A; Volovecky, A; Kalvas, T; Koivisto, H; Tarvainen, O

    2015-12-01

    BNCT development nowadays is constrained by a progress in neutron sources design. Creation of a cheap and compact intense neutron source would significantly simplify trial treatments avoiding use of expensive and complicated nuclear reactors and accelerators. D-D or D-T neutron generator is one of alternative types of such sources for. A so-called high current quasi-gasdynamic ECR ion source with plasma heating by millimeter wave gyrotron radiation is suggested to be used in a scheme of D-D neutron generator in the present work. Ion source of that type was developed in the Institute of Applied Physics of Russian Academy of Sciences (Nizhny Novgorod, Russia). It can produce deuteron ion beams with current density up to 700-800 mA/cm(2). Generation of the neutron flux with density at the level of 7-8·10(10) s(-1) cm(-2) at the target surface could be obtained in case of TiD2 target bombardment with deuteron beam accelerated to 100 keV. Estimations show that it is enough for formation of epithermal neutron flux with density higher than 10(9) s(-1) cm(-2) suitable for BNCT. Important advantage of described approach is absence of Tritium in the scheme. First experiments performed in pulsed regime with 300 mA, 45 kV deuteron beam directed to D2O target demonstrated 10(9) s(-1) neutron flux. This value corresponds to theoretical estimations and proofs prospects of neutron generator development based on high current quasi-gasdynamic ECR ion source. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. First and second harmonic ECRH experience at gyrotron frequencies at LLNL

    SciTech Connect

    Stallard, B.

    1987-11-01

    Plasma heating of electrons in both mirror machines and tokamaks, using mm wave gyrotron sources, have been carried out in many experiments in recent years. The technology for both sources and mode-preserving waveguide transmission systems is well developed at power levels of 200 kW. At LLNL electron heating at 28 GHz in the TMX-U tandem mirror has been used to create hot electrons required for a thermal barrier (potential well). TMX-U, and other devices operating at lower frequency and power (10 GHz, few kW), routinely generates electron populations with mean energies of 100 to 500 keV and densities in the low to mid 10/sup 11/ cm/sup -3/ range. Radial pressure profiles vary from peaked-on-axis to hollow and are dependent on the mod-B resonance surfaces. Experiments on the axisymmetric mirror SM-1 have shown improved heating efficiency using multiple frequencies with narrow frequency separation. The importance of rf diffusion in determining electron confinement has been shown in CONSTANCE B. Fokker-Planck and particle orbit models have been useful for understanding the importance of cavity heating for creating runaway electrons, the sensitivity of hot electron production to cold plasma, the reduction of electron lifetime by rf diffusion, and the effect of multiple frequencies on heating stochasticity. Potential wells generated in plasmas with large fractions of mirror-trapped electrons have been measured in TMX-U. These offer prospects for enhanced confinement of highly stripped ions. 11 refs., 18 figs., 2 tabs.

  12. The novel HLA-Cw*1802 allele is associated with B*5703 in the Bubi population from Equatorial Guinea.

    PubMed

    Vilches, C; Bunce, M; de Pablo, R; Moreno, M E; Puente, S; Sanz, L; Kreisler, M

    1997-06-01

    The HLA-Cw*1801 specificity, a Cw7/Cw4 hybrid allele, has recently been described in association with B*8101 (formerly B"DT"). In this study, the new Cw*1802 variant, differing from Cw*1801 at exon 5, is found associated with B*5703 in Bubi individuals from Equatorial Guinea. Confirmatory complete coding regions of B*5703 and B*3910 are also reported.

  13. TWANG-PIC, a novel gyro-averaged one-dimensional particle-in-cell code for interpretation of gyrotron experiments

    SciTech Connect

    Braunmueller, F. Tran, T. M.; Alberti, S.; Genoud, J.; Hogge, J.-Ph.; Tran, M. Q.; Vuillemin, Q.

    2015-06-15

    A new gyrotron simulation code for simulating the beam-wave interaction using a monomode time-dependent self-consistent model is presented. The new code TWANG-PIC is derived from the trajectory-based code TWANG by describing the electron motion in a gyro-averaged one-dimensional Particle-In-Cell (PIC) approach. In comparison to common PIC-codes, it is distinguished by its computation speed, which makes its use in parameter scans and in experiment interpretation possible. A benchmark of the new code is presented as well as a comparative study between the two codes. This study shows that the inclusion of a time-dependence in the electron equations, as it is the case in the PIC-approach, is mandatory for simulating any kind of non-stationary oscillations in gyrotrons. Finally, the new code is compared with experimental results and some implications of the violated model assumptions in the TWANG code are disclosed for a gyrotron experiment in which non-stationary regimes have been observed and for a critical case that is of interest in high power gyrotron development.

  14. Mean time between failures (MTBF) and availability of the Gyrotron system used on the Microwave Tokamak Experiment at Lawrence Livermore National Laboratory

    SciTech Connect

    Ferguson, S.W.; Jackson, M.C.; Seilhymer, D.B.

    1993-09-03

    This paper presents an analysis of the mean time between failures (MTBF) and availability history of the Varian VGT8140, 400 Watt, 140 GHz Gyrotron that was operated on the Microwave Tokamak Experiment (MTX) at the Lawrence Livermore National Laboratory (LLNL).

  15. JLab CW Cryomodules for 4th Generation Light Sources

    SciTech Connect

    Rimmer, Robert; Bundy, Richard; Cheng, Guangfeng; Ciovati, Gianluigi; Clemens, William; Daly, Edward; Henry, James; Hicks, William; Kneisel, Peter; Manning, Stephen; Manus, Robert; Marhauser, Frank; Preble, Joseph; Reece, Charles; Smith, Karl; Stirbet, Mircea; Turlington, Larry; Wang, Haipeng; Wilson, Katherine

    2008-01-23

    Fourth generation light sources hold the prospect of unprecedented brightness and optical beam quality for a wide range of scientific applications. Many of the proposed new facilities will rely on large superconducting radio frequency (SRF) based linacs to provide high energy, low emittance CW electron beams. For high average power applications there is a growing acceptance of energy recovery linac (ERL) technology as the way to support large recirculating currents with modest RF power requirements. CW SRF and high current ERLs are two core competencies at Jefferson Lab. JLab has designed and built a number of CW cryomodules of several different types starting with the original CEBAF design, with variations for higher current in the two generations of JLab’s free-electron laser (FEL), through two intermediate prototypes to the final high-performance module for the 12 GeV upgrade. Each of these represent fully engineered and tested configurations with a variety of specifications that could be considered for possible use in fourth generation light sources. Furthermore JLab has been actively pursuing advanced concepts for highcurrent high-efficiency cryomodules for next generation ERL based FEL’s. These existing and proposed designs span the range from about 1mA single-pass to over 100 mA energy recovered current capability. Specialized configurations also exist for high-current non-energy recovered sections such as the injector region where very high RF power is required. We discuss the performance parameters of these existing and proposed designs and their suitability to different classes of fourth generation light sources.

  16. Statistical properties of partially coherent cw fiber lasers.

    PubMed

    Churkin, Dmitriy V; Smirnov, Sergey V; Podivilov, Evgenii V

    2010-10-01

    We perform a detailed quantitative numerical analysis of a partially coherent quasi-cw fiber laser on the example of a high-Q normal dispersion cavity Raman fiber laser. The key role of precise spectral performances of fiber Bragg gratings forming the laser cavity is clarified. It is shown that cross-phase modulation between the pump and Stokes waves does not affect the generation. Amplitudes of different longitudinal modes strongly fluctuate, obeying the Gaussian distribution. As the intensity statistics is noticeably nonexponential, longitudinal modes should be correlated.

  17. New frequency translation technique for FM-CW reflectometrya)

    NASA Astrophysics Data System (ADS)

    Meneses, Luis; Cupido, Luis; Manso, M. E.; Jet-Efda Contributors

    2010-10-01

    In broadband microwave reflectometry, coherent detection is widely used to obtain the phase information and to improve the systems sensitivity, both in diagnostics measuring the electronic density profile and plasma fluctuations. Coherent detection uses a translated version of the probing signal to guarantee a stable intermediate frequency. Here, a novel technique to generate the frequency translation by double frequency conversion is presented and its advantages over the commonly used single frequency conversion techniques employing image rejection mixers are discussed. The results obtained with the new frequency translator modules developed for the three JET FM-CW reflectometers, operating successfully at JET since mid-2009, are presented.

  18. Stable 1.25-W CW Methanol Laser

    NASA Technical Reports Server (NTRS)

    Farhoomand, Jam; Pickett, Herbert M.

    1989-01-01

    Far-infrared (FIR) laser operating at 119-micrometer-wavelength transition of methanol achieves very low drift in frequency. Continuous-wave (CW) FIR output is 1.25 W when laser pumped by 125-W commercial CO2 laser. Rate of drift of output frequency less than plus or minus 100 kHz per hour because laser designed to have low thermal-expansion coefficients and because temperatures of input and output couplers held within 0.1 degree C of fixed values.

  19. Quasi-CW Laser Diode Bar Life Tests

    NASA Technical Reports Server (NTRS)

    Stephen, Mark A.; Krainak, Michael A.; Dallas, Joseph L.

    1997-01-01

    NASA's Goddard Space Flight Center is developing technology for satellite-based, high peak power, LIDAR transmitters requiring 3-5 years of reliable operation. Semi-conductor laser diodes provide high efficiency pumping of solid state lasers with the promise of long-lived, reliable operation. 100-watt quasi- CW laser diode bars have been baselined for the next generation laser altimeters. Multi-billion shot lifetimes are required. The authors have monitored the performance of several diodes for billions of shots and investigated operational modes for improving diode lifetime.

  20. A CW radar for ranging with PN/PSK modulation

    NASA Astrophysics Data System (ADS)

    Knapp, W.; Waesserling, H. G.; Wigger, B.

    The design and performance of a compact CW spread-spectrum ranging radar with pseudonoise phase-shift-keying (PN/PSK) modulation are discussed. The operating principles of the SAW convolver employed for matched filtering (Grossl, 1985) are explained; the system configuration is illustrated with a block diagram; and performance data are summarized in a table. The radar provides range resolution 2 m out to a maximum range of 2.4 km. Operating parameters include code length 511 chirps, dynamic range 50 dB, pseudorandom-function repetition rate 31.9 MHz, processing time 16 microsec, and target recognition level above noise 38 dB.

  1. Design of 250-MW CW RF system for APT

    SciTech Connect

    Rees, D.

    1997-09-01

    The design for the RF systems for the APT (Accelerator Production of Tritium) proton linac will be presented. The linac produces a continuous beam power of 130 MW at 1300 MeV with the installed capability to produce up to a 170 MW beam at 1700 MeV. The linac is comprised of a 350 MHz RFQ to 7 MeV followed in sequence by a 700 MHz coupled-cavity drift tube linac, coupled-cavity linac, and superconducting (SC) linac to 1700 MeV. At the 1700 MeV, 100 mA level the linac requires 213 MW of continuous-wave (CW) RF power. This power will be supplied by klystrons with a nominal output power of 1.0 MW. 237 kystrons are required with all but three of these klystrons operating at 700 MHz. The klystron count includes redundancy provisions that will be described which allow the RF systems to meet an operational availability in excess of 95 percent. The approach to achieve this redundancy will be presented for both the normal conducting (NC) and SC accelerators. Because of the large amount of CW RF power required for the APT linac, efficiency is very important to minimize operating cost. Operation and the RF system design, including in-progress advanced technology developments which improve efficiency, will be discussed. RF system performance will also be predicted. Because of the simultaneous pressures to increase RF system reliability, reduce tunnel envelope, and minimize RF system cost, the design of the RF vacuum windows has become an important issue. The power from a klystron will be divided into four equal parts to minimize the stress on the RF vacuum windows. Even with this reduction, the RF power level at the window is at the upper boundary of the power levels employed at other CW accelerator facilities. The design of a 350 MHz, coaxial vacuum window will be presented as well as test results and high power conditioning profiles. The transmission of 950 kW, CW, power through this window has been demonstrated with only minimal high power conditioning.

  2. DC information preservation for cardiopulmonary monitor utilizing CW Doppler radar.

    PubMed

    Vergara, Alexander M; Boric-Lubecke, Olga; Lubecke, Victor M

    2008-01-01

    Direct conversion RF receivers introduce large DC offsets, reducing the dynamic range of the baseband signal. Coupled with the relatively small time varying signals in human vital sign monitoring using CW Doppler radar, extraction of cardio-pulmonary information becomes difficult. Previous DC offset compensation techniques utilizing AC coupling have proven detrimental to the performance of the system and the integrity of the low-frequency cardiopulmonary signals. A proposed system utilizing digitally controlled voltage feedback and center finding preserves the important DC information for optimal extraction of phase information in the quadrature system.

  3. High efficiency CW green-pumped alexandrite lasers

    NASA Astrophysics Data System (ADS)

    Kuper, J. W.; Brown, D. C.

    2006-02-01

    High power, CW and pulsed alexandrite lasers were produced by pumping the laser rod with a high quality diode pumped 532 nm laser sources. This pumping architecture provides stable performance with output power > 1.4 W at 767nm in the free running mode and 0.78W at 1000 Hz. An output of 80 mW at 375.5 nm was achieved at 500 Hz. This approach holds promise for the production of a scalable diode-pumped, tunable alexandrite laser systems operating in the near infrared (750 nm), and the ultraviolet (375 and 250 nm) spectral regions.

  4. Ultraviolet photometry of the eclipsing variable CW Cephei

    NASA Technical Reports Server (NTRS)

    Sobieski, S.

    1972-01-01

    An extended series of photometric observations were made of the eclipsing variable CW Cephei using the Wisconsin instrument on OAO-2. Approximate elements which were derived based solely on the eclipse depths and shape of the secondary are in satisfactory agreement with those found using ground based observations. However, persistent asymmetries and anomalous light variations, all larger than the expected experimental error, were also found; subsequent ground-based observations show H sub alpha entirely in emission indicating the presence of an extended gaseous system surrounding one or both of the components. Consistent solutions utilizing all data at all wavelengths were not found.

  5. Stable 1.25-W CW Methanol Laser

    NASA Technical Reports Server (NTRS)

    Farhoomand, Jam; Pickett, Herbert M.

    1989-01-01

    Far-infrared (FIR) laser operating at 119-micrometer-wavelength transition of methanol achieves very low drift in frequency. Continuous-wave (CW) FIR output is 1.25 W when laser pumped by 125-W commercial CO2 laser. Rate of drift of output frequency less than plus or minus 100 kHz per hour because laser designed to have low thermal-expansion coefficients and because temperatures of input and output couplers held within 0.1 degree C of fixed values.

  6. MMIC-calibrated probing by CW electrooptic modulation

    NASA Astrophysics Data System (ADS)

    Le Quang, D.; Erasme, Didier; Huyart, Bernard

    1995-05-01

    This paper describes an electrooptic probing technique using a cw semiconductor-laser beam associated with a fast photodetector. Besides its simplicity, this technique presents some advantages over the sampling one thanks to the presence of a Fabry-Perot effect, namely an enhancement of the electrooptic interaction and a simple solution to the calibration problem. The good validity of the calibration method allows the application of this technique to S-parameter measurements. The S-parameter determination, in modulus and in phase, of an industrial MMIC by the electrooptic method is reported and compared with direct network analyzer measurements.

  7. High-power pulsed gyrotron for 300 GHz-band collective Thomson scattering diagnostics in the Large Helical Device

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Yuusuke; Saito, Teruo; Tatematsu, Yoshinori; Ikeuchi, Shinji; Manuilov, Vladimir N.; Kasa, Jun; Kotera, Masaki; Idehara, Toshitaka; Kubo, Shin; Shimozuma, Takashi; Tanaka, Kenji; Nishiura, Masaki

    2015-01-01

    A high-power pulse gyrotron was developed to generate a probe wave for 300 GHz-band collective Thomson scattering (CTS) diagnostics in the Large Helical Device. In this frequency range, avoiding mode competition is critical to realizing high-power and stable oscillation with a narrow frequency bandwidth. A moderately over-moded cavity was investigated to ensure sufficient isolation of a desired mode from neighbouring modes, and to achieve high power output simultaneously. A cavity with the TE14,2 operation mode, a triode electron gun with an intense laminar electron beam, and an internal mode convertor were designed to construct a prototype tube. It was experimentally observed that oscillation of the TE14,2 mode was strong enough for mode competition, and provided high power with sufficient stability. The oscillation characteristics associated with the electron beam properties were compared with the numerical characteristics to find an optimum operating condition. As a result, single-mode operation with maximum output power of 246 kW was demonstrated at 294 GHz with 65 kV/14 A electron beam, yielding efficiency of ˜27%. The radiation pattern was confirmed to be highly Gaussian. The duration of the 130 kW pulse, which is presently limited by the power supply, was extended up to 30 µs. The experimental results validate our design concept and indicate the potential for realizing a gyrotron with higher power and longer pulse toward practical use in 300 GHz CTS diagnostics.

