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Sample records for high power gyrotrons

  1. 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.

  2. Progress of high power 170 GHz gyrotron in JAEA

    NASA Astrophysics Data System (ADS)

    Sakamoto, Keishi; Kasugai, Atsushi; Kajiwara, Ken; Takahashi, Koji; Oda, Yasuhisa; Hayashi, Kazuo; Kobayashi, Noriyuki

    2009-09-01

    Recent progress on the high power gyrotron development in JAEA is presented. The gyrotron is featured to have a triode-type magnetron injection gun, a cylindrical resonator working at 170 GHz with TE31,8 mode, a water-cooled diamond window and a depressed collector. After the demonstration of the ITER basic performance, the gyrotron has been operated for 3 years, and recorded ~200 GJ of total output energy. Next, a gyrotron which oscillates in higher order resonator mode, TE31,12, is designed and fabricated to study the long pulse oscillation at greater than 1 MW. In parallel, feasibility studies of a CW-power modulation for neoclassical tearing mode stabilization, a dual frequency gyrotron and a rapid frequency control are carried out. It is shown that these gyrotrons will be available with current technology.

  3. 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.

  4. 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.

  5. 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.

  6. Liquid state DNP using a 260 GHz high power gyrotron.

    PubMed

    Denysenkov, Vasyl; Prandolini, Mark J; Gafurov, Marat; Sezer, Deniz; Endeward, Burkhard; Prisner, Thomas F

    2010-06-14

    Dynamic nuclear polarization (DNP) at high magnetic fields (9.2 T, 400 MHz (1)H NMR frequency) requires high microwave power sources to achieve saturation of the EPR transitions. Here we describe the first high-field liquid-state DNP results using a high-power gyrotron microwave source (20 W at 260 GHz). A DNP enhancement of -29 on water protons was obtained for an aqueous solution of Fremy's Salt; in comparison the previous highest value was -10 using a solid-state microwave power source (maximum power 45 mW). The increased enhancements are partly due to larger microwave saturation and elevated sample temperature. These experimentally observed DNP enhancements, which by far exceed the predicted values extrapolated from low-field DNP experiments, demonstrate experimentally that DNP is possible in the liquid state also at high magnetic fields. PMID:20461255

  7. Low-Q cavities for high-power gyrotrons

    SciTech Connect

    Zapevalov, V.E.; Kalynov, Y.K.; Kuftin, A.N.

    1994-09-01

    The parameters of free oscillations in gyrotoron resonators with a lowered reflection from the diffractive energy output for the purpose of reducing ohmic heating by rf power loss have been calculated. A gyrotron with such a cavity has been studied experimentally. The gyrotron had an efficiency of more than 45% with an output of 350 to 700 kW when operating in the 3.6-mm H{sub 11,3} mode.

  8. Generation of high power sub-terahertz radiation from a gyrotron with second harmonic oscillation

    SciTech Connect

    Saito, Teruo; Yamada, Naoki; Ikeuti, Shinji; Tatematsu, Yoshinori; Ikeda, Ryosuke; Ogawa, Isamu; Idehara, Toshitaka; Ogasawara, Shinya; Manuilov, Vladimir N.; Shimozuma, Takashi; Kubo, Shin; Nishiura, Masaki; Tanaka, Kenji; Kawahata, Kazuo

    2012-06-15

    New power records of second harmonic gyrotron oscillation have been demonstrated in the sub-THz band. The first step gyrotron of demountable type had succeeded in oscillation with power more than 50 kW at 350 GHz and nearly 40 kW at 390 GHz [T. Notake et al., Phys. Rev. Lett. 103, 225002 (2009)]. Then, the second step gyrotron of sealed-off type was manufactured. A cavity mode was carefully selected to avoid mode competition with a neighboring fundamental harmonic mode. Matching of the selected mode with the electron gun was also circumspectly considered. The second step gyrotron has attained higher power radiation than the first gyrotron. The maximum single mode power was 62 kW at 388 GHz. Then, the electron gun was modified for use of a different cavity mode with a higher coupling coefficient than that for the 62 kW mode. The new mode proved single mode oscillation power of 83 kW at about 389 GHz. These results are new second-harmonic-oscillation power records for sub-THz gyrotrons. The present study constitutes foundations of development of high power second harmonic sub-THz gyrotron for application to collective Thomson scattering measurement on fusion plasmas, especially on high-density plasmas such as those produced in LHD [N. Ohyabu et al., Phys. Rev. Lett. 97, 055002 (2006)]. This paper reports the design consideration to realize high power single mode gyrotron oscillation at second harmonic and the examination of oscillation characteristics of the gyrotron.

  9. 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.

  10. High-power operation of a 170 GHz megawatt gyrotron

    SciTech Connect

    Kreischer, K.E.; Kimura, T.; Danly, B.G.; Temkin, R.J.

    1997-05-01

    Recent gyrotron oscillator experiments have achieved record powers at 170 GHz. Single mode emission with a peak output power of 1.5 MW and an efficiency of 35{percent} has been measured. The experiment is based on a resonant TE{sub 28,8,1} cylindrical cavity situated in a 6.7 T magnetic field. 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{percent}{endash}36{percent} have been measured over a wide range of operating parameters for the TE{sub 28,8,1} mode. Similar results were also achieved in the neighboring TE{sub 27,8,1} mode at 166.6 GHz, and the TE{sub 29,8,1} mode at 173.5 GHz. The high output power is the result of a carefully designed electron gun with low perpendicular velocity spread (6{percent}{endash}10{percent}) and a novel cavity with an output iris that is less prone to mode competition. These results are in good agreement with nonlinear multimode simulations. {copyright} {ital 1997 American Institute of Physics.}

  11. 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.

  12. Effect of velocity spread on operation of high power gyrotrons

    SciTech Connect

    Levush, B.; Cai, S.Y.; Antonsen, T.M. Jr.; Guss, W.C.; Basten, M.A.; Kreischer, K.E.; Temkin, R.

    1995-12-31

    The effect of velocity spread on the operation of 140 GHz gyrotrons has been studied. The performance of two cavities, with low and high Q, has been examined experimentally and theoretically. The simulation code MAGY was modified to include the measured velocity distribution function and the measured pitch angle in order to compare the measured efficiencies with the predicted efficiencies. Based on measurements, the inferred velocity spread at a beam current of 40 A is given by {l_angle}{delta}{upsilon}{sub {perpendicular}}/{upsilon}{sub {perpendicular}}{r_angle}{sub RMS} = 15%. Simulations with this spread produced efficiencies lower than those measured. However, it was found that assuming {l_angle}{delta}{upsilon}{sub {perpendicular}}/{upsilon}{sub {perpendicular}}{r_angle}{sub RMS} = 10% for 40 A current and using the experimentally determined dependence of the spread on the current the calculated efficiencies agree well with the measured efficiencies for the low Q cavity. The efficiency of the low Q gyrotron at 40 A beam current is only 27%. For the same beam current and velocity spread the efficiency of the high Q gyrotron was predicted to be 40% which agrees well with the measured efficiency of 39%.

  13. 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.

  14. Design of Cathode Heater Assembly for High Power Gyrotron

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Ranajoy; Khatun, Hasina; Singh, Narendra Kr.; Singh, Udaybir; Sinha, A. K.

    2013-04-01

    A 3D model of dispenser cathode with toroid shape heater assembly is simulated using simulation software, ANSYS Multi-physics. The reported design study of cathode heater assembly of 1 MW 120 GHz gyrotron helps to optimize the input heater power with respect to cathode surface temperature. The simulation study shows that the input power depends strongly on the heater dimension as well as material properties including the potting material. The optimum input power helps to achieve desired current density (10 A/cm2) and cathode surface temperature (1000 °C). Further, the thermal and structural analyses are carried out to study the temperature distribution on the cathode assembly due to the heat dissipation and mechanical strength of the assembly.

  15. 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.

  16. 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.

  17. State-of-the-art and recent developments of high-power gyrotron oscillators

    NASA Astrophysics Data System (ADS)

    Thumm, Manfred

    1999-05-01

    Gyrotron oscillators (gyromonotrons) are mainly used as high-power millimeter wave sources for electron cyclotron resonance heating (ECRH) and diagnostics of magnetically confined plasmas for generation of energy by controlled thermonuclear fusion. High unit power and high efficiency single-mode CW gyrotrons with conventional cylindrical (1 MW) and advanced coaxial (2 MW) cavities are worldwide under development. 118 GHz, 140 GHz and 170 GHz conventional cavity gyrotrons with output power Pout≈0.5 MW, pulse length τ≈5.0 s and efficiency η≈35% are commercially available. Advanced internal quasi-optical mode converters generate linearly polarized output wave beams from the high-order cavity modes (e.g., TE22,6) with efficiencies of 90-95% and separate the millimeter-wave beam from the electron beam, thus allowing the use of large CW-relevant depressed collectors for energy recovery. Overall efficiencies between 50 and 60% have been already achieved at JAERI, FZK, and GYCOM employing single-stage depressed collectors (SDC). First successful experiments at FZK employing a broadband Brewster window gave up to 1.5 MW output power at around 50% efficiency (SDC) for all operating mode series in the frequency range from 114 to 166 GHz (frequency tuning in 3.7 GHz steps by variation of the magnetic field strength in the cavity). Gyrotrons with advanced coaxial cavities designed for operation in the TE28,16 and TE31,17 modes at 140 and 165 GHz, respectively, are under development and test at IAP Nizhny Novgorod and FZK Karlsruhe. A maximum output power of 1.7 MW has been measured at 165 GHz with an efficiency of 35.2% (SDC, FZK). Cryogenically edge-cooled single-disk sapphire (T=77 K) and Au-doped silicon (T=230 K) windows as well as CVD-diamond windows with water edge-cooling at room temperature are under investigation in order to solve the window problem. Commercial CVD-diamond disks will easily allow the transmission of 2 MW power level at 170 GHz, CW. Bonding and

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

    NASA Astrophysics Data System (ADS)

    Dumbrajs, O.; Nusinovich, G. S.

    2010-05-01

    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.

  19. 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.

  20. 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. PMID:18315170

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

    SciTech Connect

    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.

    2008-02-15

    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 {mu}s, 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.

  2. Formation of a laminar electron flow for 300 GHz high-power pulsed gyrotron

    SciTech Connect

    Yamaguchi, Yuusuke; Tatematsu, Yoshinori; Saito, Teruo; Ikeda, Ryosuke; Mudiganti, Jagadish C.; Ogawa, Isamu; Idehara, Toshitaka

    2012-11-15

    This paper describes the design of a triode magnetron injection gun for use in a 200 kW, 300 GHz gyrotron. As power and frequency increase, the performance of the gyrotron becomes quite sensitive to the quality of the electron beam. Formation of a laminar electron flow is essential for the realization of a high quality beam with a small velocity spread. In this study, a new method is developed for a quantitative evaluation of the laminarity and is applied to optimize the electrode design. The laminarity depends not only on conventional design parameters such as the cathode slant angle but also on the spatial distribution of the electric field along the beam trajectory. In the optimized design, the velocity pitch factors, {alpha}, larger than 1.2 are obtained at 65 kV, 10 A with spreads, {Delta}{alpha}, less than 5%.

  3. Formation of a laminar electron flow for 300 GHz high-power pulsed gyrotron

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Yuusuke; Tatematsu, Yoshinori; Saito, Teruo; Ikeda, Ryosuke; Mudiganti, Jagadish C.; Ogawa, Isamu; Idehara, Toshitaka

    2012-11-01

    This paper describes the design of a triode magnetron injection gun for use in a 200 kW, 300 GHz gyrotron. As power and frequency increase, the performance of the gyrotron becomes quite sensitive to the quality of the electron beam. Formation of a laminar electron flow is essential for the realization of a high quality beam with a small velocity spread. In this study, a new method is developed for a quantitative evaluation of the laminarity and is applied to optimize the electrode design. The laminarity depends not only on conventional design parameters such as the cathode slant angle but also on the spatial distribution of the electric field along the beam trajectory. In the optimized design, the velocity pitch factors, α, larger than 1.2 are obtained at 65 kV, 10 A with spreads, Δα, less than 5%.

  4. Formation of Laminar Electron Flow for a High-Power Sub-THz Gyrotron

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Yuusuke; Tatematsu, Yoshinori; Saito, Teruo; Ikeda, Ryosuke; Mudiganti, Jagadish C.; Ogawa, Isamu; Idehara, Toshitaka

    This paper describes the design of a magnetron-injection gun for a 100 kW, 300 GHz gyrotron. With an increase in power and frequency, performance of the gyrotron becomes quite sensitive to the quality of the electron beam. Formation of a laminar electron flow is essential for the realization of a high quality beam with small velocity spread. In this study, a new method is proposed for the evaluation of the laminarity, and applied to the design optimization of the electrodes. It is found that the laminarity depends not only on the conventional design parameter of the cathode slant angle, but also on the spatial distribution of the electric field inside the beam.

  5. 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.

  6. Silicon as an advanced window material for high power gyrotrons

    SciTech Connect

    Parshin, V.V.; Andreev, B.A.; Gusev, A.V.

    1995-05-01

    The absorptivity of high-purity grades of silicon (Si) and its reduction by subsequent doping procedures are investigated. The dielectric data are given for the wide range of frequencies (30 -330 GHz) and temperatures (30 -330 K) in comparison with the data set for sapphire. The advanced material performance in high power window applications is discussed taking into account both dielectric properties of the optimized silicon grades and thermal conductivity.

  7. 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.

  8. Using High-Power Gyrotrons in the T-10 Tokamak

    NASA Astrophysics Data System (ADS)

    Kislov, A. Ya.; Lysenko, S. E.; Notkin, G. E.

    2016-02-01

    In this work, we briefly review the T-10 tokamak experiments on the interaction of microwaves with the plasma in the electron-cyclotron resonance frequency range. The basic results on the electron-cyclotron heating and the noninductive current generation in the plasma at both the first and second cyclotron harmonics are presented along with the typical values of the heating and current-generation efficiencies. The possibility of using the local contribution of the high-frequency power to control the sawtooth-oscillation instability and the amplitudes of the neoclassical tearing modes is demonstrated. Using the injection of the high-frequency waves for the working-gas preionization, allows one to optimize both the breakdown phase in the absence of a rotational electric field and the discharge-current increase stage.

  9. 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.

  10. High-power 140-GHz quasioptical gyrotron traveling-wave amplifier.

    PubMed

    Sirigiri, J R; Shapiro, M A; Temkin, R J

    2003-06-27

    We present the design and experimental results of a novel quasioptical gyrotron traveling-wave tube (gyro-TWT) amplifier at 140 GHz. The gyro-TWT produced up to 30 kW of peak power in 2 micros pulsed operation at 6 Hz achieving a peak gain of 29 dB, a peak efficiency of 12%, and a bandwidth of 2.3 GHz. The device was operated in a very higher-order mode of an open quasioptical interaction structure, namely, a confocal waveguide. The diffraction loss from the open sidewalls of the confocal waveguide was used to suppress mode competition in this highly overmoded circuit resulting in a stable single-mode operation. The experiment achieved record high power levels at 140 GHz for a gyro-TWT. These experiments demonstrate the effectiveness of using overmoded quasioptical waveguide interaction structures for generating high power in the millimeter and submillimeter wave bands with a gyro-TWT. PMID:12857176

  11. Development of a novel high power sub-THz second harmonic gyrotron.

    PubMed

    Notake, T; Saito, T; Tatematsu, Y; Fujii, A; Ogasawara, S; Agusu, La; Ogawa, I; Idehara, T; Manuilov, V N

    2009-11-27

    Record-breaking high power coherent radiation at a subterahertz frequency region from a gyrotron utilizing second harmonic resonance modes was attained with a simple cavity. In order to aim at high power and high frequency simultaneously, the oscillation mode was selected carefully enough to realize stable radiation free from mode competition. The cavity radius was determined from the viewpoints of the oscillation frequency, the coupling coefficient between the electron beam, and the rf-electric field. The cavity length was also optimized for the highest perpendicular efficiency. In addition, a new electron gun which is capable of generating a thin laminar beam for a large current was introduced. Consequently, single mode second harmonic radiation with powers of 52 and 37 kW at frequencies of about 349 and 390 GHz, respectively, was achieved. PMID:20366101

  12. Development of a Novel High Power Sub-THz Second Harmonic Gyrotron

    SciTech Connect

    Notake, T.; Saito, T.; Tatematsu, Y.; Fujii, A.; Ogasawara, S.; Agusu, La; Ogawa, I.; Idehara, T.; Manuilov, V. N.

    2009-11-27

    Record-breaking high power coherent radiation at a subterahertz frequency region from a gyrotron utilizing second harmonic resonance modes was attained with a simple cavity. In order to aim at high power and high frequency simultaneously, the oscillation mode was selected carefully enough to realize stable radiation free from mode competition. The cavity radius was determined from the viewpoints of the oscillation frequency, the coupling coefficient between the electron beam, and the rf-electric field. The cavity length was also optimized for the highest perpendicular efficiency. In addition, a new electron gun which is capable of generating a thin laminar beam for a large current was introduced. Consequently, single mode second harmonic radiation with powers of 52 and 37 kW at frequencies of about 349 and 390 GHz, respectively, was achieved.