  8. The CW domain, a structural module shared amongst vertebrates, vertebrate-infecting parasites and higher plants.

    PubMed

    Perry, Jason; Zhao, Yunde

    2003-11-01

    A previously undetected domain, named CW for its conserved cysteine and tryptophan residues, appears to be a four-cysteine zinc-finger motif found exclusively in vertebrates, vertebrate-infecting parasites and higher plants. Of the twelve distinct nuclear protein families that comprise the CW domain-containing superfamily, only the microrchida (MORC) family has begun to be characterized. However, several families contain other domains suggesting a relationship between the CW domain and either chromatin methylation status or early embryonic development.

  9. Photometric analysis of the overcontact binary CW Cas

    SciTech Connect

    Wang, J. J.; Qian, S. B.; He, J. J.; Li, L. J.; Zhao, E. G.

    2014-11-01

    New CCD photometric observations of overcontact binary CW Cas were carried out in 2004 and 2011. In particular, the light curve obtained in 2004 shows a remarkable O'Connell effect. Compared with light curves in different observing seasons, variations were found. These variations can be explained by dark spot activities on the surface of at least one component. Using the Wilson-Devinney code with a spot model, we find that the photometric solutions confirm CW Cas is a shallow W-subtype overcontact binary with a spotted massive component. Our new determined times of minimum light together with the others published in the literature were analyzed to find a change of orbital period. From the O – C curves, the period of the system shows a cyclic period change (P {sub 3} = 69.9 yr, A {sub 3} = 0.03196 days) superposed on the linear increase. The cyclic variation, if explained as the light-travel time effect, reveals the presence of a tertiary companion.

  10. Optimizing Frequency-Modulated CW EDMR in silicon

    NASA Astrophysics Data System (ADS)

    Zhu, Lihuang; van Schooten, Kipp; Ramanathan, Chandrasekhar

    Electrically detected magnetic resonance (EDMR) is a powerful method of probing dopant and defect spin states in semiconductor devices. Moreover, at the single dopant level, these spin states are heavily investigated as potential qubit systems, though facile electronic access to single dopants is exceedingly difficult. We therefore characterize detection sensitivities of frequency-modulated CW-EDMR of phosphorus donors in silicon Si:P using a home-built 2.5 GHz system (~80 mT) at 5 K. An arbitrary waveform generator controls the frequency modulation, allowing us to optimize the signal to noise ratio (SNR) of both the dangling bond and phosphorus donor signals against multiple experimental parameters, such as modulation amplitude and modulation frequency. The optimal range of frequency modulation parameters is constrained by the relaxation time of the phosphorous electron at 5 K, resulting in the same sensitivity limit as field modulated CW-EDMR, but offers some technical advantages; e.g. reducing the relative contribution of magnetic field induced currents and eliminating the need for field modulation coils. We further characterize the EDMR SNR in Si:P as a function of optical excitation energy by using a narrow line laser, tunable across donor exciton and band gap states.

  11. Optimal Signal Processing of Frequency-Stepped CW Radar Data

    NASA Technical Reports Server (NTRS)

    Ybarra, Gary A.; Wu, Shawkang M.; Bilbro, Griff L.; Ardalan, Sasan H.; Hearn, Chase P.; Neece, Robert T.

    1995-01-01

    An optimal signal processing algorithm is derived for estimating the time delay and amplitude of each scatterer reflection using a frequency-stepped CW system. The channel is assumed to be composed of abrupt changes in the reflection coefficient profile. The optimization technique is intended to maximize the target range resolution achievable from any set of frequency-stepped CW radar measurements made in such an environment. The algorithm is composed of an iterative two-step procedure. First, the amplitudes of the echoes are optimized by solving an overdetermined least squares set of equations. Then, a nonlinear objective function is scanned in an organized fashion to find its global minimum. The result is a set of echo strengths and time delay estimates. Although this paper addresses the specific problem of resolving the time delay between the two echoes, the derivation is general in the number of echoes. Performance of the optimization approach is illustrated using measured data obtained from an HP-851O network analyzer. It is demonstrated that the optimization approach offers a significant resolution enhancement over the standard processing approach that employs an IFFT. Degradation in the performance of the algorithm due to suboptimal model order selection and the effects of additive white Gaussion noise are addressed.

  12. RF coupler for high-power CW FEL photoinjector

    SciTech Connect

    Kurennoy, S.; Young, L. M.

    2003-01-01

    A high-current emittance-compensated RF photoinjector is a key enabling technology for a high-power CW FEL. The design presently under way is a 100-mA 2.5-cell {pi}-mode, 700-MHz, normal conducting demonstration CW RF photoinjector. This photoinjector will be capable of accelerating 3 nC per bunch with an emittance at the wiggler less than 10 mm-mrad. The paper presents results for the RF coupling from ridged wave guides to hte photoinjector RF cavity. The LEDA and SNS couplers inspired this 'dog-bone' design. Electromagnetic modeling of the coupler-cavity system has been performed using both 2-D and 3-D frequency-domain calculations, and a novel time-domain approach with MicroWave Studio. These simulations were used to adjust the coupling coefficient and calculate the power-loss distribution on the coupling slot. The cooling of this slot is a rather challenging thermal management project.

  13. Optimal Signal Processing of Frequency-Stepped CW Radar Data

    NASA Technical Reports Server (NTRS)

    Ybarra, Gary A.; Wu, Shawkang M.; Bilbro, Griff L.; Ardalan, Sasan H.; Hearn, Chase P.; Neece, Robert T.

    1995-01-01

    An optimal signal processing algorithm is derived for estimating the time delay and amplitude of each scatterer reflection using a frequency-stepped CW system. The channel is assumed to be composed of abrupt changes in the reflection coefficient profile. The optimization technique is intended to maximize the target range resolution achievable from any set of frequency-stepped CW radar measurements made in such an environment. The algorithm is composed of an iterative two-step procedure. First, the amplitudes of the echoes are optimized by solving an overdetermined least squares set of equations. Then, a nonlinear objective function is scanned in an organized fashion to find its global minimum. The result is a set of echo strengths and time delay estimates. Although this paper addresses the specific problem of resolving the time delay between the first two echoes, the derivation is general in the number of echoes. Performance of the optimization approach is illustrated using measured data obtained from an HP-X510 network analyzer. It is demonstrated that the optimization approach offers a significant resolution enhancement over the standard processing approach that employs an IFFT. Degradation in the performance of the algorithm due to suboptimal model order selection and the effects of additive white Gaussion noise are addressed.

  14. Non-destructive sub-THz CW imaging

    NASA Astrophysics Data System (ADS)

    Karpowicz, Nicholas; Zhong, Hua; Xu, Jingzhou; Lin, Kuang-I.; Hwang, Jenn-Shyong; Zhang, Xi-Cheng

    2005-03-01

    A simple, compact CW sub-THz imaging system, utilizing a 0.2 and 0.6 THz Gunn diode source is presented. A silicon beam lead diode detector and a Golay cell are used for the detection. Various results are presented, which show that the CW THz imaging modality is suitable for diverse applications, such as non-destructive testing and security. The key components of the system include the Gunn diode assembly, an optical chopper, a polyethylene lens, a detector, a lock-in amplifier, and two translation stages. The beam from the Gunn diode is focused on the sample being imaged by the polyethylene lens, the transmitted or reflected beam is measured by the detector. The energy transmitted through the sample at each point in the plane of the sample is detected. Since the system has relatively few components compared to pulsed THz imaging systems, it is less expensive and easier to design and operate, although it does not provide depth or spectral information about the sample. Since no time-delay scans take place, scanning can be done quickly compared to a time-domain system, limited by the maximum velocity of the translation stages and response of the detectors. It provides information about the macroscopic features of hidden structures within materials that are transparent to sub THz radiation, such as space shuttle insulating foam, articles of clothing, and luggage.

  15. Structural rearrangements in the C/W(001) surface system

    SciTech Connect

    Lyman, P.F.; Mullins, D.R.

    1995-05-15

    We have investigated the surface structure of the C/W(001) surface system at submonolayer C coverages using Auger-electron spectroscopy and high-resolution core-level photoelectron spectroscopy. Core-level spectroscopy is a sensitive probe of an atom`s local electronic environment; by examining the core levels of the W atoms in the selvedge region, we monitored the response of the substrate to C adsorption. The average shift of the 4{ital f} core-level binding energy provided evidence for a heretofore unknown surface reconstruction that occurs upon submonolayer C adsorption. We also performed line-shape analysis on these core-level spectra, and have thereby elucidated the mechanism by which the low-coverage ({radical}2 {times} {radical}2 ){ital R}45{degree} structure evolves to a {ital c}(3 {radical}2 {times} {radical}2 ){ital R}45{degree} arrangement upon further C adsorption. The line-shape analysis also provides corroborating evidence for a proposed model of the saturated C/W(001)-(5{times}1) surface structure, and suggests that the first two or three atomic W layers are perturbed by the C adsorption and attendant reconstruction.

  16. Innovative high-power CW Yb:YAG cryogenic laser

    NASA Astrophysics Data System (ADS)

    Brown, D. C.; Singley, J. M.; Yager, E.; Kuper, J. W.; Lotito, B. J.; Bennett, L. L.

    2007-04-01

    In this paper we discuss a CW Yb:YAG cryogenic laser program that has resulted in the design and demonstration of a novel high power laser. Cryogenically-cooled crystalline solid-state lasers, and Yb:YAG lasers in particular, are attractive sources of scalable CW output power with very high wallplug efficiency and excellent beam-quality that is independent of the output power. This laser consists of a distributed array of seven highly-doped thin Yb:YAG-sapphire disks in a folded multiple-Z resonator. Individual disks are pumped from opposite sides using fiber-coupled ~ 30W 940nm pump diodes. The laser system we have constructed produces a near-diffraction-limited TEM 00 output beam with the aid of an active conduction-cooling design. In addition, the device can be scaled to very high average power in a MOPA configuration, by increasing the number and diameter of the thin disks, and by increasing the power of the pump diodes with only minor modifications to the current design. The thermal and optical benefits of cryogenically-cooled solid-state lasers will be reviewed, scalability of our Yb:YAG cryogenic laser design will be discussed, and we will present experimental results including output power, slope and optical-optical efficiencies, and beam-quality.

  17. Innovative high-power CW Yb:YAG cryogenic laser

    NASA Astrophysics Data System (ADS)

    Brown, D. C.; Singley, J. M.; Yager, E.; Kuper, J. W.; Lotito, B. J.; Bennett, L. L.

    2007-02-01

    In this paper we discuss a CW Yb:YAG cryogenic laser program that has resulted in the design and demonstration of a novel high power laser. Cryogenically-cooled crystalline solid-state lasers, and Yb:YAG lasers in particular, are attractive sources of scalable CW output power with very high wallplug efficiency and excellent beam-quality that is independent of the output power. This laser consists of a distributed array of seven highly-doped thin Yb:YAG-sapphire disks in a folded multiple-Z resonator. Individual disks are pumped from opposite sides using fiber-coupled ~ 30W 940nm pump diodes. The laser system we have constructed produces a near-diffraction-limited TEM 00 output beam with the aid of an active conduction-cooling design. In addition, the device can be scaled to very high average power in a MOPA configuration, by increasing the number and diameter of the thin disks, and by increasing the power of the pump diodes with only minor modifications to the current design. The thermal and optical benefits of cryogenically-cooled solid-state lasers will be reviewed, scalability of our Yb:YAG cryogenic laser design will be discussed, and we will present experimental results including output power, slope and optical-optical efficiencies, and beam-quality.

  18. An Acoustic Demonstration Model for CW and Pulsed Spectrosocopy Experiments

    NASA Astrophysics Data System (ADS)

    Starck, Torben; Mäder, Heinrich; Trueman, Trevor; Jäger, Wolfgang

    2009-06-01

    High school and undergraduate students have often difficulties if new concepts are introduced in their physics or chemistry lectures. Lecture demonstrations and references to more familiar analogues can be of great help to the students in such situations. We have developed an experimental setup to demonstrate the principles of cw absorption and pulsed excitation - emission spectroscopies, using acoustical analogues. Our radiation source is a speaker and the detector is a microphone, both controlled by a computer sound card. The acoustical setup is housed in a plexiglas box, which serves as a resonator. It turns out that beer glasses are suitable samples; this also helps to keep the students interested! The instrument is controlled by a LabView program. In a cw experiment, the sound frequency is swept through a certain frequency range and the microphone response is recorded simultaneously as function of frequency. A background signal without sample is recorded, and background subtraction yields the beer glass spectrum. In a pulsed experiment, a short sound pulse is generated and the microphone is used to record the resulting emission signal of the beer glass. A Fourier transformation of the time domain signal gives then the spectrum. We will discuss the experimental setup and show videos of the experiments.

  19. Slot-coupled CW standing wave accelerating cavity

    DOEpatents

    Wang, Shaoheng; Rimmer, Robert; Wang, Haipeng

    2017-05-16

    A slot-coupled CW standing wave multi-cell accelerating cavity. To achieve high efficiency graded beta acceleration, each cell in the multi-cell cavity may include different cell lengths. Alternatively, to achieve high efficiency with acceleration for particles with beta equal to 1, each cell in the multi-cell cavity may include the same cell design. Coupling between the cells is achieved with a plurality of axially aligned kidney-shaped slots on the wall between cells. The slot-coupling method makes the design very compact. The shape of the cell, including the slots and the cone, are optimized to maximize the power efficiency and minimize the peak power density on the surface. The slots are non-resonant, thereby enabling shorter slots and less power loss.

  20. Study of pseudo noise CW diode laser for ranging applications

    NASA Technical Reports Server (NTRS)

    Lee, Hyo S.; Ramaswami, Ravi

    1992-01-01

    A new Pseudo Random Noise (PN) modulated CW diode laser radar system is being developed for real time ranging of targets at both close and large distances (greater than 10 KM) to satisy a wide range of applications: from robotics to future space applications. Results from computer modeling and statistical analysis, along with some preliminary data obtained from a prototype system, are presented. The received signal is averaged for a short time to recover the target response function. It is found that even with uncooperative targets, based on the design parameters used (200-mW laser and 20-cm receiver), accurate ranging is possible up to about 15 KM, beyond which signal to noise ratio (SNR) becomes too small for real time analog detection.

  1. Autoconfocal microscopy with a cw laser and thermionic detection.

    PubMed

    Lim, Daryl; Chu, Kengyeh K; Mertz, Jerome

    2008-06-15

    We introduce an application of thermionic emission in a PMT photocathode. Because of the nonlinear dependence of thermionic emission on absorbed laser power, a conventional PMT is found to produce a virtual pinhole effect that rejects unfocused light at least as strongly as a physical pinhole. This virtual pinhole effect is exploited in a scanning transmission confocal microscope equipped with a cw laser source. Because the area of the PMT photocathode is large, signal descanning is not required and thermionic detection acts as a self-aligned pinhole. Our technique of thermionic-detection autoconfocal microscopy is further implemented with graded-field contrast to obtain enhanced phase-gradient sensitivity in unlabeled samples, such as rat hippocampal brain slices.

  2. Pulsed and CW performance of 7-stage interband cascade lasers.

    PubMed

    Canedy, Chadwick L; Abell, Joshua; Merritt, Charles D; Bewley, William W; Kim, Chul Soo; Kim, Mijin; Vurgaftman, Igor; Meyer, Jerry R

    2014-04-07

    We report a narrow-ridge interband cascade laser emitting at λ ≈3.5 μm that produces up to 592 mW of cw power with a wallplug efficiency of 10.1% and beam quality factor of M(2) = 3.7 at T = 25 °C. A pulsed cavity length study of broad-area lasers from the same wafer confirms that the 7-stage structure with thicker separate confinement layers has a reduced internal loss of ≈3 cm(-1). More generally, devices from a large number of wafers with similar 7-stage designs and wavelengths spanning 2.95-4.7 μm exhibit consistently higher pulsed external differential quantum efficiencies than earlier state-of-the-art ICLs.

  3. Parametric four-wave mixing using a single cw laser.

    PubMed

    Brekke, E; Alderson, L

    2013-06-15

    Four-wave mixing can be used to generate coherent output beams, with frequencies difficult to acquire in commercial lasers. Here, a single narrow external cavity diode laser locked to the two photon 5s-5d transition in rubidium is combined with a tapered amplifier system to produce a high power cw beam at 778 nm and used to generate coherent light at 420 nm through parametric four-wave mixing. This process is analyzed in terms of the intensity and frequency of the incoming beam as well as the atomic density of the sample. The efficiency of the process is currently limited when on resonance due to the absorption of the 420 nm beam, and modifications should allow a significant increase in output power.

  4. The 1.083 micron tunable CW semiconductor laser

    NASA Technical Reports Server (NTRS)

    Wang, C. S.; Chen, Jan-Shin; Lu, Ken-Gen; Ouyang, Keng

    1991-01-01

    A tunable CW laser is desired to produce light equivalent to the helium spectral line at 1.08 microns. This laser will serve as an optical pumping source for He-3 and He-4 atoms used in space magnetometers. This light source can be fabricated either as a semiconductor laser diode or a pumped solid state laser. Continuous output power of greater than 10 mW is desired. Semiconductor lasers can be thermally tuned, but must be capable of locking onto the helium resonance lines. Solid state lasers must have efficient pumping sources suitable for space configuration. Additional requirements are as follows: space magnetometer applications will include low mass (less than 0.5 kg), low power consumption (less than 0.75 W), and high stability/reliability for long missions (5-10 years).

  5. Operational experience with CW high gradient and high QL cryomodules

    SciTech Connect

    Hovater, J. Curt; Allison, Trent L.; Bachimanchi, Ramakrishna; Daly, Edward F.; Drury, Michael A.; Lahti, George E.; Mounts, Clyde I.; Nelson, Richard M.; Plawski, Tomasz E.

    2014-12-01

    The Continuous Electron Beam Accelerator Facility (CEBAF) energy upgrade from 6 GeV to 12 GeV includes the installation of ten new 100 MV cryomodules (80 cavities). The superconducting RF cavities are designed to operate CW at an accelerating gradient of 19.3 MV/m with a QL of 3×107. The RF system employs single cavity control using new digital LLRF controls and 13 kW klystrons. Recently, all of the new cryomodules and associated RF hardware and software have been commissioned and operated in the CEBAF accelerator. Electrons at linac currents up to 10 ?A have been successfully accelerated and used for nuclear physics experiments. This paper reports on the commissioning and operation of the cryomodules and RF system.

  6. Concepts for the JLab Ampere-Class CW Cryomodule

    SciTech Connect

    R. Rimmer; E.F. Daly; W.R. Hicks; J. Henry; J. Preble; M. Stirbet; H. Wang; K.M. Wilson; G. Wu

    2005-05-01

    We describe the concepts and developments underway at JLab as part of the program to develop a new CW cryomodule capable of transporting ampere-level beam currents in a compact FEL. Requirements include real-estate gradient of at least 10 MV/m and very strong HOM damping to push BBU thresholds up by two or more orders of magnitude compared to existing designs. Cavity shape, HOM damping, power couplers, tuners etc. are being designed and optimized for this application. Cavity considerations include a large iris for beam halo, low-RF losses, HOM frequencies and Q's, low peak surface fields, field flatness and microphonics. Module considerations include high packing factor, low static heat leak, image current heating of beam-line components, cost and maintainability. This module is being developed for the next generation ERL based high power FELs but may be useful for other applications such as electron cooling, electron-ion colliders, industrial processing etc.

  7. Low power cw-laser signatures on human skin

    SciTech Connect

    Lihachev, A; Lesinsh, J; Jakovels, D; Spigulis, J

    2011-01-24

    Impact of cw laser radiation on autofluorescence features of human skin is studied. Two methods of autofluorescence detection are applied: the spectral method with the use of a fibreoptic probe and spectrometer for determining the autofluorescence recovery kinetics at a fixed skin area of {approx}12 mm{sup 2}, and the multispectral visualisation method with the use of a multispectral imaging camera for visualising long-term autofluorescence changes in a skin area of {approx}4 cm{sup 2}. The autofluorescence recovery kinetics after preliminary laser irradiation is determined. Skin autofluorescence images with visible long-term changes - 'signatures' of low power laser treatment are acquired. (application of lasers and laser-optical methods in life sciences)

  8. Ultraviolet photometry of the eclipsing variable CW Cephei

    NASA Technical Reports Server (NTRS)

    Sobieski, S.

    1972-01-01

    A series of photometric observations was made of the eclipsing variable CW Cephei on the OAO 2. Approximate elements were derived from the eclipse depths and shape of the secondary. Persistent asymmetries and anomalous light variations, larger than the expected experimental error, were also found, subsequent ground-based observations show H alpha entirely in emission, indicating the presence of an extended gaseous system surrounding one or both components. A detailed comparison was made of the flux distribution of the binary relative to that for the nominally unreddened stars delta Pic, BlIII, and eta Aur, B3V, to investigate the effects of interstellar extinction. The resultant extinction curves, normalized at a wavelength of 3330 A, show a relatively smooth increase with decreasing wavelength.

  9. Characterization of a THz CW spectrometer pumped at 1550 nm

    NASA Astrophysics Data System (ADS)

    Yeo, Woon-Gi; Nahar, Niru K.

    2015-07-01

    We present an evaluation of a cost-effective THz CW spectrometer pumped at 1550 nm wavelengths with a fixed delay line. To study the spectral competence of the spectrometer, transmission data is obtained for various organic and inorganic samples. Spectral comparisons of the samples are presented by using THz time domain spectroscopy and vector network analyzer (VNA). Despite the capability of highly resolved transmission spectroscopy, our current system reveals the uncertainty in interferometric output data for phase analysis. Here, we identify the effect of fringing space of raw output data toward frequency resolution, phase analysis, and data acquisition time. We also propose the proper delay line setup for phase analysis for this type of spectrometers.

  10. High-power cw visible lasers pumped by Raman fibre lasers

    NASA Astrophysics Data System (ADS)

    Surin, A. A.; Larin, S. V.; Borisenko, T. E.; Prusakov, K. Yu.; Stirmanov, Yu. S.

    2016-12-01

    This paper describes cw visible lasers having an output power above 10 {\\text{W}} and emitting at wavelengths of 561, 589 and 623 {\\text{nm}}. An approach is proposed for obtaining single-mode cw visible laser light with a power above 10 {\\text{W}} at any wavelength in the range 560 - 660 {\\text{nm}}.

  11. Research on Doppler frequency in incoherent FM/CW laser detection

    NASA Astrophysics Data System (ADS)

    Liu, Kai; Cui, Zhanzhong

    2010-10-01

    The principle of transmitted and received laser in incoherent FM/CW laser detection is different from the one in coherent FM/CW laser detection. The methods for distance solution in both detections are similar. Incoherent FM/CW laser detection uses subcarrier to modulate the intensity of laser, and the photodetector detects the intensity of received signal. The amplified photocurrent is mixed with local oscillator signal, and the intermediate frequency (IF) signal contains the information of distance from sensor to target. The Doppler frequency for this detection is related with the relative radial velocity between sensor and target. The optical frequency is directly modulated with electro-optic device in coherent FM/CW laser detection and the received laser signal is photomixed with transmitted laser signal. The Doppler frequency in the detection relates to the optical frequency. In distance-measuring lidar, the Doppler frequency affects the solution. The Doppler frequency in incoherent FM/CW laser detection is unrelated with optical frequency, and it is much less than the one in coherent FM/CW laser detection, correspondingly. The error in incoherent FM/CW laser detection is smaller. As a result, the incoherent FM/CW laser detection is more suitable for the use of distance-measuring lidar.

  12. High-power pulsed and CW diode-pumped mode-locked Nd:YAG lasers

    NASA Technical Reports Server (NTRS)

    Marshall, Larry R.; Hays, A. D.; Kaz, Alex; Kasinski, Jeff; Burnham, R. L.

    1991-01-01

    The operation of both pulsed and CW diode-pumped mode-locked Nd:YAG lasers are presented. The pulsed laser produced 1.0 mJ with pulsewidths of 90 psec at 20 Hz. The CW pumped laser produced 6 W output at 1.064 microns and 3 W output at 532 nm.

  13. Three-dimensional simulation of triode-type MIG for 1 MW, 120 GHz gyrotron for ECRH applications

    NASA Astrophysics Data System (ADS)

    Singh, Udaybir; Kumar, Nitin; Kumar, Narendra; Kumar, Anil; Sinha, A. K.

    2012-01-01

    In this paper, the three-dimensional simulation of triode-type magnetron injection gun (MIG) for 120 GHz, 1 MW gyrotron is presented. The operating voltages of the modulating anode and the accelerating anode are 57 kV and 80 kV respectively. The high order TE 22,6 mode is selected as the operating mode and the electron beam is launched at the first radial maxima for the fundamental beam-mode operation. The initial design is obtained by using the in-house developed code MIGSYN. The numerical simulation is performed by using the commercially available code CST-Particle Studio (PS). The simulated results of MIG obtained by using CST-PS are validated with other simulation codes EGUN and TRAK, respectively. The results on the design output parameters obtained by using these three codes are found to be in close agreement.

  14. Status of Experiments on the EU 2 MW Coaxial Cavity Iter Gyrotron Pre-Prototype at Fzk

    NASA Astrophysics Data System (ADS)

    Kern, S.; Flamm, J.; Gantenbein, G.; Illy, S.; Jin, J.; Piosczyk, B.; Prinz, O.; Rzesnicki, T.; Thumm, M.; Dumbrajs, O.

    2009-04-01

    A coaxial cavity gyrotron, similar to the EU 2 MW tube for ITER, is under investigation at FZK at reduced magnetic field, which limits the expected RF power to 1.5 MW. While in former experiments only 1.1 MW was obtained, now, after the electron gun was changed, parasitic low frequency oscillations were removed and an RF power of 1.3 MW was reached. The power now seems to be limited by another parasitic high frequency oscillation at 160 GHz, which appears simultaneously to the desired working mode. A second problem of the pre-prototype tube, insufficient Gaussian mode content of the output wave of only 76%, was investigated by verifying the employed tools. The results indicate a problem at the third, phase correcting mirror, while the simulations appear to be acceptable. Finally, to further improve the quasi-optical mode converter a different approach to launcher design using arbitrary wall deformations is underway.

  15. Theoretical and experimental study of the space-charge oscillations in the electron-optical system of a relativistic gyrotron

    SciTech Connect

    Ilyakov, E. V. Kulagin, I. S.; Manuilov, V. N.; Movshevich, B. Z.

    2011-12-15

    A theoretical and experimental study of the oscillations of a space-charge cloud in a magnetron-injection gun of a powerful relativistic gyrotron has been performed. The charge storage occurs via electron-beam magnetic compression of the reflection of a part of the electrons having the highest transverse velocities from a magnetic mirror. It has been established that at high values of the compression coefficient the beam loses its stability that finally leads to the appearance of the beam current modulation at the frequency of the longitudinal oscillations of an electron beam in an adiabatic trap. According to the numerical simulations, the energy spread in the formed beam under these conditions reaches 4.6%, which is higher by an order of magnitude than that due to the space-charge effect in the beam transported along the metal tube.

  16. Radio-frequency plasma cleaning for mitigation of high-power microwave-pulse shortening in a coaxial gyrotron

    NASA Astrophysics Data System (ADS)

    Cohen, William E.; Gilgenbach, Ronald M.; Jaynes, Reginald L.; Peters, Christopher W.; Lopez, Mike R.; Lau, Y. Y.; Anderson, Scott A.; Brake, Mary L.; Spencer, Thomas A.

    2000-12-01

    Results are reported demonstrating that radio-frequency (rf) plasma cleaning is an effective technique for mitigating microwave-pulse shortening (i.e., lengthening the pulse) in a multimegawatt, large-orbit, coaxial gyrotron. Cleaning plasmas were generated by 50 W of rf power at 13.56 MHz in nitrogen fill gas in the pressure range 15-25 mTorr. Improvements in the averaged microwave energy output of this high-power-microwave device ranged from 15% to 245% for different initial conditions and cleaning protocols. The mechanism for this improvement is believed to be rf plasma sputtering of excess water vapor from the cavity/waveguide and subsequent removal of the contaminant by cryogenic vacuum pumps.

  17. Effects of tapering structures on the characteristics of a coaxial-waveguide gyrotron backward-wave oscillator

    SciTech Connect

    Hung, C. L.; Chang, T. H.; Yeh, Y. S.

    2011-10-15

    This study analyzes the characteristics of a gyrotron backward-wave oscillator (gyro-BWO) with a longitudinally tapered coaxial-waveguide by using a single-mode, self-consistent nonlinear code. Simulation results indicate that although tapering the inner wall or the outer wall can significantly raise the start-oscillation current, the former is more suitable for mode selection than the latter because an increase of the start-oscillation current by a tapered inner wall heavily depends on the chosen C value (i.e., the average ratio of the outer radius to the inner radius over the axial waveguide length). Selective suppression of the competing mode by tapering the inner wall is numerically demonstrated. Moreover, efficiency of the coaxial gyro-BWO is increased by tapering the outer wall. Properly down-tapering the outer wall ensures that the coaxial gyro-BWO can reach a maximum efficiency over twice that with a uniform one.

  18. Study on the After Cavity Interaction in a 140 GHz Gyrotron Using 3D CFDTD PIC Simulations

    NASA Astrophysics Data System (ADS)

    Lin, M. C.; Illy, S.; Avramidis, K.; Thumm, M.; Jelonnek, J.

    2016-10-01

    A computational study on after cavity interaction (ACI) in a 140 GHz gryotron for fusion research has been performed using a 3-D conformal finite-difference time-domain (CFDTD) particle-in-cell (PIC) method. The ACI, i.e. beam wave interaction in the non-linear uptaper after the cavity has attracted a lot of attention and been widely investigated in recent years. In a dynamic ACI, a TE mode is excited by the electron beam at the same frequency as in the cavity, and the same mode is also interacting with the spent electron beam at a different frequency in the non-linear uptaper after the cavity while in a static ACI, a mode interacts with the beam both at the cavity and at the uptaper, but at the same frequency. A previous study on the dynamic ACI on a 140 GHz gyrotron has concluded that more advanced numerical simulations such as particle-in-cell (PIC) modeling should be employed to study or confirm the dynamic ACI in addition to using trajectory codes. In this work, we use a 3-D full wave time domain simulation based on the CFDTD PIC method to include the rippled-wall launcher of the quasi-optical output coupler into the simulations which breaks the axial symmetry of the original model employing a symmetric one. A preliminary simulation result has confirmed the dynamic ACI effect in this 140 GHz gyrotron in good agreement with the former study. A realistic launcher will be included in the model for studying the dynamic ACI and compared with the homogenous one.

  19. Study on the Before Cavity Interaction in a Second Harmonic Gyrotron Using 3D CFDTD PIC Simulations

    NASA Astrophysics Data System (ADS)

    Lin, M. C.; Illy, S.; Thumm, M.; Jelonnek, J.