  13. High-power gyrotron traveling-wave amplifier with distributed wall losses and attenuating severs

    SciTech Connect

    Yeh, Y.S.; Shin, Y.Y.; You, Y.C.; Chen, L.K.

    2005-04-15

    Distributed-loss gyrotron traveling-wave amplifiers (gyro-TWTs) with high-gain, broadband, and millimeter-wave capabilities have been demonstrated. Most structures with distributed wall losses 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. Simulation results show that gyrotron backward-wave oscillations (gyro-BWOs) are not effectively suppressed by the lossy section; in contrast, the severed sections can effectively enhance the start-oscillation threshold of gyro-BWOs in the proposed gyro-TWT. Meanwhile, localized reflective oscillations seem not to occur in the gyro-TWT unless it operates at a high magnetic field or with a high interaction length. The stable gyro-TWT, operating in the low-loss TE{sub 01} mode, is predicted to yield a peak output power of 405 kW at 33 GHz with an efficiency of 20%, a saturated gain of 77 dB and a 3 dB bandwidth of 2.5 GHz for a 100 kV, 20 A electron beam with an axial velocity spread of {delta}v{sub z}/v{sub z}=5%.

  14. 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.

  15. 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

  16. Gyrotron development for space power beaming

    NASA Technical Reports Server (NTRS)

    Manheimer, Wallace M.

    1989-01-01

    The use of a gyrotron for space power beaming, especially in the form of a lunar orbiting power station is discussed. The advantages of phased array power beaming, output power, and the design of a quasi-optical gyrotron are discussed.

  17. High harmonic terahertz confocal gyrotron with nonuniform electron beam

    NASA Astrophysics Data System (ADS)

    Fu, Wenjie; Guan, Xiaotong; Yan, Yang

    2016-01-01

    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.

  18. 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.

  19. Analysis of oscillation characteristics and optimal conditions for high power operation of Gyrotron FU CW GIII

    SciTech Connect

    Tatematsu, Y. Yamaguchi, Y.; Kawase, T.; Ichioka, R.; Ogawa, I.; Saito, T.; Idehara, T.

    2014-08-15

    The oscillation characteristics of Gyrotron FU CW GIII and its wave frequency and output power dependences on the magnetic field strength, the gun coil current, and the anode voltage were investigated experimentally. The experimental results were analyzed theoretically using a self-consistent code that included the electron properties in the cavity, corresponding to the actual operating conditions in the experiments. As a result, it was found that the variation in frequency with the magnetic field strength was related to an axial profile change in the electromagnetic wave in the cavity. In addition, the optimal condition that gives the maximum output power was found to be determined by the pitch factor rather than by the electron beam radius under the given operating conditions.

  20. High power wideband gyrotron backward wave oscillator operating towards the terahertz region.

    PubMed

    He, W; Donaldson, C R; Zhang, L; Ronald, K; McElhinney, P; Cross, A W

    2013-04-19

    Experimental results are presented of the first successful gyrotron backward wave oscillator (gyro-BWO) with continuous frequency tuning near the low-terahertz region. A helically corrugated interaction region was used to allow efficient interaction over a wide frequency band at the second harmonic of the electron cyclotron frequency without parasitic output. The gyro-BWO generated a maximum output power of 12 kW when driven by a 40 kV, 1.5 A, annular-shaped large-orbit electron beam and achieved a frequency tuning band of 88-102.5 GHz by adjusting the cavity magnetic field. The performance of the gyro-BWO is consistent with 3D particle-in-cell numerical simulations. PMID:23679610

  1. High Power Wideband Gyrotron Backward Wave Oscillator Operating towards the Terahertz Region

    NASA Astrophysics Data System (ADS)

    He, W.; Donaldson, C. R.; Zhang, L.; Ronald, K.; McElhinney, P.; Cross, A. W.

    2013-04-01

    Experimental results are presented of the first successful gyrotron backward wave oscillator (gyro-BWO) with continuous frequency tuning near the low-terahertz region. A helically corrugated interaction region was used to allow efficient interaction over a wide frequency band at the second harmonic of the electron cyclotron frequency without parasitic output. The gyro-BWO generated a maximum output power of 12 kW when driven by a 40 kV, 1.5 A, annular-shaped large-orbit electron beam and achieved a frequency tuning band of 88-102.5 GHz by adjusting the cavity magnetic field. The performance of the gyro-BWO is consistent with 3D particle-in-cell numerical simulations.

  2. Full high-power modulation on a 170 GHz 1 MW ITER gyrotron with a triode magnetron injection gun

    NASA Astrophysics Data System (ADS)

    Kajiwara, K.; Sakamoto, K.; Oda, Y.; Hayashi, K.; Takahashi, K.; Kasugai, A.

    2013-04-01

    A 5 kHz full power modulation experiment is demonstrated on a 170 GHz gyrotron. 5 kHz high-power and beam on/off modulation is achieved by employing a fast short-circuited switch between the anode and the cathode of the triode-type electron gun (single anode switch). Lower heat load on the cavity and the collector compared with continuous-wave operation realizes more than 1 MW oscillation with 1 MW designed gyrotron. The maximum achieved power is 1.16 MW with an electrical efficiency of 48%. In the high-efficiency operation, an unwanted mode oscillation is observed at the start-up phase of each pulse, which is induced by the slow voltage rise time of the anode. For faster rise of the anode voltage, another fast switch is inserted between an anode voltage divider and the anode (double anode switch). In the experiment, successful fast start-up of the anode voltage and minimized unwanted mode generation are observed.

  3. High-harmonic gyrotron with sectioned cavity

    SciTech Connect

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

    2010-07-15

    High-harmonic large-orbit gyrotrons require long-length operating cavities because of both a weak electron-wave coupling and relatively low electron currents. Since diffraction Q factors of such cavities are very high, a large fraction of the radiated power is dissipated in Ohmic losses. A sectioned klystronlike cavity can be a way to combine a long electron-wave interaction region with a relatively low diffraction Q factor. In this paper, a design of a third-harmonic terahertz gyrotron is studied in detail and discussed. As compared to a regular cavity, the use of a sectioned microwave system provides an enhancement of the output rf power by several times along with the halving of the Ohmic losses.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    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.

  5. Self-adjusting anode power supply for a gyrotron

    SciTech Connect

    Brand, G.F.; Fekete, P.W.; Hong, K. ); Idehara, T.; Tatsukawa, T. )

    1991-02-01

    Sydney University's tunable cw gyrotrons use a simplified power supply arrangement to provide the voltages on the gun electrodes. The cathode supply is conventional, but the anode voltage is provided by a single high-value resistor connected between the anode and ground. A small fraction of the electrons in the beam are reflected and the anode automatically finds an optimum operating potential. This arrangement is shown to have lower starting currents. Two advantages follow. It becomes easier to operate low-power gyrotrons with modest power supplies and it becomes easier to achieve higher frequencies by exciting harmonics of the electron cyclotron frequency.

  6. 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.

  7. Influence of Controlled Reflected Power on Gyrotron Performance

    NASA Astrophysics Data System (ADS)

    Kharchev, N.; Cappa, Á.; Malakhov, D.; Martínez, J.; Konchekov, E.; Tolkachev, A.; Borzosekov, V.; Sarksyan, K.; Petelin, M.

    2015-12-01

    This paper describes the reaction of a gyrotron oscillator when a very small fraction of its radiation, extracted from the main beam, is phase-modulated in a controlled way and is finally redirected back to the gyrotron. The gyrotron may exhibit a 10 % modulation of its total power even if the reflected power is lower than 1 %. Moreover, radial probing of the beam power distribution shows that the amplitude of the power modulation differs at different radial positions across the beam.

  8. A generic mode selection strategy for high-order mode gyrotrons operating at multiple frequencies

    NASA Astrophysics Data System (ADS)

    Franck, Joachim; Avramidis, Konstantinos; Gantenbein, Gerd; Illy, Stefan; Jin, Jianbo; Thumm, Manfred; Jelonnek, John

    2015-01-01

    High-power, high-frequency gyrotrons for electron cyclotron resonance heating and current drive, such as proposed for the demonstration thermonuclear fusion reactor DEMO, require operating modes of very high order. As it is shown, the selection of the operating modes for such gyrotrons can be based on multi-frequency operability. A general selection strategy is derived, suitable for multi-purpose multi-frequency gyrotrons with quasi-optical mode converter and single-disc output window. Two examples, one of them relevant for future DEMO gyrotron designs, are discussed.

  9. 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.

  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. High Efficiency Mode Converter for Low-Frequency Gyrotron

    NASA Astrophysics Data System (ADS)

    Minami, Ryutaro; Kariya, Tsuyoshi; Imai, Tsuyoshi; Mitsunaka, Yoshika; Sakamoto, Keishi

    2011-03-01

    A high efficiency quasi-optical (QO) mode converter for high-power, low-frequency gyrotron have been designed and tested. For low-frequency gyrotrons, the scales of the mode converter are comparatively small on the wavelength scale, thus causing significant diffraction losses. Over-1 MW power gyrotron with TE8,3 cavity at 28 GHz have been developed, which has a high efficiency mode converter designed by the use of numerical methods for launcher optimization. This calculation is sufficiently optimized to maximize the fractional Gaussian content of the far field. The total transmission efficiency from the mode converter to output window is 94.7%. For the experimental result of first tube, the output power of more than 1 MW has been obtained with about 40% efficiency and output burn pattern agrees fairly with the calculated profiles, which imply the design appropriateness. Besides, the frequency dependence for diffraction loss is discussed, and these results give the guiding design principle of the mode converter for high-power, low-frequency and long-pulse gyrotrons.

  12. Development of High-Power, Long-Pulse Gyrotrons and Its Application for High Electron Temperature, EBWH and ECCD Experiments on LHD

    SciTech Connect

    Yoshimura, Y.; Kubo, S.; Shimozuma, T.; Igami, H.; Takahashi, H.; Nishiura, M.; Ito, S.; Kobayashi, S.; Mizuno, Y.; Okada, K.; Takita, Y.; Mutoh, T.; Yamada, H.; Komori, A.; Kariya, T.; Imai, T.; Marushchenko, Nikolai B.; Turkin, Yuri

    2011-12-23

    To sustain plasmas with higher parameters and with longer pulse duration in LHD, ECH system has been upgraded by introducing newly developed 77 GHz gyrotrons. The designed output power and operation duration time are over 1 MW for several seconds and 0.3 MW for continuous operation, respectively. Owing to the upgrade of gyrotrons and improved power supply operation procedure, total injection power of EC-waves to LHD increased up to 3.7 MW at the last LHD experimental campaign in 2010.Application of the high-power 77 GHz EC-waves of 3.4 MW as focused beams to the center of plasma with low line-average electron density of {approx}0.2x10{sup 19} m{sup -3} causes highly steep electron temperature profile and the central electron temperature reached up to 20 keV, which highly exceeds the former record of 15 keV. At higher density region of 1x10{sup 19} m{sup -3}, central electron temperature reached 8.6 keV.Additional electron Bernstein wave heatings, O-X-B and slow X-B heatings, using a 77 GHz ECH system caused clear increase in plasma stored energy even for the high-density plasmas over plasma cutoff (>7.35x10{sup 19} m{sup -3}) sustained with NBI. For the O-X-B scenario, the 77 GHz EC-wave was obliquely injected from low-field side in O-mode polarization, aiming at the point where high mode-conversion efficiency was expected. For realizing slow X-B scenario, new inner-vessel mirrors were installed in LHD just close to a helical coil, that is, at the high-field side (HFS) region. Using the inner-vessel mirror, X-mode waves were injected from HFS, showing evident increase in plasma stored energy.Oblique injection of long-pulse 0.77 MW/8 s 77 GHz wave with various N{sub ||} clearly demonstrated ECCD in LHD. The EC-driven current changes its direction with the sign of N{sub ||}, and the highest EC-driven current reached up to 42 kA.

  13. Development of High-Power, Long-Pulse Gyrotrons and Its Application for High Electron Temperature, EBWH and ECCD Experiments on LHD

    NASA Astrophysics Data System (ADS)

    Yoshimura, Y.; Kubo, S.; Shimozuma, T.; Igami, H.; Takahashi, H.; Nishiura, M.; Ito, S.; Kobayashi, S.; Mizuno, Y.; Okada, K.; Takita, Y.; Mutoh, T.; Yamada, H.; Komori, A.; Kariya, T.; Imai, T.; Marushchenko, Nikolai B.; Turkin, Yuri

    2011-12-01

    To sustain plasmas with higher parameters and with longer pulse duration in LHD, ECH system has been upgraded by introducing newly developed 77 GHz gyrotrons. The designed output power and operation duration time are over 1 MW for several seconds and 0.3 MW for continuous operation, respectively. Owing to the upgrade of gyrotrons and improved power supply operation procedure, total injection power of EC-waves to LHD increased up to 3.7 MW at the last LHD experimental campaign in 2010. Application of the high-power 77 GHz EC-waves of 3.4 MW as focused beams to the center of plasma with low line-average electron density of ˜0.2×1019m-3 causes highly steep electron temperature profile and the central electron temperature reached up to 20 keV, which highly exceeds the former record of 15 keV. At higher density region of 1×1019 m-3, central electron temperature reached 8.6 keV. Additional electron Bernstein wave heatings, O-X-B and slow X-B heatings, using a 77 GHz ECH system caused clear increase in plasma stored energy even for the high-density plasmas over plasma cutoff (>7.35×1019 m-3) sustained with NBI. For the O-X-B scenario, the 77 GHz EC-wave was obliquely injected from low-field side in O-mode polarization, aiming at the point where high mode-conversion efficiency was expected. For realizing slow X-B scenario, new inner-vessel mirrors were installed in LHD just close to a helical coil, that is, at the high-field side (HFS) region. Using the inner-vessel mirror, X-mode waves were injected from HFS, showing evident increase in plasma stored energy. Oblique injection of long-pulse 0.77 MW/8 s 77 GHz wave with various N∥ clearly demonstrated ECCD in LHD. The EC-driven current changes its direction with the sign of N∥, and the highest EC-driven current reached up to 42 kA.

  14. Principles of gyrotron powered electromagnetic wigglers for free-electron lasers

    SciTech Connect

    Danly, B.G.; Bekefi, G.; Davidson, R.C.; Temkin, R.J.; Tran, T.M.; Wurtele, J.S.

    1987-01-01

    The operation of free-electron lasers (FEL's) with axial electron beams and high-power electromagnetic wiggler fields such as those produced by high-power gyrotrons is discussed. The use of short wavelength electromagnetic wigglers in waveguides and resonant cavities can significantly reduce required electron beam voltages, resulting in compact FEL's. Gain calculations in the low- and high-gain Compton regime are presented, including the effects of emittance, transverse wiggler gradient, and electron temperature. Optimized scaling laws for the FEL gain and the required electromagnetic wiggler field power are discussed. Several possible configurations for FEL's with electromagnetic wigglers powered by millimeter wavelength gyrotrons are presented. Gyrotron powered wigglers appear promising for operation of compact FEL's in the infrared regime using moderate energy (<10 MeV) electron beams.

  15. Gyrotron development for high-power, long-pulse electron cyclotron heating and current drive at two frequencies in JT-60SA and its extension toward operation at three frequencies

    NASA Astrophysics Data System (ADS)

    Kobayashi, T.; Yokokura, S. Moriyama K.; Sawahata, M.; Terakado, M.; Hiranai, S.; Wada, K.; Sato, Y.; Hinata, J.; Hoshino, K.; Isamaya, A.; Oda, Y.; Ikeda, R.; Takahashi, K.; Sakamoto, K.

    2015-06-01

    A gyrotron enabling high-power, long-pulse oscillations at both 110 and 138 GHz has been developed for electron cyclotron heating (ECH) and current drive (CD) in JT-60SA. Oscillations of 1 MW for 100 s have been demonstrated at both frequencies, for the first time in the world as a gyrotron operating at two frequencies. The optimization of the anode voltage, or the electron pitch factor, using a triode gun was a key to obtain high power and high efficiency at two frequencies. It was also confirmed that the internal losses in the gyrotron were sufficiently low for expected long pulse operation at the higher power level of ∼1.5 MW. Another important result is that an oscillation at 82 GHz, which enables use of fundamental harmonic waves in JT-60SA while the other two frequencies are used as second harmonics waves, was demonstrated up to 0.4 MW for 2 s. These results of the gyrotron development significantly contribute to enhancing the operation regime of the ECH/CD system in JT-60SA.

  16. Integrated Design of Undepressed Collector for Low Power Gyrotron

    NASA Astrophysics Data System (ADS)

    Kumar, Anil; Goswami, Uttam K.; Poonia, Sunita; Singh, Udaybir; Kumar, Nitin; Alaria, M. K.; Bera, A.; Khatun, Hasina; Sinha, A. K.