    2016-10-01

    A computational study on before cavity interaction (BCI) in a 28 GHz second harmonic (SH) gryotron for industrial applications has been performed using a 3-D conformal finite-difference time-domain (CFDTD) particle-in-cell (PIC) method. On the contrary to the after cavity interaction (ACI), i.e. beam wave interaction in the non-linear uptaper after the cavity, which has been widely investigated, the BCI, i.e. beam wave interaction in the non-linear downtaper before the cavity connected to the beam tunnel with an entrance, is less noticed and discussed. Usually the BCI might be considered easy to be eliminated. However, this is not always the case. As the SH gyrotron had been designed for SH TE12 mode operation, the first harmonic (FH) plays the main competition. In the 3-D CFDTD PIC simulations, a port boundary has been employed for the gyro-beam entrance of the gyrotron cavity instead of a metallic short one which is not reflecting a realistic situation as an FH backward wave oscillation (BWO) is competing with the desired SH generation. A numerical instability has been found and identified as a failure of the entrance port boundary caused by an evanescent wave or mode conversion. This indicates the entrance and downtaper are not fully cut-off for some oscillations. A further study shows that the undesired oscillation is the FH TE11 BWO mode concentrated around the beam tunnel entrance and downtaper. A mitigation strategy has been found to suppress this undesired BCI and avoid possible damage to the gun region.

  20. Retrograde regulation of nuclear gene expression in CW-CMS of rice.

    PubMed

    Fujii, Sota; Komatsu, Setsuko; Toriyama, Kinya

    2007-02-01

    The CW-cytoplasmic male sterility (CMS) line has the cytoplasm of Oryza rufipogon Griff, and mature pollen is morphologically normal under an optical microscope but lacks the ability to germinate; restorer gene Rf17 has been identified as restoring this ability. The difference between nuclear gene expression in mature anthers was compared for the CW-CMS line, [cms-CW] rf17rf17, and a maintainer line with normal cytoplasm of Oryza sativa L., [normal] rf17rf17. Using a 22-k rice oligoarray we detected 58 genes that were up-regulated more than threefold in the CW-CMS line. Expression in other organs was further investigated for 20 genes using RT-PCR. Five genes, including genes for alternative oxidase, were found to be preferentially expressed in [cms-CW] rf17rf17 but not in [normal] rf17rf17 or [cms-CW] Rf17Rf17. Such [cms-CW] rf17rf17-specific gene expression was only observed in mature anthers but not in leaves, stems, or roots, indicating the presence of anther-specific mitochondrial retrograde regulation of nuclear gene expression, and that Rf17 has a role in restoring the ectopic gene expression. We also used a proteomic approach to discover the retrograde regulated proteins and identified six proteins that were accumulated differently. These results reveal organ-specific induced mitochondrial retrograde pathways affecting nuclear gene expression possibly related to CMS.

  1. Suppression of spurious mode oscillation in mega-watt 77-GHz gyrotron as a high quality probe beam source for the collective Thomson scattering in LHD

    SciTech Connect

    Ogasawara, S.; Kubo, S.; Nishiura, M.; Tanaka, K.; Shimozuma, T.; Yoshimura, Y.; Igami, H.; Takahashi, H.; Ito, S.; Takita, Y.; Kobayashi, S.; Mizuno, Y.; Okada, K.; Tatematsu, Y.; Saito, T.; Minami, R.; Kariya, T.; Imai, T.

    2012-10-15

    Collective Thomson scattering (CTS) diagnostic requires a strong probing beam to diagnose a bulk and fast ion distribution function in fusion plasmas. A mega-watt gyrotron for electron cyclotron resonance heating is used as a probing beam in the large helical device. Spurious mode oscillations are often observed during the turning on/off phase of the modulation. The frequency spectra of the 77-GHz gyrotron output power have been measured, and then one of the spurious modes, which interferes with the CTS receiver system, is identified as the TE{sub 17,6} mode at the frequency of 74.7 GHz. The mode competition calculation indicates that the increase of the magnetic field strength at the gyrotron resonator can avoid such a spurious mode and excite only the main TE{sub 18,6} mode. The spurious radiation at the 74.7 GHz is experimentally demonstrated to be suppressed in the stronger magnetic field than that optimized for the high-power operation.

  2. Heterogeneously integrated 2.0 μm CW hybrid silicon lasers at room temperature.

    PubMed

    Spott, Alexander; Davenport, Michael; Peters, Jon; Bovington, Jock; Heck, Martijn J R; Stanton, Eric J; Vurgaftman, Igor; Meyer, Jerry; Bowers, John

    2015-04-01

    Here we experimentally demonstrate room temperature, continuous-wave (CW), 2.0 μm wavelength lasers heterogeneously integrated on silicon. Molecular wafer bonding of InP to Si is employed. These hybrid silicon lasers operate CW up to 35°C and emit up to 4.2 mW of single-facet CW power at room temperature. III-V tapers transfer light from a hybrid III-V/silicon optical mode into a Si waveguide mode. These lasers enable the realization of a number of sensing and detection applications in compact silicon photonic systems.

  3. Adapting TESLA technology for future cw light sources using HoBiCaT

    NASA Astrophysics Data System (ADS)

    Kugeler, O.; Neumann, A.; Anders, W.; Knobloch, J.

    2010-07-01

    The HoBiCaT facility has been set up and operated at the Helmholtz-Zentrum-Berlin and BESSY since 2005. Its purpose is testing superconducting cavities in cw mode of operation and it was successfully demonstrated that TESLA pulsed technology can be used for cw mode of operation with only minor changes. Issues that were addressed comprise of elevated dynamic thermal losses in the cavity walls, necessary modifications in the cryogenics and the cavity processing, the optimum choice of operational parameters such as cavity temperature or bandwidth, the characterization of higher order modes in the cavity, and the usability of existing tuners and couplers for cw.

  4. A Passively Q-Switched, CW-Pumped Fe:ZnSe Laser

    DTIC Science & Technology

    2014-03-01

    diode - pumped solid-state (DPSS) lasers [9] with a combined maximum pump power of 3 W at 2936 nm. This work used an X-shaped cavity design with an...600–606, Mar. 2012. [9] J. G. Sousa, D. Welford, and J. Foster, “Efficient 1.5 W CW and 7 mJ quasi-CW TEM00 mode operation of a compact diode - laser ...204 IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 50, NO. 3, MARCH 2014 A Passively Q-Switched, CW- Pumped Fe:ZnSe Laser Jonathan W. Evans, Patrick A

  5. Herschel PACS and SPIRE imaging of CW Leonis

    NASA Astrophysics Data System (ADS)

    Ladjal, D.; Barlow, M. J.; Groenewegen, M. A. T.; Ueta, T.; Blommaert, J. A. D. L.; Cohen, M.; Decin, L.; De Meester, W.; Exter, K.; Gear, W. K.; Gomez, H. L.; Hargrave, P. C.; Huygen, R.; Ivison, R. J.; Jean, C.; Kerschbaum, F.; Leeks, S. J.; Lim, T. L.; Olofsson, G.; Polehampton, E.; Posch, T.; Regibo, S.; Royer, P.; Sibthorpe, B.; Swinyard, B. M.; Vandenbussche, B.; Waelkens, C.; Wesson, R.

    2010-07-01

    Herschel PACS and SPIRE images have been obtained over a 30' × 30' area around the well-known carbon star CW Leo (IRC +10 216). An extended structure is found in an incomplete arc of 22' diameter, which is cospatial with the termination shock due to interaction with the interstellar medium (ISM) as defined by Sahai & Chronopoulos from ultraviolet GALEX images. Fluxes are derived in the 70, 160, 250, 350, and 550 μm bands in the region where the interaction with the ISM takes place, and this can be fitted with a modified black body with a temperature of 25 ± 3 K. Using the published proper motion and radial velocity for the star, we derive a heliocentric space motion of 25.1 km s-1. Using the PACS and SPIRE data and the analytical formula of the bow shock structure, we infer a de-projected standoff distance of the bow shock of R0 = (8.0 ± 0.3) × 1017 cm. We also derive a relative velocity of the star with respect to the ISM of (106.6 ± 8.7)/√{n_ISM} km s-1, where nISM is the number density of the local ISM. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  6. CW high intensity non-scaling FFAG proton drivers

    SciTech Connect

    Johnstone, C.; Berz, M.; Makino, K.; Snopok, P.; /IIT, Chicago

    2011-04-01

    Accelerators are playing increasingly important roles in basic science, technology, and medicine including nuclear power, industrial irradiation, material science, and neutrino production. Proton and light-ion accelerators in particular have many research, energy and medical applications, providing one of the most effective treatments for many types of cancer. Ultra high-intensity and high-energy (GeV) proton drivers are a critical technology for accelerator-driven sub-critical reactors (ADS) and many HEP programs (Muon Collider). These high-intensity GeV-range proton drivers are particularly challenging, encountering duty cycle and space-charge limits in the synchrotron and machine size concerns in the weaker-focusing cyclotrons; a 10-20 MW proton driver is not presently considered technically achievable with conventional re-circulating accelerators. One, as-yet, unexplored re-circulating accelerator, the Fixed-field Alternating Gradient, or FFAG, is an attractive alternative to the cyclotron. Its strong focusing optics are expected to mitigate space charge effects, and a recent innovation in design has coupled stable tunes with isochronous orbits, making the FFAG capable of fixed-frequency, CW acceleration, as in the classical cyclotron. This paper reports on these new advances in FFAG accelerator technology and references advanced modeling tools for fixed-field accelerators developed for and unique to the code COSY INFINITY.

  7. Spectral output from a premixed chain reaction cw HF laser

    SciTech Connect

    Stanton, A.C.; Bien, F.

    1980-07-01

    Spectral measurements of the output from a purely chemical chain reaction cw HF laser are reported. The laser is a subsonic H/sub 2/-F/sub 2/ flame, with supersonic premixing and spatially uniform initiation by a stationary normal shock. Initial chemical production of fluorine atoms is by the bimolecular reaction of F/sub 2/ with NO. Spectral measurements of the laser output near the initiating shock indicate lasing transitions in the P branches of the v=3 ..-->.. v=2, v=2 ..-->.. v=1, and v=1 ..-->.. v=0 HF bands. Further downstream, the upper vibrational levels are strongly deactivated, and lasing occurs only in the v=1 ..-->.. v=0 band. Laser emission in the v=2 ..-->.. v=1 band reappears at reduced NO flow rates, suggesting efficient deactivation of HF (v) by NO, possibly through multiquantum V-V exchange. An approximate rate of 5 x 10/sup -13plus-or-minus0.5/ cm/sup 3//sec for deactivation of HF (v=2) by NO is inferred.

  8. Linear and nonlinear analysis of a gyro-peniotron oscillator and study of start-up scenario in a high order mode gyrotron

    NASA Astrophysics Data System (ADS)

    Yeddulla, Muralidhar

    The Cyclotron Resonant Maser (CRM) is a device in which electrons gyrating in an external magnetic field produce coherent EM radiation. A DC electron beam current must be converted to an AC beam current to create RF energy. There are two possible approaches: phase bunching (O-type) and spatial segregation (M-type). In phase bunching, electrons are either accelerated or decelerated depending on when the electrons enter the interaction region, causing phase bunching. The electron bunches are then slowed down by the RF field for energy extraction. Not all electrons lose energy; some even gain energy. In spatial segregation, electrons entering the interaction region at different times are deflected in different directions. With an appropriate spatially varying RF field, all electrons can lose energy leading to very high conversion efficiency. A CRM with a smooth walled cylindrical waveguide interaction cavity and an annular electron beam passing through it can generate very large amount of RF energy. Depending on the electron beam position a gyrotron (O-type device) and a gyro-peniotron (M-type device) are possible. In this work, first, a nonlinear theory to study CRMs with a smooth walled cylindrical waveguide interaction cavity is presented. The nonlinear set of differential equations are linearized to study the starting conditions of the device. A gyro-peniotron operating in the TE0.2 -mode is studied using the theory presented. It is found that a gyro-peniotron operating in a low order mode can be self excited without mode competition from gyrotron modes, leading to the possibility of a very efficient high power RF source. A higher order mode gyro-peniotron experiences severe mode competition from gyrotron modes. The cavity Q required for gyro-peniotron operation is very high, which can lead to excessive heat in the cavity walls due to ohmic losses. Hence, a gyro-peniotron operation seems practical only in low order modes and in short pulses. Second, an existing

  9. Transpupillary CW YAG laser coagulation. A comparison with argon green and krypton red lasers.

    PubMed

    Peyman, G A; Conway, M D; House, B

    1983-08-01

    The authors have developed a CW YAG laser for transpupillary coagulation. The effects of CW YAG coagulation on the retina, retinal vessels, and fovea were compared with those produced by the krypton red and argon green lasers. To produce threshold coagulative lesions in monkeys and rabbits, we needed five to ten times more energy with the CW YAG than with the krypton red or argon green lasers. Nerve fiber damage was observed only when coagulating retinal vessels with the argon green laser. At the parameters used, none of the lasers damaged the sensory retina of the fovea. The CW YAG may be used as a new mode of laser coagulation in the treatment of retinal diseases.

  10. Interband cascade lasers with CW wallplug efficiency higher than 40% at low temperatures

    NASA Astrophysics Data System (ADS)

    Merritt, C. D.; Bewley, W. W.; Canedy, C. L.; Kim, C. S.; Kim, M.; Vurgaftman, I.; Meyer, J. R.

    2016-02-01

    We report cw wallplug efficiencies (WPEs) for mid-infrared interband cascade lasers (ICLs) that are comparable to those of state-of-the-art quantum cascade lasers at temperatures ranging from the cryogenic regime to room temperature. The continuous wave (cw) WPE for 10-stage broad-area devices remains above 40% for temperatures up to 125 K, and is still <30% at T = 175 K. At 80 K the threshold current density for a 2-mm-long cavity is only 11 A/cm2, and slope efficiencies are < 2.2 W/A at all temperatures <= 200 K. A 32-μm-wide × 3-mm-long ridge with 7 active stages and high-reflection and anti-reflection coatings on the two facets displays a cw WPE of 24% at T = 200 K and 12% at T = 300 K. The cw WPE of another narrow-ridge ICL was 18% at room temperature.

  11. The complete primary structure of Cw*1701 reveals a highly divergent HLA class I molecule.

    PubMed

    Herrero, M J; Vilches, C; de Pablo, R; Puente, S; Kreisler, M

    1997-03-01

    Genotyping of the HLA-C locus by PCR-SSP has previously shown 100% association of B41 and B42 with a new allelic variant. Partial sequencing studies (exons 2-4) demonstrated that this PCR-SSP variant corresponded to the new allele Cw*1701. In this study we have characterized the whole coding region of Cw*1701 from a Bubi individual of Equatorial Guinea. Our results partially confirm the previously reported sequence and reveal that Cw*1701 has many new polymorphisms at several exons, including a 18-bp insertion in exon 5. Cw*1701 is thus a most unusual HLA-C molecule defining a third allelic lineage of this locus.

  12. Reactions of CW Agents HD And GD with the Polymer Fabrics PVAM and CHEMCAT 41

    DTIC Science & Technology

    2015-09-01

    based catalysts for decontamination of HD and G agents,” Proceedings of the 2003 Joint Service Scientific Conference on Chemical & Biological...REACTIONS OF CW AGENTS HD AND GD WITH THE POLYMER FABRICS PVAM AND CHEMCAT 41   ECBC-TR-1311 David J. McGarvey RESEARCH AND TECHNOLOGY...2. REPORT TYPE Final 3. DATES COVERED (From - To) Aug 2011 - Nov 2014 4. TITLE AND SUBTITLE Reactions of CW Agents HD and GD with the Polymer

  13. A Plasma Initiation/Flow Chamber to Study CW Laser Beamed Energy Absorption in Light Gases.

    DTIC Science & Technology

    1984-03-01

    Induced Fluoresence ........................ 61 V) Future Work.......................................... 64VI) Appedixo........o...summarizes the work that has been accomplished to date and presents a schedule of future activity . S. - - * 4 II) Scientific Objectives Work on CW type...temperature plasma. Fowler used a 7 kW CW CO2 laser, focused by a 1 cm focal length mirror into a small high pressure cell (maximum pressure of 5 atm). The

  14. Effect of CW YAG and argon green lasers on experimentally detached retinas.

    PubMed

    Peyman, G A; Conway, M D; House, B J

    1984-06-01

    We evaluated the effects of argon-green (514.5 nm) and CW neodymium YAG (1060 nm) wavelengths on experimentally detached retinas of primates. Neither laser produced damage to the sensory retina of the fovea. The argon green wavelength, which was absorbed by haemoglobin in the vessel or by extravasated red blood cells, created vasospasm and nerve fiber layer damage. The beam of the CW YAG was not absorbed by haemoglobin; therefore, no vasospasm could be produced on experimentally detached retinas.