    2011-06-01

    A 42 GHz, 200 kW continuous wave (CW) gyrotron, operating at TE03 mode is under development for the electron cyclotron resonance plasma heating of the Indian TOKAMAK system. The gyrotron is made up of an undepressed collector. The undepressed collector is simple to design and cost effective. In this paper, a detailed design study of the undepressed collector for the 42 GHz gyrotron is presented. The EGUN code is used to analyze the spent electron beam trajectory for the maximum spread to reduce the power loading on the collector surface. To achieve wall loading ≤1 kW/cm2, a collector with a length of 800 mm and a radius of 42.5 mm is designed. The design also includes the three magnet systems around the collector for maximum and uniform beam spread. The thermal and the structural analyses are done using the ANSYS code to optimize the collector structure and dimensions with tolerance.

  17. Two-tier calibrated electro-optic sensing system for intense field characterization of high-power W-band gyrotron.

    PubMed

    Kim, Seok; Hong, Young-Pyo; Yang, Jong-Won; Lee, Dong-Joon

    2016-05-16

    We present a field-calibrated electro-optic sensing system for measurement of the electric field radiating from a high-power vacuum oscillator at ~95 GHz. The intense electric field is measured in absolute scale via two probe-calibration steps, associated with a photonic heterodyne scheme. First, a micro-electro-optic probe, fabricated to less than one-tenth the oscillation wavelength scale to minimize field-perturbation due to the probe, is placed on the aperture of a field-calculable WR-10 waveguide to calibrate the probe in V/m scale. Then, using this arrangement as a calibrated reference probe at the first-tier position, another probe-bulkier, and thus more robust and sensitive but not accessible to the aperture-is calibrated at the second-tier position away from the waveguide aperture. This two-tier calibrated probe was utilized to diagnose the sub-MV/m scale of intense electric fields and emissions from a high-power W-band gyrotron. The experimental results obtained proved consistent with calculated analytical results-verifying the efficacy of the developed system. PMID:27409877

  18. Measurement of plasma density in the discharge maintained in a nonuniform gas flow by a high-power terahertz-wave gyrotron

    NASA Astrophysics Data System (ADS)

    Sidorov, A. V.; Razin, S. V.; Golubev, S. V.; Safronova, M. I.; Fokin, A. P.; Luchinin, A. G.; Vodopyanov, A. V.; Glyavin, M. Yu.

    2016-04-01

    We performed measurements of plasma density in a "point-like" discharge, which is generated in a nonuniform flow of a gas (argon) under the action of high-power terahertz gyrotron radiation with a frequency of 0.67 THz, a power of 40 kW, and a pulse duration of 20 μs. The nonuniform flow was produced by injecting the gas to the vacuum chamber through a small hole (0.14 mm in diameter) under a background pressure at a level of 0.01 Torr. The discharge developed and was localized only in a small region of space (about 1 mm) near the gas injection hole, where the pressure was high (close to the atmospheric one) and the breakdown conditions (the "point-like" discharge) were fulfilled. The density of electrons in the discharge was measured by observing the Stark broadening of the atomic radiation line Hα of hydrogen (656.3 nm) which was present in the discharge as a minor admixture. The plasma density in the discharge was equal to about 2 × 1016 cm-3, which exceeds the cut-off density for a frequency of 0.67 THz used to maintain the discharge.

  19. Stability of gyrotron operation in very high-order modes

    SciTech Connect

    Sinitsyn, O. V.; Nusinovich, G. S.; Antonsen, T. M. Jr.

    2012-06-15

    This study was motivated by the desire to increase the power, which can be delivered by gyrotrons in long pulse and continuous regimes. Since the admissible power level is determined by the density of ohmic losses in resonator walls, to increase the radiated power a gyrotron should operate in higher order modes. Using an existing gyrotron developed for plasma experiments in the International Thermonuclear Experimental Reactor as a base model, the stability of operation of such a gyrotron in modes with larger number of radial variations was studied. It is shown that the power level achievable in such gyrotrons in stable single mode regimes is close to 1.5 MW. The power level 1.7-1.8 MW can be realized in regimes where the oscillations of the desired mode are accompanied by excitation of distant sidebands whose power is about 1% level of the power of the operating mode. Finally, in the case of operation at the 2-MW level, either the desired mode loses its stability and is replaced by less efficient oscillations of a mode with a smaller azimuthal index or oscillations of the operating mode are accompanied by excitation of sidebands with equally spaced frequencies.

  20. 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.

  1. Start-up scenario of a high-power pulsed gyrotron for 300 GHz band collective Thomson scattering diagnostics in the large helical device

    NASA Astrophysics Data System (ADS)

    Dumbrajs, O.; Saito, T.; Tatematsu, Y.

    2016-02-01

    We present results of theoretical study of mode competition during the voltage rise of a 300-kW, 300-GHz gyrotron operating in the TE22,2,1 mode. Simulations tracking eight competing modes show that, with a proper choice of the magnetic field, stable excitation of the operating mode can be realized, despite the presence of parasitic modes in the resonator spectrum. A finite voltage rise time, 1 kV/4 ns referred to as the slow voltage rise case, is taken into account to simulate realistically the experimental condition. Simulation results with the finite voltage rise time are in good agreement with the experimental test, in which the gyrotron demonstrated reliable operation at power levels up to 300 kW. Moreover, interesting phenomena are observed. Along with voltage rise, the oscillation manner changes from backward wave oscillation to gyrotron oscillation. In the range of the magnetic field lower than the magnetic field strength at which the TE22,2 mode attains to the maximum power, mode competition with the TE21,2 mode takes place although many other competing modes exist in between the two modes. In addition to the slow voltage rise case, the fast voltage rise case, 10 kV/4 ns, and the instant voltage rise case are considered. For these cases, simulations also predict stable oscillation of the TE22,2 mode with the same power level with the slow voltage rise case. This indicates that stable oscillations of the TE22,2 mode can be obtained in a wide range of the voltage rise time.

  2. Low-voltage gyrotrons

    SciTech Connect

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

    2013-03-15

    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).

  3. 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).

  4. 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.

  5. Frequency and phase stabilization of a multimode gyrotron with megawatt power by an external signal

    NASA Astrophysics Data System (ADS)

    Bakunin, V. L.; Denisov, G. G.; Novozhilova, Yu. V.

    2014-05-01

    We have numerically studied capturing of the oscillation frequency and phase of the TE28.12 operating mode by an external monochromatic signal for a multimode gyrotron with a close to real regime of activation. It is shown that, even at a low external-signal power, in a wide range of the magnetic field and voltage, a highly efficient single-mode generating is set at the frequency of the external signal.

  6. 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.

  7. Emittance of short-pulsed high-current ion beams formed from the plasma of the electron cyclotron resonance discharge sustained by high-power millimeter-wave gyrotron radiation

    SciTech Connect

    Razin, S. Zorin, V.; Izotov, I.; Sidorov, A.; Skalyga, V.

    2014-02-15

    We present experimental results on measuring the emittance of short-pulsed (≤100 μs) high-current (80–100 mA) ion beams of heavy gases (Nitrogen, Argon) formed from a dense plasma of an ECR source of multiply charged ions (MCI) with quasi-gas-dynamic mode of plasma confinement in a magnetic trap of simple mirror configuration. The discharge was created by a high-power (90 kW) pulsed radiation of a 37.5-GHz gyrotron. The normalized emittance of generated ion beams of 100 mA current was (1.2–1.3) π mm mrad (70% of ions in the beams). Comparing these results with those obtained using a cusp magnetic trap, it was concluded that the structure of the trap magnetic field lines does not exert a decisive influence on the emittance of ion beams in the gas-dynamic ECR source of MCI.

  8. Emittance of short-pulsed high-current ion beams formed from the plasma of the electron cyclotron resonance discharge sustained by high-power millimeter-wave gyrotron radiation.

    PubMed

    Razin, S; Zorin, V; Izotov, I; Sidorov, A; Skalyga, V

    2014-02-01

    We present experimental results on measuring the emittance of short-pulsed (≤100 μs) high-current (80-100 mA) ion beams of heavy gases (Nitrogen, Argon) formed from a dense plasma of an ECR source of multiply charged ions (MCI) with quasi-gas-dynamic mode of plasma confinement in a magnetic trap of simple mirror configuration. The discharge was created by a high-power (90 kW) pulsed radiation of a 37.5-GHz gyrotron. The normalized emittance of generated ion beams of 100 mA current was (1.2-1.3) π mm mrad (70% of ions in the beams). Comparing these results with those obtained using a cusp magnetic trap, it was concluded that the structure of the trap magnetic field lines does not exert a decisive influence on the emittance of ion beams in the gas-dynamic ECR source of MCI. PMID:24593354

  9. Emittance of short-pulsed high-current ion beams formed from the plasma of the electron cyclotron resonance discharge sustained by high-power millimeter-wave gyrotron radiation

    NASA Astrophysics Data System (ADS)

    Razin, S.; Zorin, V.; Izotov, I.; Sidorov, A.; Skalyga, V.