  15. Attogram measurement of rare isotopes by CW resonance ionization mass spectrometry

    SciTech Connect

    Bushaw, B.A.

    1992-05-01

    Three-color double-resonance ionization mass spectrometry, using two single-frequency cw dye lasers and a cw carbon dioxide laser, has been applied to the detection of attogram quantities of rare radionuclides. {sup 210}Pb has been measured in human hair and brain tissue samples to assess indoor radon exposure. Measurements on {sup 90}Sr have shown overall isotopic selectivity of greater than 10{sup 9} despite unfavorable isotope shifts relative to the major stable isotope, {sup 88}Sr.

  16. Attogram measurement of rare isotopes by CW resonance ionization mass spectrometry

    SciTech Connect

    Bushaw, B.A.

    1992-05-01

    Three-color double-resonance ionization mass spectrometry, using two single-frequency cw dye lasers and a cw carbon dioxide laser, has been applied to the detection of attogram quantities of rare radionuclides. {sup 210}Pb has been measured in human hair and brain tissue samples to assess indoor radon exposure. Measurements on {sup 90}Sr have shown overall isotopic selectivity of greater than 10{sup 9} despite unfavorable isotope shifts relative to the major stable isotope, {sup 88}Sr.

  17. Natural gas leaks detection by spatial-resolvable cw-laser-based remote monitoring

    NASA Astrophysics Data System (ADS)

    Agishev, Ravil R.; Bajazitov, Ravil A.; Galeyev, Marat M.; Ismagilov, Zufar B.

    1996-11-01

    The opportunities of spatial-resolvable atmosphere monitoring and atmospheric pollutions' remote chemical analysis based on the CW-laser radiants are investigated. A frequency-responsive processing peculiarities of atmosphere remote sensing signals are described. Application of the mentioned approach for the limited hydrocarbons remote detection and sensing is discussed. The requirements to the CW-LIDAR' receiving and radiating systems parameters are formulated. The evaluations of the system sensitivity limit, measurement accuracy and accuracy increase ways are presented.

  18. Spatial-resolvable remote sensing and detection of hydrocarbons based on cw low-power lasers

    NASA Astrophysics Data System (ADS)

    Agishev, Ravil R.; Bajazitov, Ravil A.; Galeyev, Marat M.

    1996-09-01

    The opportunities of spatial-resolvable atmosphere monitoring and atmospheric pollutions' remote chemical analysis based on the CW-laser radiants are investigated. A frequency-responsive processing peculiarities of atmosphere remote sensing signals are described. Application of the mentioned approach for the limited hydrocarbons remote detection and sensing is discussed. The requirements to the CW-LIDAR receiving and radiating systems parameters are formulated. The evaluations of the system sensitivity limit, measurement accuracy and accuracy increase ways are presented.

  19. Forensic Application of FM-CW and Pulse Radar

    SciTech Connect

    S. K. Koppenjan; R. S. Freeland; M. L. Miller; R. E. Yoder

    2003-01-01

    Ground-penetrating radar (GPR) technology has supplied vital assistance in criminal investigations. However, law enforcement personnel desire further developments such that the technology is rapidly deployable, and that it provides both a simple user interface and sophisticated target identification. To assist in the development of target identification algorithms, our efforts involve gathering background GPR data for the various site conditions and circumstances that often typify clandestine burials. For this study, forensic anthropologists established shallow-grave plots at The University of Tennessee Anthropological Research Facility (ARF) that are specific to GPR research. These plots contain donated human cadavers lying in various configurations and depths, surrounded by assorted construction material and backfill debris. We scanned the plots using two GPR technologies: (1) a multi-frequency synthetic-aperture FM-CW radar (200-700 MHz) (GPR-X) developed by the U.S. Department of Energy's (DOE) Special Technologies Laboratory (STL), Bechtel Nevada (Koppenjan et al., 2000), and (2) a commercial pulse radar (SIR-20) manufactured by Geophysical Survey Systems, Inc. (400 and 900 MHz)(GSSI). The sweep-frequency data show the large biological mass decomposing within the torso as encircled ''hot spots.'' The 400-MHz pulse radar exhibit major horizontal reflectors above the body, with shadow reflectors (horizontal multiples) occurring beneath the body at 60 cm depth. The 400-MHz antenna was able to discern the grave walls and folded tarp covering the lower body. Under these moist, clay-rich conditions, the 900-MHz antenna was able to penetrate slightly beyond 30 cm beneath the concrete layer. However, neither system was able to penetrate beyond a one meter depth in the moist, clay-rich soil (fine, mixed, thermic Typic Paleudalf). Example scans from each system are provided, along with a discussion of the survey protocol and general performance.

  20. A point-like source of extreme ultraviolet radiation based on a discharge in a non-uniform gas flow, sustained by powerful gyrotron radiation of terahertz frequency band

    SciTech Connect

    Glyavin, M. Yu.; Golubev, S. V.; Izotov, I. V.; Litvak, A. G.; Luchinin, A. G.; Razin, S. V.; Sidorov, A. V.; Skalyga, V. A.; Vodopyanov, A. V.

    2014-10-27

    The possibility and prospects of extreme ultraviolet (UV) point-like source development are discussed in the present paper. The UV source is based on the discharge sustained by powerful gyrotron radiation of terahertz (THz) frequency band in non-uniform gas flow injected into vacuum volume through a nozzle with diameter less than 1 mm. Recent developments of THz-band gyrotrons with appropriate power level made such discharges possible. First experimental results on a point-like plasma creation by 100 kW radiation of 0.67 THz gyrotron are presented. The possibility of discharge localization within the area less than 1 mm is demonstrated. The discharge emission within the wavelength range from 112 nm to 650 nm was studied. The measured power of light emission in the range of 112–180 nm was measured to be up to 10 kW.

  1. Experimental Procedure for Determination of the Dielectric Properties of Biological Samples in the 2-50 GHz Range

    PubMed Central

    Odelstad, Elias; Raman, Sujith; Rydberg, Anders

    2014-01-01

    The objective of this paper was to test and evaluate an experimental procedure for providing data on the complex permittivity of different cell lines in the 2–50-GHz range at room temperature, for the purpose of future dosimetric studies. The complex permittivity measurements were performed on cells suspended in culture medium using an open-ended coaxial probe. Maxwell’s mixture equation then allows the calculation of the permittivity profiles of the cells from the difference in permittivity between the cell suspensions and pure culture medium. The open-ended coaxial probe turned out to be very sensitive to disturbances affecting the measurements, resulting in poor precision. Permittivity differences were not large in relation to the spread of the measurements and repeated measurements were performed to improve statistics. The 95% confidence intervals were computed for the arithmetic means of the measured permittivity differences in order to test the statistical significance. The results showed that for bone cells at the lowest tested concentration (33 500/ml), there were significance in the real part of the permittivity at frequencies above 30 GHz, and no significance in the imaginary part. For the second lowest concentration (67 000/ml) there was no significance at all. For a medium concentration of bone cells (135 000/ml) there was no significance in the real part, but there was significance in the imaginary part at frequencies below about 25 GHz. The cell suspension with a concentration of 1 350 000/ml had significance in the real part for both high (above 30 GHz) and low (below 15 GHz) frequencies. The imaginary part showed significance for frequencies below 25 GHz. In the case of an osteosarcoma cell line with a concentration of 2 700 000/ml, only the imaginary part showed significance, and only for frequencies below 15 GHz. For muscle cells at a concentration of 743 450/ml, there was only significance in the imaginary part for frequencies below 5 GHz. The experimental data indicated that the complex permittivity of the culture medium may be used for modeling of cell suspensions. PMID:27170886

  2. Study of hydrogen ECR plasma in a simple mirror magnetic trap heated by 75 GHz pulsed gyrotron radiation.

    PubMed

    Skalyga, V A; Izotov, I V; Sidorov, A V; Golubev, S V; Razin, S V

    2017-03-01

    Plasma of electron cyclotron resonance (ECR) discharge sustained by millimeter wave radiation is widely used for production of ion beams of different kind. The main trend in ECR ion sources development nowadays is an increase of frequency and power of microwave heating. The most advanced systems use gyrotrons in 24-60 GHz frequency range. In previous studies at IAP RAS it was demonstrated that ECR source SMIS 37 (Simple Mirror Ion Source) with 37.5 GHz heating operating in quasigasdynamic regime of plasma confinement is able to produce proton and deuteron beams with ion current density about 700 mA/cm(2). As the next step of these investigations plasma properties of the discharge sustained by 75 GHz radiation have been studied. Plasma density and electron temperature were determined using spectroscopic and Langmuir probe techniques. It was demonstrated that plasma density could reach values close to 10(14) cm(-3) and that is of great interest for further development of high current ion sources for various applications.

  3. Magnetron injection gun design for a Q-band 300 kW 30 A gyrotron traveling wave tube

    NASA Astrophysics Data System (ADS)

    Dong, Kun; Luo, Yong; Yan, Ran; Wang, Shafei

    2015-09-01

    This paper is intended to present the optimal design of a triode type magnetron injection gun (MIG) for a 300 kW, 30 A gyrotron traveling wave tube (gyro-TWT), which is operated at Q band fundamental TE01 mode. Based on the analysis of velocity ratio (VR) distribution along the emission strip (ES), a further optimization of cathode geometry on the basis of a preliminary optimized gun is performed, and a new cathode structure is proposed. Compared with initial optimal parameters, the new structure demonstrates a decline of transverse velocity spread (TVS) from 3.66% to 0.57% and longitudinal velocity spread (LVS) from 4.11% to 0.72%, while VR is maintained at 1.05. The achieved overall LVS reaches as low as 3.44% when considering cathode surface roughness and thermal temperature effect. The sensitivity study has been carried out by changing the gun parameters like anode voltage, beam current, and cathode magnetic field to ensure the practical operation stability.

  4. A Stable 0.2-THz Coaxial-Waveguide Gyrotron Traveling-Wave-Tube Amplifier with Distributed Losses

    NASA Astrophysics Data System (ADS)

    Hung, C. L.; Yeh, Y. S.; Chang, T. H.; Fang, R. S.

    2017-01-01

    For high-power operation, a THz gyrotron traveling-wave-tube (gyro-TWT) amplifier must operate in a high-order waveguide mode to enlarge the transverse dimension of an interaction waveguide. However, a gyro-TWT amplifier operating in a high-order waveguide mode is susceptible to spurious oscillations. To improve the device stability, in this study, we investigate the possibility of using a coaxial waveguide with distributed losses as the interaction structure. For the same required attenuation, all threatening oscillating modes can be suppressed using different combinations of losses of inner and outer cylinders. This provides flexibility in designing distributed losses when considering the ohmic loading of the interaction structure. We predict that the 0.2-THz gyro-TWT can stably produce a peak power of 14 kW with an efficiency of 23 %, a 3-dB bandwidth of 3.5 GHz, and a saturated gain of 50 dB for a 20-kV 3-A electron beam with a 5 % velocity spread and 1.0 velocity ratio.

  5. Design and measurement of a TE13 input converter for high order mode gyrotron travelling wave amplifiers

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Liu, Guo; Shu, Guoxiang; Yan, Ran; Wang, Li; Agurgo Balfour, E.; Fu, Hao; Luo, Yong; Wang, Shafei

    2016-03-01

    A technique to launch a circular TE13 mode to interact with the helical electron beam of a gyrotron travelling wave amplifier is proposed and verified by simulation and cold test in this paper. The high order (HOM) TE13 mode is excited by a broadband Y-type power divider with the aid of a cylindrical waveguide system. Using grooves and convex strips loaded at the lateral planes of the output cylindrical waveguide, the electric fields of the potential competing TE32 and TE71 modes are suppressed to allow the transmission of the dominant TE13 mode. The converter performance for different structural dimensions of grooves and convex strips is studied in detail and excellent results have been achieved. Simulation predicts that the average transmission is ˜-1.8 dB with a 3 dB bandwidth of 7.2 GHz (91.5-98.7 GHz) and port reflection is less than -15 dB. The conversion efficiency to the TE32 and TE71 modes are, respectively, under -15 dB and -24 dB in the operating frequency band. Such an HOM converter operating at W-band has been fabricated and cold tested with the radiation boundary. Measurement from the vector network analyzer cold test and microwave simulations show a good reflection performance for the converter.

  6. Study of hydrogen ECR plasma in a simple mirror magnetic trap heated by 75 GHz pulsed gyrotron radiation

    NASA Astrophysics Data System (ADS)

    Skalyga, V. A.; Izotov, I. V.; Sidorov, A. V.; Golubev, S. V.; Razin, S. V.

    2017-03-01

    Plasma of electron cyclotron resonance (ECR) discharge sustained by millimeter wave radiation is widely used for production of ion beams of different kind. The main trend in ECR ion sources development nowadays is an increase of frequency and power of microwave heating. The most advanced systems use gyrotrons in 24-60 GHz frequency range. In previous studies at IAP RAS it was demonstrated that ECR source SMIS 37 (Simple Mirror Ion Source) with 37.5 GHz heating operating in quasigasdynamic regime of plasma confinement is able to produce proton and deuteron beams with ion current density about 700 mA/cm2. As the next step of these investigations plasma properties of the discharge sustained by 75 GHz radiation have been studied. Plasma density and electron temperature were determined using spectroscopic and Langmuir probe techniques. It was demonstrated that plasma density could reach values close to 1014 cm-3 and that is of great interest for further development of high current ion sources for various applications.

  7. High power rf amplifiers for accelerator applications: The large orbit gyrotron and the high current, space charge enhanced relativistic klystron

    SciTech Connect

    Stringfield, R.M.; Fazio, M.V.; Rickel, D.G.; Kwan, T.J.T.; Peratt, A.L.; Kinross-Wright, J.; Van Haaften, F.W.; Hoeberling, R.F.; Faehl, R.; Carlsten, B.; Destler, W.W.; Warner, L.B.

    1990-01-01

    Los Alamos is investigating a number of high power microwave sources for their potential to power advanced accelerators. Included in this investigation are the large orbit gyrotron amplifier and oscillator (LOG) and the relativistic klystron amplifier (RKA). LOG amplifier development is newly underway. Electron beam power levels of 3 GW, 70 ns duration, are planned, with anticipated conversion efficiencies into RF on the order of 20 percent. Ongoing investigations on this device include experimental improvement of the electron beam optics, and computational studies of resonator design and RF extraction. Recent RKA studies have operated at electron beam powers into the device of 1.35 GW in microsecond duration pulses. The device has yielded modulated electron beam power approaching 300 MW using 3--5 kW of RF input drive. RF powers extracted into waveguide have been up to 70 MW, suggesting that more power is available from the device that we have converted to-date in the extractor. We have examined several aspects of operation, including beam bunching phenomena and RF power extraction techniques. In addition, investigations of the amplifier gain as a function of input drive, electron beam parameters and axial magnetic field strength also have been explored. The effect of ions formed during device operation also has been considered.

  8. Comparative analysis of fourth-harmonic multiplying gyrotron traveling-wave amplifiers operating at different frequency multiplications

    NASA Astrophysics Data System (ADS)

    Yeh, Y. S.; Kao, W. J.; Li, L. J.; Guo, Y. W.

    2017-01-01

    The harmonic multiplying operation in a gyrotron traveling-wave amplifier (gyro-TWA) permits magnetic field reduction and frequency multiplication. This study presents a comparative analysis of fourth-harmonic multiplying gyro-TWAs with three schemes of operation. An improved mode-selective circuit using circular waveguides with various radii provides the rejection points within the range of operating frequencies to suppress the competing modes of gyro-TWAs. The simulated results reveal that gyro-TWAs are the most susceptible to the fundamental-harmonic TE11 competing mode, regardless of the operating scheme, and that the mode-selective circuit can provide an attenuation of more than 20 dB to suppress the competing modes. The amplification of the waves in a gyro-TWA depends on the lengths of the sections, and the simulated results show that the gain increases for all schemes, as the length of the lossy section or the length of the copper section increases. All schemes exhibit nearly the same saturated output powers and bandwidths; however, the saturated gain of the scheme at a high frequency multiplication ratio is less than that of the scheme at a low frequency multiplication ratio. Extensive numerical calculations of power and gain scaling are conducted for all schemes.

  9. Design and Implementation of a 200kW, 28GHz gyrotron system for the Compact Toroidal Hybrid Experiment

    NASA Astrophysics Data System (ADS)

    Hartwell, G. J.; Knowlton, S. F.; Ennis, D. A.; Maurer, D. A.; Bigelow, T.

    2016-10-01

    The Compact Toroidal Hybrid (CTH) is an l = 2 , m = 5 torsatron/tokamak hybrid (R0 = 0.75 m, ap 0.2 m, and | B | <= 0.7 T). It can generate its highly configurable confining magnetic fields solely with external coils, but typically operates with up to 80 kA of ohmically-generated plasma current for heating. New studies of edge plasma transport in stellarator geometries will benefit from CTH operating as a pure torsatron with a high temperature edge plasma. Accordingly, a 28 GHz, 200 kW gyrotron operating at 2nd harmonic for ECRH is being installed to supplement the existing 15 kW klystron system operating at the fundamental frequency; the latter will be used to initially generate the plasma. Ray-tracing calculations that guide the selection of launching position, antenna focal length, and beam-steering characteristics of the ECRH have been performed with the TRAVIS code [ 1 ] . The calculated absorption is up to 95.7% for vertically propagating rays, however, the absorption is more sensitive to magnetic field variations than for a side launch where the field gradient is tokamak-like. The design of the waveguide path and components for the top-launch scenario will be presented. This work is supported by U.S. Department of Energy Grant No. DE-FG02-00ER54610.

  10. Ring-Down Spectroscopy for Characterizing a CW Raman Laser

    NASA Technical Reports Server (NTRS)

    Matsko, Andrey; Savchenkov, Anatoliy; Maleki, Lute

    2007-01-01

    .A relatively simple technique for characterizing an all-resonant intracavity continuous-wave (CW) solid-state Raman laser involves the use of ring-down spectroscopy. As used here, characterizing signifies determining such parameters as threshold pump power, Raman gain, conversion efficiency, and quality factors (Q values) of the pump and Stokes cavity modes. Heretofore, in order to characterize resonant-cavity-based Raman lasers, it has usually been necessary to manipulate the frequencies and power levels of pump lasers and, in each case, to take several sets of measurements. In cases involving ultra-high-Q resonators, it also has been desirable to lock pump lasers to resonator modes to ensure the quality of measurement data. Simpler techniques could be useful. In the present ring-down spectroscopic technique, one infers the parameters of interest from the decay of the laser out of its steady state. This technique does not require changing the power or frequency of the pump laser or locking the pump laser to the resonator mode. The technique is based on a theoretical analysis of what happens when the pump laser is abruptly switched off after the Raman generation reaches the steady state. The analysis starts with differential equations for the evolution of the amplitudes of the pump and Stokes electric fields, leading to solutions for the power levels of the pump and Stokes fields as functions of time and of the aforementioned parameters. Among other things, these solutions show how the ring-down time depends, to some extent, on the electromagnetic energy accumulated in the cavity. The solutions are readily converted to relatively simple equations for the parameters as functions of quantities that can be determined from measurements of the time-dependent power levels. For example, the steady-state intracavity conversion efficiency is given by G1/G2 1 and the threshold power is given by Pin(G2/G1)2, where Pin is the steady-state input pump power immediately prior to

  11. LD dual-end-pumped CW Tm:YLF laser

    NASA Astrophysics Data System (ADS)

    Chen, Xin-yu; Zhang, Yu; Yu, Yong-ji; Wang, Chao; Jin, Guang-yong

    2013-09-01

    We report on a LD dual-end-pumped 792nm continuous wave operation Tm:YLF laser. Firstly, the rate equation of LD end-pumped CW operation Tm:YLF laser were established, in which the energy transfer upconversion and without energy transfer upconversion under continuous-wave considerate were considered, as well the pump threshold and the slope efficiency of the laser system were analyzed. Simultaneously, the cavity stability condition and the pattern matching of the plano- concave resonator were analyzed according to ABCD Matrix theory. Comparing respectively the laser threshold and the slope efficiency and optical-optical conversion efficiency under circumstances which the output mirror transmittance of 15% and 23%. In addition, the M2 of the output laser were contrasted and analyzed in adjusting the resonator cavity length by using different radius of curvature of the output mirror in 150mm, 200mm and 300mm all in the above case. As the process of thermal lens focal length changing greater than 90mm, it exhibited that the two fundamental modes in the cavity resonator matched well in numerical simulation when the radius of curvature of the output mirror was 300mm, as well the two fundamental modes matched well when it more than 100mm in a certain pump power. We designed a single LD dual-end-pumped continuous wave operation Tm:YLF laser. Using Tm:YLF (3 at.%) crystal for gain medium, which the size was 3×3×14mm3. In experiments, the Tm:YLF laser crystal keeps 291K and the temperature control method is water cooling. The length of the resonator was 135mm when L shape plano-concave resonator was applied, and the radius of curvature output mirror was 300mm, as well as the temperature of the Tm:YLF laser crystal was 291K. The output laser we observed by this system and the central laser wavelength was 1944nm. The threshold power was 8.11W and the highest output power reaches to 4.01W when the totally input pump power was 17W, and the optical conversion efficiency was 23

  12. Developments in LFM-CW SAR for UAV Operation

    NASA Astrophysics Data System (ADS)

    Stringham, Craig

    Opportunities to use synthetic aperture radar (SAR) in scientific studies and military operations are expanding with the development of small SAR systems that can be operated on small unmanned air vehicles (UAV)s. While the nimble nature of small UAVs make them an attractive platform for many reasons, small UAVs are also more prone to deviate from a linear course due autopilot errors and external forces such as turbulence and wind. Thus, motion compensation and improved processing algorithms are required to properly focus the SAR images. The work of this dissertation overcomes some of the challenges and addresses some of the opportunities of operating SAR on small UAVs. Several contributions to SAR backprojection processing for UAV SARs are developed including: 1. The derivation of a novel SAR backprojection algorithm that accounts for motion during the pulse that is appropriate for narrow or ultra-wide-band SAR. 2. A compensation method for SAR backprojection to enable radiometrically accurate image processing. 3. The design and implementation of a real-time backprojection processor on a commercially available GPU that takes advantage of the GPU texture cache. 4. A new autofocus method that improves the image focus by estimating motion measurement errors in three dimensions, correcting for both amplitude and phase errors caused by inaccurate motion parameters. 5. A generalization of factorized backprojection, which we call the Dually Factorized Backprojection method, that factorizes the correlation integral in both slow-time and fast-time in order to efficiently account for general motion during the transmit of an LFM-CW pulse. Much of this work was conducted in support of the Characterization of Arctic Sea Ice Experiment (CASIE), and the appendices provide substantial contributions for this project as well, including: 1. My work in designing and implementing the digital receiver and controller board for the microASAR which was used for CASIE. 2. A description of

  13. An experimental study on quasi-CW fibre laser drilling of nickel superalloy

    NASA Astrophysics Data System (ADS)

    Marimuthu, S.; Antar, M.; Dunleavey, J.; Chantzis, D.; Darlington, W.; Hayward, P.

    2017-09-01

    Laser drilling of metals and alloys is extensively used in modern manufacturing industries to produce holes of various size and shape. Currently, most laser drilling of aerospace nickel superalloys is performed using Nd:YAG laser. Over the years, many attempts were made to increase the productivity of Nd:YAG lasers drilling process, but with little success. This paper investigates the fundamental aspects of millisecond-pulsed-Quasi-CW-fibre laser drilling of aerospace nickel superalloy. The main investigation concentrates on understanding the Quasi-CW-fibre laser parameters on trepanning laser drilled hole quality and speed. The principal findings are based on controlling the recast layer, oxide layer, hole surface characteristic and fatigue performance of the laser drilled samples. The results showed that the high average power of the quasi-CW-fibre lasers can be effectively used to achieve increased trepanning drilling speed without undermining the drilling quality, which is not feasible with a free-space Nd:YAG laser. Also, low peak power and high frequency (of quasi-CW-fibre laser) can be effectively used to produce better laser drilled holes than the high peak power and low frequency, which is common with the traditional millisecond Nd:YAG drilling processes. Recast layer thickness of around 30 μm can be achieved with a trepanning speed of up to 500 mm/min with single orbit Quasi-CW fibre laser drilling of 0.75 mm hole over 5 mm thick material.

  14. Model for cw laser collisionally induced fluorescence in low-temperature discharges

    PubMed

    Stewart; Smith; Borthwick; Paterson

    2000-08-01

    A perturbed steady-state rate-equation model has been developed for the cw laser collisionally induced fluorescence (LCIF) produced by excitation on one of the 1s-2p noble gas transitions. This work is one part of a wider complementary modeling program which includes cw optogalvanic spectroscopy, optical emission spectroscopy, and optical absorption spectroscopy, with the overall aim of testing all of these models with the same stringently assembled atomic and discharge data set. Our aim here is to demonstrate the principal features of our cw LCIF model by using it to describe our experimental observations produced by pumping transitions originating on the 1s(5) metastable and 1s(4) resonance states of neon atoms in the positive column of a normal glow discharge at 2.0 Torr and a discharge current of 5 mA. The model shows that these cw LCIF spectra are dominated by 1s-2p excitation and electron collisional coupling among the 2p states. We show that the model allows us to quantify explicitly the various individual contributions to each line in the cw LCIF spectra. The theory and analyses presented here apply equally well to other noble gases and we believe can be modified appropriately for trace noble gases in atomic-molecular mixtures.

  15. Single dose toxicity study of IRDye 800CW in Sprague-Dawley rats

    NASA Astrophysics Data System (ADS)

    Marshall, Milton V.; Draney, Daniel; Sevick-Muraca, Eva M.; Olive, D. Michael

    2010-02-01

    Fluorophore-labeled contrast imaging agents are moving toward clinical use as aids in nodal staging and intraoperative resection of tumors. Near-infrared fluorophores with defined toxicity properties will be needed before these agents can be translated to the clinic. The near-infrared dye IRDye 800CW is frequently used in its N-hydroxysuccinamide (NHS) ester form for labeling these agents. Following conjugation or breakdown of a labeled ligand, excess NHS ester is converted to the carboxylate form. We report here the results of a preliminary toxicity study on IRDye 800CW carboxylate in preparation for its use as a labeling moiety for targeted contrast agents. Male and female Sprague Dawley rats were given a single intravenous or intradermal administration of IRDye 800CW carboxylate; indocyanine green was used as a comparative control. Following administration of varying doses of either the dyes or saline, animals were observed for up to fourteen days during which time, hematological, clinical chemistry, enzymological, and histological testing was performed on animal subgroups. Under the conditions tested, a single administration of IRDye 800CW carboxylate intravenously at dose levels of 1, 5 and 20 mg/kg or 20 mg/kg intradermally produced no pathological evidence of toxicity. A dose of 20 mg/kg was identified as the NOAEL (no observed adverse effect level) following IV or ID routes of administration of IRDye 800CW.

  16. Severe neonatal hemolysis due to a maternal antibody to the low-frequency Rh antigen C(w).

    PubMed

    May-Wewers, Julie; Kaiser, Jeffrey R; Moore, Ellen Kay; Blackall, Douglas P

    2006-05-01

    C(w) is a low-frequency antigen in the Rh blood group system with a prevalence of approximately 2% in whites. Although anti-C(w) is not an uncommon antibody in pregnancy (0.1% incidence), clinically significant hemolytic disease of the newborn is highly unusual. We report the case of an infant with severe hyperbilirubinemia and persistent anemia due to a high-titer maternal C(w) antibody. The medical literature relating to maternal C(w) alloimmunization and neonatal outcome is also reviewed. In addition, recommendations are made regarding the management of pregnancies and newborns complicated by antibodies to C(w).

  17. Gated CW-STED microscopy: a versatile tool for biological nanometer scale investigation.

    PubMed

    Vicidomini, Giuseppe; Hernández, Ivan Coto; d'Amora, Marta; Zanacchi, Francesca Cella; Bianchini, Paolo; Diaspro, Alberto

    2014-03-15

    Stimulation emission depletion (STED) microscopy breaks the spatial resolution limit of conventional light microscopy while retaining its major advantages, such as working under physiological conditions. These properties make STED microscopy a perfect tool for investigating dynamic sub-cellular processes in living organisms. However, up to now, the massive dissemination of STED microscopy has been hindered by the complexity and cost of its implementation. Gated CW-STED (gCW-STED) substantially helps solve this problem without sacrificing spatial resolution. Here, we describe a versatile gCW-STED microscope able to speedily image the specimen, at a resolution below 50 nm, with light intensities comparable to the more complicated all-pulsed STED system. We show this ability on calibration samples as well as on biological samples. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Effects of CW interference on the carrier tracking loop of the deep space network

    NASA Technical Reports Server (NTRS)

    Sue, M. K.

    1984-01-01

    A radio-frequency interference (RFI) environment can cause serious problems for communications systems, such as the Deep Space Network (DSN). For this reason, it is necessary to determine first the RFI susceptibility characteristics for DSN receiving systgms. The present investigation is concerned with CW RFI's which are close in frequency to the carrier frequency. The carrier tracking loop is highly sensitive, and this type of RFI will degrade the carrier loop performance before saturation effects become noticeable. The investigation has the objective to develop an analytical model which will make it possible to predict the tracking performance of the Block IV receiver when operated in the presence of a CW RFI in the receiver passband. The Block IV receiver represents one of the DSN receivers. Attention is given to the effects of a CW RFI on a phase-locked loop, the effects of a bandpass limiter, numerical results, experimental verification, and aspects of computer simulation.

  19. Frequency comb generation by CW laser injection into a quantum-dot mode-locked laser.

    PubMed

    Pinkert, T J; Salumbides, E J; Tahvili, M S; Ubachs, W; Bente, E A J M; Eikema, K S E

    2012-09-10

    We report on frequency comb generation at 1.5 μm by injection of a CW laser in a hybridly mode-locked InAs/InP two-section quantum-dot laser (HMLQDL). The generated comb has > 60 modes spaced by ∼ 4.5 GHz and a -20 dBc width of > 100 GHz (23 modes) at > 30 dB signal to background ratio. Comb generation was observed with the CW laser (red) detuned more than 20 nm outside the HMLQDL spectrum, spanning a large part of the gain spectrum of the quantum dot material. It is shown that the generated comb is fully coherent with the injected CW laser and RF frequency used to drive the hybrid mode-locking. This method of comb generation is of interest for the creation of small and robust frequency combs for use in optical frequency metrology, high-frequency (> 100 GHz) RF generation and telecommunication applications.

  20. CW-THz image contrast enhancement using wavelet transform and Retinex

    NASA Astrophysics Data System (ADS)

    Chen, Lin; Zhang, Min; Hu, Qi-fan; Huang, Ying-Xue; Liang, Hua-Wei

    2015-10-01

    To enhance continuous wave terahertz (CW-THz) scanning images contrast and denoising, a method based on wavelet transform and Retinex theory was proposed. In this paper, the factors affecting the quality of CW-THz images were analysed. Second, an approach of combination of the discrete wavelet transform (DWT) and a designed nonlinear function in wavelet domain for the purpose of contrast enhancing was applied. Then, we combine the Retinex algorithm for further contrast enhancement. To evaluate the effectiveness of the proposed method in qualitative and quantitative, it was compared with the adaptive histogram equalization method, the homomorphic filtering method and the SSR(Single-Scale-Retinex) method. Experimental results demonstrated that the presented algorithm can effectively enhance the contrast of CW-THZ image and obtain better visual effect.

  1. The experimental study of a CW 1080 nm multi-point pump fiber laser

    NASA Astrophysics Data System (ADS)

    Zhang, Xuexia; Ge, Tingwu; Ding, Xing; Tan, Qirui; Wang, Zhiyong

    2016-07-01

    In this paper, we report on a CW 1080 nm fiber laser cascaded-pumped by a CW 975 nm diode laser. The fiber used in the experiment has a core diameter of 20 μm (NA  =  0.06), inner clad of 400 μm (NA  =  0.46), and an absorption coefficient of about 1.26 dB m-1 at 975 nm. An output power of 780 W with an optical conversion efficiency of 71% has been achieved at a pump light of 1.1 kW. To the best of our knowledge, this is the first time that a 1080 nm CW fiber laser has used a cascaded-pump coupler.