    2014-02-01

    We present experimental results on measuring the emittance of short-pulsed (≤100 μs) high-current (80-100 mA) ion beams of heavy gases (Nitrogen, Argon) formed from a dense plasma of an ECR source of multiply charged ions (MCI) with quasi-gas-dynamic mode of plasma confinement in a magnetic trap of simple mirror configuration. The discharge was created by a high-power (90 kW) pulsed radiation of a 37.5-GHz gyrotron. The normalized emittance of generated ion beams of 100 mA current was (1.2-1.3) π mm mrad (70% of ions in the beams). Comparing these results with those obtained using a cusp magnetic trap, it was concluded that the structure of the trap magnetic field lines does not exert a decisive influence on the emittance of ion beams in the gas-dynamic ECR source of MCI.

  10. 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.

  11. GYROTRON POWER BALANCE BASED ON CALORIMETRIC MEASUREMENTS IN THE DIII-D ECH SYSTEM

    SciTech Connect

    GORELOV,I.A; LOHR,J.M; BAITY,JR.,F.W; CAHALAN,P; CALLIS,R.W; PONCE,D; CHIU,H.K

    2003-10-01

    OAK-B135 A powerful microwave system operating at the second harmonic of the electron cyclotron frequency on the DIII-D tokamak was upgraded up to six assemblies of 110 GHz gyrotrons in 2003. three Gycom gyrotrons nominally generate 750 kW for 2 s pulses, with the pulse length limit resulting from the peak temperature allowed on the boron nitride rf output window. Three Communications and Power Industries (CPI) gyrotrons with diamond windows have been recently installed and have been tested to 0.9-1.0 MW for 5 s pulses. Heat loading on internal parts of the gyrotrons, the matching optics unit and the dummy loads is measured calorimetrically. This paper discusses the calorimetry system and calorimetric measurements of gyrotron performance.

  12. 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.

  13. Gyrotron: A high-frequency microwave amplifier

    NASA Technical Reports Server (NTRS)

    Kupiszewski, A.

    1979-01-01

    A proposed microwave amplifier mechanism for future generations of millimeter high power uplinks to spacecraft and planetary radar transmitters is introduced. Basic electron-electromagnetic field interaction theory for RF power gain is explained. The starting point for general analytical methods leading to detailed design results is presented.

  14. 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)

  15. Stable, high efficiency gyrotron backward-wave oscillator

    SciTech Connect

    Fan, C. T.; Chang, T. H.; Pao, K. F.; Chu, K. R.; Chen, S. H.

    2007-09-15

    Stability issues have been a major concern for the realization of broadband tunability of the gyrotron backward-wave oscillator (gyro-BWO). Multimode, time-dependent simulations are employed to examine the stability properties of the gyro-BWO. It is shown that the gyro-BWO is susceptible to both nonstationary oscillations and axial mode competition in the course of frequency tuning. Regions of nonstationary oscillations and axial mode competition are displayed in the form of stability maps over wide-ranging parameter spaces. These maps serve as a guide for the identification and optimization of stable windows for broadband tuning. Results indicate that a shorter interaction length provides greater stability without efficiency degradation. These theoretical predictions have been verified in a Ka-band gyro-BWO experiment using both short and long interaction lengths. In the case of a short interaction length, continuous and smooth tunability, in magnetic field and in beam voltage, was demonstrated with the high interaction efficiency reported so far. A maximum 3-dB tuning range of 1.3 GHz with a peak power of 149 kW at 29.8% efficiency was achieved. In a comparative experiment with a longer interaction length, the experimental data are characterized by piecewise-stable tuning curves separated by region(s) of nonstationary oscillations, as predicted by theory.

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

    PubMed

    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. PMID:25638140

  17. Klystron-like cavity with mode transformation for high-harmonic terahertz gyrotrons

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    A novel cavity scheme of a gyrotron is proposed and investigated. As it provides low Ohmic losses and high mode selectivity, it can be especially prospective for realization in gyrotrons operating in the THz frequency range. Numerical simulations show that it allows three-fold increase in the efficiency of the low-relativistic 500 GHz fourth-harmonic gyrotron as compared to conventional two-section scheme with modes transformation.

  18. Klystron-like cavity with mode transformation for high-harmonic terahertz gyrotrons

    SciTech Connect

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

    2013-01-15

    A novel cavity scheme of a gyrotron is proposed and investigated. As it provides low Ohmic losses and high mode selectivity, it can be especially prospective for realization in gyrotrons operating in the THz frequency range. Numerical simulations show that it allows three-fold increase in the efficiency of the low-relativistic 500 GHz fourth-harmonic gyrotron as compared to conventional two-section scheme with modes transformation.

  19. Observation of dynamic interactions between fundamental and second-harmonic modes in a high-power sub-terahertz gyrotron operating in regimes of soft and hard self-excitation.

    PubMed

    Saito, Teruo; Tatematsu, Yoshinori; Yamaguchi, Yuusuke; Ikeuchi, Shinji; Ogasawara, Shinya; Yamada, Naoki; Ikeda, Ryosuke; Ogawa, Isamu; Idehara, Toshitaka

    2012-10-12

    Dynamic mode interaction between fundamental and second-harmonic modes has been observed in high-power sub-terahertz gyrotrons [T. Notake et al., Phys. Rev. Lett. 103, 225002 (2009); T. Saito et al. Phys. Plasmas 19, 063106 (2012)]. Interaction takes place between a parasitic fundamental or first-harmonic (FH) mode and an operating second-harmonic (SH) mode, as well as among SH modes. In particular, nonlinear excitation of the parasitic FH mode in the hard self-excitation regime with assistance of a SH mode in the soft self-excitation regime was clearly observed. Moreover, both cases of stable two-mode oscillation and oscillation of the FH mode only were observed. These observations and theoretical analyses of the dynamic behavior of the mode interaction verify the nonlinear hard self-excitation of the FH mode. PMID:23102316

  20. 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. PMID:24593607

  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. Study of a high-order-mode gyrotron traveling-wave amplifier

    SciTech Connect

    Chiu, C. C.; Tsai, C. Y.; Kao, S. H.; Chu, K. R.; Barnett, L. R.; Luhmann, N. C. Jr.

    2010-11-15

    Physics and performance issues of a TE{sub 01}-mode gyrotron traveling-wave amplifier are studied in theory. For a high order mode, absolute instabilities on neighboring modes at the fundamental and higher cyclotron harmonic frequencies impose severe constraints to the device capability. Methods for their stabilization are outlined, on the basis of which the performance characteristics are examined in a multidimensional parameter space under the marginal stability criterion. The results demonstrate the viability of a high-order-mode traveling-wave amplifier and provide a roadmap for design tradeoffs among power, bandwidth, and efficiency. General trends are observed and illustrated with specific examples.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

    2015-08-01

    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.

  5. 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.

  6. 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

  7. 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. PMID:17404605

  8. Continuous-wave submillimeter-wave gyrotrons

    NASA Astrophysics Data System (ADS)

    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.

    2006-10-01

    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.

  9. Analysis of a high harmonic rectangular gyrotron using ribbon beams

    NASA Technical Reports Server (NTRS)

    Ferendeci, Altan M.

    1989-01-01

    Cylindrical cavity structures and electron orbits; a grooved gyrotron using a ribbon beam; construction details; radiation patterns; radiation distribution; phase distribution; energy curves; and advantages are outlined. This presentation is represented by viewgraphs and charts only.

  10. The reflex gyrotron

    NASA Astrophysics Data System (ADS)

    Goldenberg, A. L.; Savilov, A. V.; Yulpatov, V. K.

    2012-02-01

    A typical problem of low-power short-wavelength gyrotrons is that a too long cavity is required to provide the start of rf oscillations. Therefore, it is attractive to realize a gyrotron with a long enough operating region but relatively low diffraction Q-factor of the operating cavity. In this work, we propose a gyrotron with reflecting of electrons back to the operating cavity. Such a scheme provides significant decrease of the starting current and considerable efficiency enhancement.