  2. Design and measurement of a TE{sub 13} input converter for high order mode gyrotron travelling wave amplifiers

    SciTech Connect

    Wang, Yan; Liu, Guo Shu, Guoxiang; Yan, Ran; Wang, Li; Agurgo Balfour, E.; Fu, Hao; Luo, Yong; Wang, Shafei

    2016-03-15

    A technique to launch a circular TE{sub 13} mode to interact with the helical electron beam of a gyrotron travelling wave amplifier is proposed and verified by simulation and cold test in this paper. The high order (HOM) TE{sub 13} mode is excited by a broadband Y-type power divider with the aid of a cylindrical waveguide system. Using grooves and convex strips loaded at the lateral planes of the output cylindrical waveguide, the electric fields of the potential competing TE{sub 32} and TE{sub 71} modes are suppressed to allow the transmission of the dominant TE{sub 13} mode. The converter performance for different structural dimensions of grooves and convex strips is studied in detail and excellent results have been achieved. Simulation predicts that the average transmission is ∼−1.8 dB with a 3 dB bandwidth of 7.2 GHz (91.5–98.7 GHz) and port reflection is less than −15 dB. The conversion efficiency to the TE{sub 32} and TE{sub 71} modes are, respectively, under −15 dB and −24 dB in the operating frequency band. Such an HOM converter operating at W-band has been fabricated and cold tested with the radiation boundary. Measurement from the vector network analyzer cold test and microwave simulations show a good reflection performance for the converter.

  3. Diode pumped CW and passively Q-switched Nd:LGGG laser at 1062 nm

    NASA Astrophysics Data System (ADS)

    Yang, H.; Jia, Z. T.; Zhang, B. T.; He, J. L.; Liu, S. D.; Yang, Y.; Tao, X. T.

    2012-05-01

    We report a Nd:LGGG laser at 1062 nm in the operations of the continuous-wave (CW) and passively Q-switching. The maximum CW output power of 5.62 W was obtained, corresponding to an optical-to-optical conversion efficiency of 49.0% and slope efficiency of 55.9%. By using Cr4+:YAG with initial transmission of 94% as the saturable absorber, for the first time, we got the maximum passively Q-switched output power of 1.21 W, accompanied with a highest pulse repetition rate of 27.1 kHz and a shortest pulse width of 9.1 ns.

  4. Modulated Sine Waves for Differential Absorption Measurements Using a CW Laser System

    NASA Technical Reports Server (NTRS)

    Campbell, Joel F. (Inventor); Lin, Bing (Inventor); Nehrir, Amin R. (Inventor)

    2015-01-01

    A continuous wave Light Detection and Ranging (CW LiDAR) system utilizes two or more laser frequencies and time or range shifted pseudorandom noise (PN) codes to discriminate between the laser frequencies. The performance of these codes can be improved by subtracting out the bias before processing. The CW LiDAR system may be mounted to an artificial satellite orbiting the earth, and the relative strength of the return signal for each frequency can be utilized to determine the concentration of selected gases or other substances in the atmosphere.

  5. The Effects of CW (Chemical Warfare)-Related Chemicals on Social Behavior and Performance

    DTIC Science & Technology

    1985-10-01

    g-o3oi 9\\a AD- The Effects of CW-Related Che~icala onne k So1ial Behavior and Performancec 0) 0o Annual Report Bradford N. Punnell W. Ben Iturrian...11. TITLE (include Security Classification) The Effects of CW-Related Chemicals on Social Behavior and Performance 12. PERSONAL AUTHOR(S) Bradford N...performance that will be sensitive to the effects Ofb/C•4 -related chemicals considered Tor use as l antidotes or prophyractics against-a agents

  6. CW cavity ring-down spectroscopy (CRDS) with a semiconductor optical amplifier as intensity modulator

    NASA Astrophysics Data System (ADS)

    Huang, Haifeng; Lehmann, Kevin K.

    2008-09-01

    We summarized both advantages and disadvantages of different light modulators used in cw-CRDS experiments. For the first time, we introduce the use of a semiconductor optical amplifier (SOA) as light modulator in cw-CRDS. A direct comparison of the sensitivity realized on the same instrument using an SOA as modulator with use of an acousto-optic modulator (AOM) has been made. It is found that the SOA has larger extinction ratio (˜81 dB) than the AOM. For our instrument, with single-shot initial signal-to-noise ratio of 1400:1, these two modulators are found giving equivalent sensitivity.

  7. The relative effects of CW and RP lasers on composites and metals

    NASA Astrophysics Data System (ADS)

    Mueller, George P.

    1995-09-01

    DoD aircraft structural materials include both metals, primarily aluminum, and composites, primarily graphite/epoxy. The effect of lasers on these two materials is considerably different because of the large differences in some of their thermal properties. There are also significant differences depending on whether the laser irradiation is due to a continuous wave (CW) laser or a repetitively pulsed (RP) laser. Using the one-dimensional thermal response code FLIKER the effects of both CW and Rp irradiations on aluminum and graphit/epoxy were modelled. Two classes of effects were examined: the immediate effects during the irradiations and the post irradiation damage effects.

  8. Admittance Test and Conceptual Study of a CW Positron Source for CEBAF

    SciTech Connect

    Golge, Serkan; Hyde, Charles E.; Freyberger, Arne

    2009-09-02

    A conceptual study of a Continuous Wave (CW) positron production is presented in this paper. The Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab (JLAB) operates with a CW electron beam with a well-defined emittance, time structure and energy spread. Positrons created via bremsstrahlung photons in a high-Z target emerge with a large emittance compared to incoming electron beam. An admittance study has been performed at CEBAF to estimate the maximum beam phase space area that can be transported in the LINAC and in the Arcs. A positron source is described utilizing the CEBAF injector electron beam, and directly injecting the positrons into the CEBAF LINAC.

  9. Use of a PCR-based assay for fetal Cw antigen genotyping in a patient with a history of moderately severe hemolytic disease of the newborn due to anti-Cw.

    PubMed

    Reiner, A P; Teramura, G; Aramaki, K M

    1999-01-01

    Anti-Cw is an uncommon cause of clinically significant hemolytic disease of the newborn (HDN). We report an unusually severe case of HDN due to anti-Cw that required phototherapy and exchange transfusion. We also describe a novel PCR-RFLP method for Cw typing of fetal genomic DNA that was used for prenatal diagnosis in a subsequent pregnancy. Following PCR amplification of a 163 bp segment of the RHCE gene containing the nucleotide 122 G to A substitution that corresponds to the Cw allele, Cw types were distinguished by TaqI digestion. PCR-RFLP analysis confirmed that the father and previously affected child were Cw-positive. The fetus was Cw-negative, thus excluding HDN in the current pregnancy and obviating the need for further invasive or noninvasive diagnostic procedures for the remainder of the pregnancy. This case illustrates the utility of PCR-based fetal genotype determination in pregnancies at risk of HDN due to uncommon red cell antibodies such as anti-Cw.

  10. CW and mode-locked operation of Yb(3+)-doped Lu3Al5O12 ceramic laser.

    PubMed

    Nakao, Hiroaki; Shirakawa, Akira; Ueda, Ken-ichi; Yagi, Hideki; Yanagitani, Takagimi

    2012-07-02

    CW laser operation and first mode-locked laser operation of Yb:LuAG ceramic are reported. Efficient CW laser operation was obtained with maximum output power of 2.14 W and a 72% slope efficiency. Femtosecond mode-locked laser operation was achieved with pulse duration of 699 fs and a 200 mW average output power.

  11. 25. C.W. Todd and E.A. Rand, May 1902 'OUTLINE,' SHOWING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. C.W. Todd and E.A. Rand, May 1902 'OUTLINE,' SHOWING END AND SIDE ELEVATIONS OF THE 4,000-VOLT, ATB-TYPE GENERATORS (4 AND 5) - Washington Water Power Company Monroe Street Plant, Units 4 & 5, South Bank Spokane River, below Monroe Street Bridge, Spokane, Spokane County, WA

  12. Study of plasma formation in CW CO2 laser beam-metal surface interaction

    NASA Astrophysics Data System (ADS)

    Azharonok, V. V.; Vasilchenko, Zh V.; Golubev, Vladimir S.; Gresev, A. N.; Zabelin, Alexandre M.; Chubrik, N. I.; Shimanovich, V. D.

    1994-04-01

    An interaction of the cw CO2 laser beam and a moving metal surface has been studied. The pulsed and thermodynamical parameters of the surface plasma were investigated by optical and spectroscopical methods. The subsonic radiation wave propagation in the erosion plasma torch has been studied.

  13. Method for generating high-energy and high repetition rate laser pulses from CW amplifiers

    SciTech Connect

    Zhang, Shukui

    2013-06-18

    A method for obtaining high-energy, high repetition rate laser pulses simultaneously using continuous wave (CW) amplifiers is described. The method provides for generating micro-joule level energy in pico-second laser pulses at Mega-hertz repetition rates.

  14. Characterization of High-power Quasi-cw Laser Diode Arrays

    NASA Technical Reports Server (NTRS)

    Stephen, Mark A.; Vasilyev, Aleksey; Troupaki, Elisavet; Allan, Graham R.; Kashem, Nasir B.

    2005-01-01

    NASA s requirements for high reliability, high performance satellite laser instruments have driven the investigation of many critical components; specifically, 808 nm laser diode array (LDA) pump devices. Performance and comprehensive characterization data of Quasi-CW, High-power, laser diode arrays is presented.

  15. Class-Wide Function-Related Intervention Teams "CW-FIT" Efficacy Trial Outcomes

    ERIC Educational Resources Information Center

    Kamps, Debra; Wills, Howard; Dawson-Bannister, Harriett; Heitzman-Powell, Linda; Kottwitz, Esther; Hansen, Blake; Fleming, Kandace

    2015-01-01

    The purpose of the study was to determine the efficacy of the Class-Wide Function-Related Intervention Teams (CW-FIT) program for improving students' on-task behavior, and increasing teacher recognition of appropriate behavior. The intervention is a group contingency classroom management program consisting of teaching and reinforcing appropriate…

  16. Applications of FM-CW laser radar to antenna contour mapping

    NASA Technical Reports Server (NTRS)

    Slotwinski, A. R.

    1989-01-01

    The FM-CW coherent laser radar concept, based on the FM radar principle which makes use of the coherence and lunability of injection laser diodes, is discussed. Laser radar precision/time tradeoffs, block diagrams, system performance, fiber optic system implantation, and receiver improvements are briefly described.

  17. Implementing Positive Behavior Support in Preschools: An Exploratory Study of CW-FIT Tier 1

    ERIC Educational Resources Information Center

    Jolstead, Krystine A.; Caldarella, Paul; Hansen, Blake; Korth, Byran B.; Williams, Leslie; Kamps, Debra

    2017-01-01

    Challenging behavior in preschool is a serious concern for teachers. Positive behavior interventions and supports (PBIS) have been shown to be effective in reducing such behaviors. Class-Wide Function-Related Intervention Teams (CW-FIT) is a specific multi-tiered intervention for implementing effective classroom management strategies using PBIS…

  18. A comparison between pulsed and CW laser annealing for solar cell applications

    NASA Technical Reports Server (NTRS)

    Jellison, G. E., Jr.; Young, R. T.; Wood, R. F.; Gat, A.

    1980-01-01

    The application of laser processing in solar cell fabrication is considered. Specific emphasis is placed on a process developed for the fabrication of a 16.6% silicon solar cell using pulsed laser processing. Results are presented which compare pulsed laser annealing with CW laser annealing in solar cell fabrication.

  19. Al2O3 half-wave films for long-life CW lasers

    NASA Technical Reports Server (NTRS)

    Ladany, I.; Ettenberg, M.; Lockwood, H. F.; Kressel, H.

    1977-01-01

    Long-term operating-life data are reported for (AlGa)As CW laser diodes. The use of half-wave Al2O3 facet coatings is shown to eliminate facet erosion, allowing stable diode operation at constant current for periods in excess of 10,000 h.

  20. InGaAsP CW Lasers on (110) InP Substrates

    NASA Technical Reports Server (NTRS)

    Hawrylo, F. Z.

    1983-01-01

    Quality InGaAsP/InP CW laser structures grown by conventional liquidphase epitaxy on (110) InP substrates without using special growth procedures. Improved surface quality and grown-layer morphology are attributable to nearlyperfect surface stoichiometry of (110) surface which makes available equal numbers of In and P deposition sites.

  1. Proton beam studies with a 1.25 MeV, cw radio frequency quadrupole linac

    SciTech Connect

    Bolme, G.O.; Hardek, T.W.; Hansborough, L.D.

    1998-12-31

    A high-current, cw linear accelerator has been proposed as a spallation neutron source driver for tritium production. Key features of this accelerator are high current (100 mA), low emittance-growth beam propagation, cw operation, high efficiency, and minimal maintenance downtime. A 268 MHz, cw radio frequency quadrupole (RFQ) LINAC section and klystrode based rf system were obtained from the Chalk River Laboratories and were previously installed at LANL to support systems development and advanced studies in support of cw, proton accelerators. A variation of the Low Energy Demonstration Accelerator (LEDA) proton injector, modified to operate at 50 keV, was mated to the RFQ and was operated to support advance developments for the Accelerator Production of Tritium (APT) program. High current, proton beam studies were completed which focused on the details of injector-RFQ integration, development of beam diagnostics, development of operations procedures, and personnel and equipment safety systems integration. This development led to acceleration of up to 100 mA proton beam.

  2. Multiphoton upconversion process in Tm 3+ doped ZBLAN glass by CW laser irradiation

    NASA Astrophysics Data System (ADS)

    Li, Jianfu; Wang, Xiaoli; Jiang, Zhankui

    2009-11-01

    Blue, even ultraviolet emissions and very strong red emissions have been observed in ZBLAN glass doped with Tm 3+ under 800 nm CW laser excitation. The red emissions were demonstrated to be of sequential two-photon process, while the ultraviolet emissions be of three-photon process, according to the intensity dependence.

  3. Development of a high average power, CW, MM-wave FEL

    SciTech Connect

    Ramian, G.

    1995-12-31

    Important operational attributes of FELs remain to be demonstrated including high average power and single-frequency, extremely narrow-linewidth lasing. An FEL specifically designed to achieve these goals for scientific research applications is currently under construction. Its most salient feature is operation in a continuous-wave (CW) mode with an electrostatically generated, high-current, recirculating, DC electron beam.

  4. Red-light-emitting laser diodes operating CW at room temperature

    NASA Technical Reports Server (NTRS)

    Kressel, H.; Hawrylo, F. Z.

    1976-01-01

    Heterojunction laser diodes of AlGaAs have been prepared with threshold current densities substantially below those previously achieved at room temperature in the 7200-8000-A spectral range. These devices operate continuously with simple oxide-isolated stripe contacts to 7400 A, which extends CW operation into the visible (red) portion of the spectrum.