  11. Theory and algorithms for a quasi-optical launcher design method for high-frequency gyrotrons

    NASA Astrophysics Data System (ADS)

    Ungku Farid, Ungku Fazri

    Gyrotrons are vacuum tubes that can generate high amounts of coherent high-frequency microwave radiation used for plasma heating, breakdown and current drive, and other applications. The gyrotron output power is not directly usable, and must be converted to either a free-space circular TEM00 Gaussian beam or a HE11 corrugated waveguide mode by employing mode converters. Quasi-optical mode converters (QOMC) achieve this by utilizing a launcher (a type of waveguide antenna) and a mirror system. Adding perturbations to smooth-wall launchers can produce a better Gaussian shaped radiation pattern with smaller side lobes and less diffraction, and this improvement leads to higher power efficiency in the QOMC. The oversize factor (OF) is defined as the ratio of the operating to cutoff frequency of the launcher, and the higher this value is, the more difficult it is to obtain good launcher designs. This thesis presents a new method for the design of any perturbed-wall TE 0n launcher that is not too highly oversized, and it is an improvement over previous launcher design methods that do not work well for highly oversized launchers. This new launcher design method is a fusion of three different methods, which are the Iterative Stratton-Chu algorithm (used for fast and accurate waveguide field propagations), the Katsenelenbaum-Semenov phase-correcting optimization algorithm, and Geometrical Optics. Three different TE02 launchers were designed using this new method, 1) a highly oversized (2.49 OF) 60 GHz launcher as proof-of-method, 2) a highly oversized (2.66 OF) 28 GHz launcher for possible use in the quasihelically symmetric stellarator (HSX) transmission line at the University of Wisconsin -- Madison, and 3) a compact internal 94 GHz 1.54 OF launcher for use in a compact gyrotron. Good to excellent results were achieved, and all launcher designs were independently verified with Surf3d, a method-of-moments based software. Additionally, the corresponding mirror system for

  12. High power millimeter wave source development program

    NASA Technical Reports Server (NTRS)

    George, T. V.

    1989-01-01

    High power millimeter wave sources for fusion program; ECH source development program strategy; and 1 MW, 140 GHz gyrotron experiment design philosophy are briefly outlined. This presentation is represented by viewgraphs only.

  13. 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.

  14. 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.

  15. 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.

  16. Experimental investigation of a coaxial gyrotron oscillator

    NASA Astrophysics Data System (ADS)

    Advani, Rahul N.

    1999-09-01

    This thesis presents experimental results of a megawatt power level, 140 GHz coaxial gyrotron oscillator. The coaxial gyrotron has the potential to transport very high power electron beams and thus achieve higher microwave output power levels than conventional gyrotrons. A TE21,13 coaxial gyrotron was designed to operate at 95 kV, 76 A. This tube was tested to high power with the first high power Inverted Magnetron Injection Gun (IMIG). The IMIG electron gun was tested to 10 MW (105 kV, 93 A), which is the highest power level for a non-relativistic gyrotron gun. Operation of the coaxial gyrotron oscillator yielded power levels of greater than 1 MW in two different configurations: with the coaxial conductor (at 92kV, 70 A, and 16% efficiency) and without the coaxial conductor (85 kV, 65 A, and 18% efficiency). We also successfully operated this tube in three configurations (empty cavity, radial output, and axial output) with no beam interception. We observed regimes of dominant single mode and multi-mode operation. We also identified electron beam asymmetries and tube alignment as two major issues, which can limit the performance of a coaxial gyrotron. An unexpected source of magnetic field error was found in the magnetization of the stainless steel parts. All these results have led to techniques for improving not only coaxial gyrotrons but also other gyrotron tubes. We also investigated a ferroelectric cathode, which has the potential to achieve higher currents than thermionic cathodes in a simpler, low cost gun. We report the first results on a ferroelectric cathode gun in a magnetron injection gun configuration suitable for use in a gyrotron. It had an annular emitter shape with a diameter of 11.4 cm and a width of 0.25 cm and operated at currents of up to 10 A (1.1 A/cm2) at 8 kV, in 5 μs flat-top pulses. This result (along with the kiloampere beam obtained at Integrated Applied Physics) demonstrate the scalability of ferroelectric cathodes to large diameter

  17. 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).

  18. 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.

  19. High efficiency coupling of radio frequency beams from the dual frequency gyrotron with a corrugated waveguide transmission system.

    PubMed

    Oda, Yasuhisa; Kajiwara, Ken; Takahashi, Koji; Mitsunaka, Yoshika; Sakamoto, Keishi

    2013-01-01

    High efficiency coupling of the millimeter-wave output of the dual-frequency gyrotron with the transmission line was demonstrated. The dual-frequency gyrotron was design to produce similar beam profiles for two operation frequencies (170 GHz and 137 GHz). Using two RF beam reflecting mirrors in a matching optics unit (MOU), which are designed to transform the beam profile of the gyrotron output to the fundamental waveguide mode (HE(11) mode) at 170 GHz, high efficiency coupling was demonstrated for two frequencies. The measured mode purity of HE(11) mode was 96% at 170 GHz and 94% at 137 GHz operations with the identical mirrors at the fixed mirror position and angle. The results indicate that the significantly simple dual frequency system is realized by the gyrotron designed to output the similar beam profiles at different frequency operation. PMID:23387644

  20. 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.

  1. High current proton source based on ECR discharge sustained by 37.5 GHz gyrotron radiation

    NASA Astrophysics Data System (ADS)

    Skalyga, V.; Izotov, I.; Sidorov, A.; Razin, S.; Zorin, V.; Tarvainen, O.; Koivisto, H.; Kalvas, T.

    2012-10-01

    Formation of hydrogen ion beams with high intensity and low transverse emittance is one of the key challenges in accelerator technology. Present work is devoted to experimental investigation of proton beam production from dense plasma (Ne > 1013 cm-3) of an ECR discharge sustained by 37.5 GHz, 100 kW gyrotron radiation at SMIS 37 facility at IAP RAS. The anticipated advantages of the SMIS 37 gasdynamic ion source over the current state-of-the-art proton source technology based on 2.45 GHz hydrogen discharges are described. Experimental result obtained with different extraction configurations i.e. single- and multi-aperture systems are presented. It was demonstrated that ultra bright proton beam with approximately 4.5 mA current and 0.03 π·mm·mrad normalized emittance can be produced with the single-aperture (1 mm in diameter) extraction, the corresponding brightness being 5 A/(π·mm·mrad)2. For production of high current beams a multi-aperture extractor was used resulting to a record of 200 mA / 1.1 π·mm·mrad normalized emittance proton beam. The species fraction i.e. the ratio of H+ to H2+ current was recorded to be > 90 % for all extraction systems. A possibility of further enhancement of the beam parameters by improvements of the extraction system and its power supply is discussed.

  2. 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.

  3. 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)

  4. Microwave generation for magnetic fusion energy applications. Task A, Free electron lasers with small period wigglers; Task B, Theory and modeling of high frequency, high power gyrotron operation: Progress report, May 1, 1993--May 1, 1994

    SciTech Connect

    Antonsen, T.M. Jr.; Destler, W.W.; Granatstein, V.; Levush, B.

    1994-05-01

    This task involves the feasibility of high-power pulsed, high- efficiency, millimeter-wave free electron lasers (FEL) for ecr of thermonuclear plasmas. The research undertaken is to develop high average power FEL at voltage below IMV allowing for smaller and less costly power supplies. Linear amplification experiments employing a No. 56 period untapered wiggler have been conducted, and substantial small signal gain was observed at 95 GHz over a wide range of experimental conditions consistent with the prediction of one-dimensional numerical simulation. Progress is also reported on theoretical studies relating to the development of high-power gryotron and the ability to predict and improve the performance of various cavity designs.

  5. 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.

  6. 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.

    PubMed

    Ogasawara, S; Kubo, S; Nishiura, M; Tatematsu, Y; Saito, T; Tanaka, K; Shimozuma, T; Yoshimura, Y; Igami, H; Takahashi, H; Ito, S; Takita, Y; Kobayashi, S; Mizuno, Y; Okada, K; Minami, R; Kariya, T; Imai, T

    2012-10-01

    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(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(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. PMID:23126903

  7. 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.

  8. 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)

  9. High power millimeter wave ECRH source needs for fusion program

    SciTech Connect

    Not Available

    1984-06-01

    This document stems from the four-day Gyrotron Symposium held at the US Department of Energy (DOE) Headquarters on June 13-16, 1983, and serves as a position paper for the Office of Fusion Energy, DOE, on high-power millimeter wave source development for Electron Cyclotron Heating (ECH) of plasmas. It describes the fusion program needs for gyrotron as ECH sources, their current status, and desirable development strategies.

  10. First 200 kW CW operation of a 60 GHz gyrotron

    SciTech Connect

    Jory, H.; Bier, R.; Evans, S.; Felch, K.; Fox, L.; Huey, H.; Shively, J.; Spang, S.

    1983-01-01

    The gyrotron is a microwave tube which employs the electron cyclotron maser interaction to produce high power output at millimeter wavelengths. It has important and growing applications for heating of plasmas in controlled thermonuclear fusion experiments. The Varian 60 GHz gyrotron has recently generated microwave power in excess of 200 kW during CW operation, wth excellent dynamic range and operating stability. This is the highest average power ever produced by a microwave tube in the millimeter wave region. A description of the gyrotron design and test results are presented.