  5. Class-Wide Function-Related Intervention Teams "CW-FIT" Efficacy Trial Outcomes

    ERIC Educational Resources Information Center

    Kamps, Debra; Wills, Howard; Dawson-Bannister, Harriett; Heitzman-Powell, Linda; Kottwitz, Esther; Hansen, Blake; Fleming, Kandace

    2015-01-01

    The purpose of the study was to determine the efficacy of the Class-Wide Function-Related Intervention Teams (CW-FIT) program for improving students' on-task behavior, and increasing teacher recognition of appropriate behavior. The intervention is a group contingency classroom management program consisting of teaching and reinforcing appropriate…

  6. Implementing Positive Behavior Support in Preschools: An Exploratory Study of CW-FIT Tier 1

    ERIC Educational Resources Information Center

    Jolstead, Krystine A.; Caldarella, Paul; Hansen, Blake; Korth, Byran B.; Williams, Leslie; Kamps, Debra

    2017-01-01

    Challenging behavior in preschool is a serious concern for teachers. Positive behavior interventions and supports (PBIS) have been shown to be effective in reducing such behaviors. Class-Wide Function-Related Intervention Teams (CW-FIT) is a specific multi-tiered intervention for implementing effective classroom management strategies using PBIS…

  7. Heavy metal removal in an UASB-CW system treating municipal wastewater.

    PubMed

    de la Varga, D; Díaz, M A; Ruiz, I; Soto, M

    2013-10-01

    The objective of the present study was to investigate for the first time the long-term removal of heavy metals (HMs) in a combined UASB-CW system treating municipal wastewater. The research was carried out in a field pilot plant constituted for an up-flow anaerobic sludge bed (UASB) digester as a pretreatment, followed by a surface flow constructed wetland (CW) and finally by a subsurface flow CW. While the UASB showed (pseudo) steady state operational conditions and generated a periodical purge of sludge, CWs were characterised by the progressive accumulation and mineralisation of retained solids. This paper analyses the evolution of HM removal from the water stream over time (over a period of 4.7 year of operation) and the accumulation of HMs in UASB sludge and CW sediments at two horizons of 2.7 and 4.0 year of operation. High removal efficiencies were found for some metals in the following order: Sn > Cr > Cu > Pb > Zn > Fe (63-94%). Medium removal efficiencies were registered for Ni (49%), Hg (42%), and Ag (40%), and finally Mn and As showed negative percentage removals. Removal efficiencies of total HMs were higher in UASB and SF units and lower in the last SSF unit. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Use of Self-Management with the CW-FIT Group Contingency Program

    ERIC Educational Resources Information Center

    Kamps, Debra; Conklin, Carl; Wills, Howard

    2015-01-01

    The purpose of the study was to determine the effects of self-management as a tier two enhancement to the group contingency intervention, Class-Wide Function-related Intervention Teams Program (CW-FIT). Two classrooms, first and fourth grade, and two students in each of the classrooms participated in the intervention. The group contingency…

  9. Use of Self-Management with the CW-FIT Group Contingency Program

    ERIC Educational Resources Information Center

    Kamps, Debra; Conklin, Carl; Wills, Howard

    2015-01-01

    The purpose of the study was to determine the effects of self-management as a tier two enhancement to the group contingency intervention, Class-Wide Function-related Intervention Teams Program (CW-FIT). Two classrooms, first and fourth grade, and two students in each of the classrooms participated in the intervention. The group contingency…

  10. Antiviral Potential of a Novel Compound CW-33 against Enterovirus A71 via Inhibition of Viral 2A Protease

    PubMed Central

    Wang, Ching-Ying; Huang, An-Cheng; Hour, Mann-Jen; Huang, Su-Hua; Kung, Szu-Hao; Chen, Chao-Hsien; Chen, I-Chieh; Chang, Yuan-Shiun; Lien, Jin-Cherng; Lin, Cheng-Wen

    2015-01-01

    Enterovirus A71 (EV-A71) in the Picornaviridae family causes hand-foot-and-mouth disease, aseptic meningitis, severe central nervous system disease, even death. EV-A71 2A protease cleaves Type I interferon (IFN)-α/β receptor 1 (IFNAR1) to block IFN-induced Jak/STAT signaling. This study investigated anti-EV-A7l activity and synergistic mechanism(s) of a novel furoquinoline alkaloid compound CW-33 alone and in combination with IFN-β. Anti-EV-A71 activities of CW-33 alone and in combination with IFN-β were evaluated by inhibitory assays of virus-induced apoptosis, plaque formation, and virus yield. CW-33 showed antiviral activities with an IC50 of near 200 μM in EV-A71 plaque reduction and virus yield inhibition assays. While, anti-EV-A71 activities of CW-33 combined with 100 U/mL IFN-β exhibited a synergistic potency with an IC50 of approximate 1 μM in plaque reduction and virus yield inhibition assays. Molecular docking revealed CW-33 binding to EV-A71 2A protease active sites, correlating with an inhibitory effect of CW33 on in vitro enzymatic activity of recombinant 2A protease (IC50 = 53.1 μM). Western blotting demonstrated CW-33 specifically inhibiting 2A protease-mediated cleavage of IFNAR1. CW-33 also recovered Type I IFN-induced Tyk2 and STAT1 phosphorylation as well as 2′,5′-OAS upregulation in EV-A71 infected cells. The results demonstrated CW-33 inhibiting viral 2A protease activity to reduce Type I IFN antagonism of EV-A71. Therefore, CW-33 combined with a low-dose of Type I IFN could be applied in developing alternative approaches to treat EV-A71 infection. PMID:26090728

  11. Anti-fibrotic effects of a methylenedioxybenzene compound, CW209292 on dimethylnitrosamine-induced hepatic fibrosis in rats.

    PubMed

    Oh, Se-Woong; Kim, Dae-Hoon; Ha, Jong-Ryul; Kim, Dae-Yong

    2009-08-01

    A series of methylenedioxybenzene compounds were synthesized and found to have hepatoprotective effects in chemical-induced hepatotoxicity models. The purpose of the present study was to investigate the anti-fibrotic effects of a synthetic methylenedioxybenzene compound, CW209292, using the dimethylnitrosamine (DMN)-induced chronic liver injury model in rats. Liver injuries were induced in Sprague Dawley rats by injection of DMN (intraperitoneally, 10 microl/kg) 3 times per week for 4 weeks. The rats were treated with CW209292 (per os, 25 or 75 mg/kg/d) for 4 weeks. Treatment of rats with DMN for 4 weeks resulted in significant decreases in serum albumin levels, whereas concomitant treatment with CW209292 prevented these decreases. CW209292 treatment also shortened prothrombin time prolonged by DMN, providing evidence that the agent was active in preserving liver function against DMN insult. DMN treatment caused marked increases in plasma bilirubin, aspartate aminotransferase (AST), alanine transaminase (ALT), and hyaluronic acid levels; CW209292 treatment reversed these increases. CW209292 also significantly reduced hepatic hydroxyproline content as well as hepatic fibrosis and inflammation in histological examination. Additionally, immunochemically detectable hepatic collagen type IV and alpha-smooth muscle actin levels were decreased by CW209292 treatment. Proliferation of hepatic stellate cells isolated from DMN-treated rats was inhibited by CW209292. Furthermore, tumor growth factor (TGF)-beta1 mRNA expression was increased in DMN-treated rats, whereas CW209292 treatment prevented these increases. These results suggest that CW209292 exhibits anti-fibrotic effects in Sprague Dawley rats with DMN-induced hepatic fibrosis by blocking the mRNA expression of TGF-beta1 and subsequent inhibition of the proliferation of hepatic stellate cells.

  12. CW mode locked Nd:YVO4 laser pumped by 20-W laser diode bar

    NASA Astrophysics Data System (ADS)

    Jabczyński, J. K.; Żendzian, W.; Kwiatkowski, J.

    2006-06-01

    The efficient cw mode locking (cw-ML) regime was demonstrated in Nd:YVO4 laser by means of saturable absorber mirror (SAM). The 0.3-at.% Nd3+ doped 10-mm-long YVO4 crystal end pumped by 20-W diode module with a beam shaper was applied as a gain medium located in the close vicinity to the rear flat mirror of the first arm of Z-type resonator of 316 cm total length with two curved mirrors of 100-cm curvature radii. The SAM of 2%-saturable absorptance and saturation fluence of 50 μJ/cm2 was mounted at the opposite end of a resonator. The developed "dynamically stable" cavity design mitigates detrimental role of thermal aberration in gain medium, enforcing clean perfect mode locking even for the highest pump densities. The cw-ML pulses with 47.5 MHz repetition rate and pulse durations in the range of 15-20 ps were observed for a wide range of pump powers and output coupler losses. In the best case, for 32% of output coupler transmission, up to 6.2 W of average power with near 35% slope efficiency was achieved. The thresholds for Q-switched ML, cw-ML regimes were 2.67 W and 6.13 W of pump power, respectively. For the maximum pump power of 20 W we obtained 133 nJ of pulse energy with 16-ps pulse duration, resulting in a peak power higher than 8 kW. The threshold energy density at SAM giving the QML regime was estimated to be about 30 μJ/cm2, threshold of cw-ML regime was 220 μJ/cm2.

  13. Sequence and Structural Characterization of Great Salt Lake Bacteriophage CW02, a Member of the T7-Like Supergroup

    PubMed Central

    Shen, Peter S.; Sanz-García, Eduardo; Makaju, Aman; Taylor, Ryan M.; Hoggan, Ryan; Culumber, Michele D.; Oberg, Craig J.; Breakwell, Donald P.; Prince, John T.

    2012-01-01

    Halophage CW02 infects a Salinivibrio costicola-like bacterium, SA50, isolated from the Great Salt Lake. Following isolation, cultivation, and purification, CW02 was characterized by DNA sequencing, mass spectrometry, and electron microscopy. A conserved module of structural genes places CW02 in the T7 supergroup, members of which are found in diverse aquatic environments, including marine and freshwater ecosystems. CW02 has morphological similarities to viruses of the Podoviridae family. The structure of CW02, solved by cryogenic electron microscopy and three-dimensional reconstruction, enabled the fitting of a portion of the bacteriophage HK97 capsid protein into CW02 capsid density, thereby providing additional evidence that capsid proteins of tailed double-stranded DNA phages have a conserved fold. The CW02 capsid consists of bacteriophage lambda gpD-like densities that likely contribute to particle stability. Turret-like densities were found on icosahedral vertices and may represent a unique adaptation similar to what has been seen in other extremophilic viruses that infect archaea, such as Sulfolobus turreted icosahedral virus and halophage SH1. PMID:22593163

  14. Automated Microwave Complex on the Basis of a Continuous-Wave Gyrotron with an Operating Frequency of 263 GHz and an Output Power of 1 kW

    NASA Astrophysics Data System (ADS)

    Glyavin, M. Yu.; Morozkin, M. V.; Tsvetkov, A. I.; Lubyako, L. V.; Golubiatnikov, G. Yu.; Kuftin, A. N.; Zapevalov, V. E.; V. Kholoptsev, V.; Eremeev, A. G.; Sedov, A. S.; Malygin, V. I.; Chirkov, A. V.; Fokin, A. P.; Sokolov, E. V.; Denisov, G. G.

    2016-02-01

    We study experimentally the automated microwave complex for microwave spectroscopy and diagnostics of various media, which was developed at the Institute of Applied Physics of the Russian Academy of Sciences in cooperation with GYCOM Ltd. on the basis of a gyrotron with a frequency of 263 GHz and operated at the first gyrofrequency harmonic. In the process of the experiments, a controllable output power of 0 .1 -1 kW was achieved with an efficiency of up to 17 % in the continuous-wave generation regime. The measured radiation spectrum with a relative width of about 10 -6 and the frequency values measured at various parameters of the device are presented. The results of measuring the parameters of the wave beam, which was formed by a built-in quasioptical converter, as well as the data obtained by measuring the heat loss in the cavity and the vacuum output window are analyzed.

  15. 11-GHz waveguide Nd:YAG laser CW mode-locked with single-layer graphene

    PubMed Central

    Okhrimchuk, Andrey G.; Obraztsov, Petr A.

    2015-01-01

    We report stable, passive, continuous-wave (CW) mode-locking of a compact diode-pumped waveguide Nd:YAG laser with a single-layer graphene saturable absorber. The depressed cladding waveguide in the Nd:YAG crystal is fabricated with an ultrafast laser inscription method. The saturable absorber is formed by direct deposition of CVD single-layer graphene on the output coupler. The few millimeter-long cavity provides generation of 16-ps pulses with repetition rates in the GHz range (up to 11.3 GHz) and 12 mW average power. Stable CW mode-locking operation is achieved by controlling the group delay dispersion in the laser cavity with a Gires–Tournois interferometer. PMID:26052678

  16. Development of a 9.3 micrometer CW LIDAR for the study of atmospheric aerosol

    NASA Technical Reports Server (NTRS)

    Whiteside, B. N.; Schotland, R. M.

    1993-01-01

    This report provides a brief summary of the basic requirements to obtain coherent or heterodyne mixing of the optical radiation backscattered by atmospheric aerosols with that from a fixed frequency source. The continuous wave (CW) mode of operation for a coherent lidar is reviewed along with the associated lidar transfer equation. A complete optical design of the three major subsystems of a CW, coherent lidar is given. Lens design software is implemented to model and optimize receiver performance. Techniques for the opto-mechanical assembly and some of the critical tolerances of the coherent lidar are provided along with preliminary tests of the subsystems. Included in these tests is a comparison of the experimental and the theoretical average power signal-to-noise ratio. The analog to digital software used to evaluate the power spectrum of the backscattered signal is presented in the Appendix of this report.

  17. Upgrade and validation on plasma of the Tore Supra CW LHCD generator

    SciTech Connect

    Delpech, L.; Achard, J.; Armitano, A.; Berger-By, G.; Bertrand, E.; Bouquey, F.; Chaix, J. P.; Corbel, E.; Crest, I.; Ekedahl, A.; Faisse, F.; Fejoz, P.; Garibaldi, P.; Goletto, C.; Lebourg, P.; Leroux, F.; Lombard, G.; Magne, R.; Martinez, A.; Moreau, M.

    2011-12-23

    A one year-long major upgrade of the 3.7 GHz Lower Hybrid Current Drive (LHCD) generator for the Tore Supra (TS) tokamak has been performed. It consisted in installing a first series of eight Thales Electron Devices (TED) 700 kW CW klystrons, new CW components and auxiliaries, and in modifying the transmitter control and protection software. Modifications and calibration of the sensors and the RF subsystems were completed as well. Finally, the RF power available in the generator has been increased by 35% and the pulse duration could reach 1000 s. A complete validation and optimization of the klystrons have been performed in 2010 on matched load before the generator could enter into operation. The eight klystrons connected with the Full Active Multijunction (FAM) antenna delivered 3.5 MW/50s in December 2010. The upgrade of the generator and the steps to validate the modifications are described.

  18. CW Interference Effects on High Data Rate Transmission Through the ACTS Wideband Channel

    NASA Technical Reports Server (NTRS)

    Kerczewski, Robert J.; Ngo, Duc H.; Tran, Quang K.; Tran, Diepchi T.; Yu, John; Kachmar, Brian A.; Svoboda, James S.

    1996-01-01

    Satellite communications channels are susceptible to various sources of interference. Wideband channels have a proportionally greater probability of receiving interference than narrowband channels. NASA's Advanced Communications Technology Satellite (ACTS) includes a 900 MHz bandwidth hardlimiting transponder which has provided an opportunity for the study of interference effects of wideband channels. A series of interference tests using two independent ACTS ground terminals measured the effects of continuous-wave (CW) uplink interference on the bit-error rate of a 220 Mbps digitally modulated carrier. These results indicate the susceptibility of high data rate transmissions to CW interference and are compared to results obtained with a laboratory hardware-based system simulation and a computer simulation.

  19. Differential high-resolution stimulated CW Raman spectroscopy of hydrogen in a hollow-core fiber.

    PubMed

    Westergaard, Philip G; Lassen, Mikael; Petersen, Jan C

    2015-06-15

    We demonstrate sensitive high-resolution stimulated Raman measurements of hydrogen using a hollow-core photonic crystal fiber (HC-PCF). The Raman transition is pumped by a narrow linewidth (< 50 kHz) 1064 nm continuous-wave (CW) fiber laser. The probe light is produced by a homebuilt CW optical parametric oscillator (OPO), tunable from around 800 nm to 1300 nm (linewidth ∼ 5 MHz). These narrow linewidth lasers allow for an excellent spectral resolution of approximately 10(-4) cm(-1). The setup employs a differential measurement technique for noise rejection in the probe beam, which also eliminates background signals from the fiber. With the high sensitivity obtained, Raman signals were observed with only a few mW of optical power in both the pump and probe beams. This demonstration allows for high resolution Raman identification of molecules and quantification of Raman signal strengths.

  20. Tunable CW all-fiber optical parametric oscillator operating below 1 μm.

    PubMed

    Zlobina, Ekaterina A; Kablukov, Sergey I; Babin, Sergey A

    2013-03-25

    CW all-fiber optical parametric oscillator (FOPO) with tuning range from 950 to 1010 nm is demonstrated using birefringent photonic crystal fiber pumped by an Ytterbium-doped fiber laser (YDFL) near 1 μm. CW parametric generation with spectral linewidth of 3.7 nm at 972 nm has been obtained with slope efficiency as high as 9.4% and output power of up to 460 mW. It is also shown that the FOPO slope efficiency reaches 25% after narrowing of the pump spectrum down to 40 pm. At that the generated power exceeds 1 W, but in this case the generated radiation is modulated with 48 ns period and 50% duty factor due to pump laser power modulation which is probably caused by stimulated Brillouin back scattering.