  11. Polarization Issues with High Power Injection and Low Power Emission in Fusion Experiments

    SciTech Connect

    Goodman, T. P.; Felici, F.; Udintsev, V. S.

    2009-11-26

    All tokamak experiments using ECCD require setting of the beam elliptical polarization for proper coupling to the plasma. This is done either in the matching optics unit (MOU) at the output of the gyrotron, or in a couple of miter bends of the transmission line. Similarly, oblique ECE receivers require selection of the correct elliptical polarization to provide localized measurements. For the TCV tokamak at the CRPP, gyrotron and oblique-ECE polarizers are characterized during either high- or low- power testing of equipment: for the gyrotrons the behaviour is determined at a single frequency, but for the oblique-ECE the broadband response is needed. These characteristics are included in the calibration database and used during subsequent analysis of the power coupling to, or from, the sources (gyrotron, plasma, or low power transmitting antenna). A more detailed characterization has been carried out (at low power) with the MOU for the EU, 170 GHz, 2 MW, gyrotron prototype for ITER. This paper discusses the methodology and results of these measurements, as well as a review of nearly a decade's worth of experimental data from the 6 gyrotron, 3 MW, 82.6 GHz TCV system. In particular, the consistency between the calibrations and the subsequent data from tokamak experiments is analysed.

  12. High power local ECH in CHS

    SciTech Connect

    Kubo, S.; Idei, H.; Iwase, M.; Ohkubo, K.; Minami, T.; Yamada, I.; Narihara, K.; Tanaka, K.; Wilgen, J.B.; Murakami, M.; Rasumussen, D.A.; Nishimura, K.; Okamura, S.; Matsuoka, K.

    1996-02-01

    Electron cyclotron heating (ECH) experiments with 200 kW and 400 kW gyrotrons at the frequency of 53.2 GHz have been performed in Compact Helical System (CHS). Microwave power from both gyrotrons is transmitted with quasi-optical transmission line and highly focused on the mid-plane of CHS. The main purpose of these experiments is to understand the heating and energy transport mechanisms in CHS at the low collisional regime. The combination of the magnetic field, focal position and polarization enables the investigation of the on/off axis local heating effect with fundamental and second harmonic ECH. {copyright} {ital 1996 American Institute of Physics.}

  13. 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)

  14. 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.

  15. 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.

  16. Scaling calculations for a relativistic gyrotron. Memorandum report, March 1984-March 1985

    SciTech Connect

    Fliflet, A.W.

    1985-07-31

    The relativistic gyrotron is under development as an ultra-high power source of millimeter-wave radiation. The purpose of the present study is to estimate the optimum operating characteristics of gyrotrons based on multi-kiloampere, mega-electron volt electron beams. Gyrotrons with weakly relativistic, moderate-current electron beams have demonstrated very high efficiency and average power at millimeter wavelengths and the possibility of achieving good efficiencies at very high-peak powers is of interest. Compared to other high-power millimeter-wave generators, gyrotrons are relatively insensitive to electron-beam velocity spread and thus appear well suited to device configurations based on high-current pulseline accelerators. The results of this study indicate that the relativistic gyrotron has potential for achieving high efficiency (15-30%) using relativistic electron beams with gamma approx 2-3. Optimum efficiency occurs for short interaction lengths, characterized by 4-8 cyclotron periods. Such short interaction lengths lead to the possibility of very high peak power generation using multi-kiloampere beams: 100-300 MW with a 600 keV beam and about 1 GW with a 1 MeV beam. The output power risetime has been estimated to be a few nanoseconds for a low-Q oscillator at 35 GHz, which implies the gyrotron interaction can be readily investigated using a 20-100 nsec pulseline accelerator.

  17. Selective suppression of high order axial modes of the gyrotron backward-wave oscillator

    SciTech Connect

    Pao, K. F.; Fan, C. T.; Chang, T. H.; Chiu, C. C.; Chu, K. R.

    2007-09-15

    Selective suppression of high order axial modes of the gyrotron backward-wave oscillator (gyro-BWO) is investigated in theory and in experiment. The gyro-BWO interaction is much more efficient in a down-tapered interaction structure, while it is also more susceptible to the problem of axial mode competition in such a structure. Because higher order axial modes (at a higher oscillation frequency) penetrate deeper into the interaction structure, application of distributed wall loss at the downstream end of the interaction structure is shown to be effective for selective suppression of these modes with minor effects on the efficiency of the desired fundamental axial mode. A stable gyro-BWO operating in a single mode throughout the entire beam pulse is demonstrated on the basis of this principle. Theoretical and experimental results are found to be in good agreement.

  18. Zones of Frequency Locking by an External Signal in a Multimode Gyrotron of a Megawatt Power Level

    NASA Astrophysics Data System (ADS)

    Bakunin, V. L.; Denisov, G. G.; Novozhilova, Yu. V.

    2016-05-01

    We study locking of the oscillation frequency of the operating TE28,12 mode by an external monochromatic signal in a multimode gyrotron operated at a frequency of 170 GHz in the switch-on regime close to the real one. Locking zones, i.e., regions of single-mode generation at the external-signal frequency are found on the "current—detuning" plane of parameters. It is shown that as the number of competing modes increases, the maximum achievable current decreases, and the locking zones contract at sufficiently high currents.

  19. Designing A Mode Converter For Use With A Gyrotron

    NASA Technical Reports Server (NTRS)

    Hoppe, Daniel J.

    1995-01-01

    Report describes process of designing corrugated, circular-cross-section length of waveguide converting input electromagnetic radiation at frequency of 34.5 GHz in TM(11) mode to output radiation in HE(11) mode. TM(11)-mode input radiation supplied by gyrotron generating continuous-wave power of 200 kW at 34.5 GHz in TE(01) mode followed by TE(01)-to-TM(11) mode converter. Together, gyrotron and mode converters constitute prototype high-power transmitter for long-distance free-space communication.

  20. 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.

  1. 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.

  2. Soviet development of gyrotrons. Interim report

    SciTech Connect

    Kassel

    1986-05-01

    This report surveys the development of high power cyclotron-resonance masers (CRM) and gyrotrons in the Soviet Union, based on Soviet open-source literature. It deals with the nature and history of relativistic CRM devices; provides a sequence of the most important issues of gyrotron research and develoment as perceived by Soviet authors; and discusses individual Soviet research groups, the basic organizational units responsible for the CRM and gyrotron research and development. The study suggests, among other things, that high-power relativistic microwave electronics is one of the most successful areas of Soviet RandD. It has maintained a consistent record of significant achievements; it has managed to overcome the systemic weakness of the Soviet RandD system in being able to translate effectively the results of advanced research into production of practical equipment; and it has become the fastest growing area of application of pulsed-power technology, which itself has been for many years the subject of priority development in the USSR.

  3. A Numerical Study on Finite-Bandwidth Resonances of High-Order Axial Modes (HOAM) in a Gyrotron Cavity

    NASA Astrophysics Data System (ADS)

    Sabchevski, Svilen Petrov; Idehara, Toshitaka

    2015-07-01

    Many novel and prospective applications of the gyrotrons as sources of coherent radiation require a broadband and continuous frequency tunability. A promising and experimentally proven technique to achieve it is based on a successive excitation of a sequence of high-order axial modes (HOAM) in the cavity resonator. Therefore, the studies on HOAM are of both theoretical and practical importance and interest. In this paper, we present and discuss the methods and the results of a numerical investigation on the resonances of HOAM in a typical open gyrotron cavity. The simulations have been performed using the existing as well as novel computational modules of the problem-oriented software package GYROSIM (GYROtron SIMulation) for solution of both the homogeneous and the inhomogeneous Helmholtz equation with radiation boundary conditions, which governs the field amplitude along the axis of the resonant structure. The frequency response of the cavity is studied by analyzing several resonance curves (spectral domain analysis) obtained from the numerical solution of the boundary value problem for the inhomogeneous Helmholtz equation with a predefined source term (excitation) by the finite-difference method (FDM). The approach proposed here allows finite-bandwidth resonances of HOAM to be identified and represented on the dispersion diagram of the cavity mode as bands rather than as discrete points, in contrast to the frequently used physical models that neglect the finite width of these resonances. Developed numerical procedures for calculation of the field profiles for an arbitrary frequency and excitation will be embedded in the cold cavity and self-consistent codes of the GYROSIM package in order to study the beam-wave interaction and energy transfer in gyrotron cavities.

  4. Hysteresis and Frequency Tunability of Gyrotrons

    NASA Astrophysics Data System (ADS)

    Dumbrajs, O.; Khutoryan, E. M.; Idehara, T.

    2016-06-01

    We present the first devoted theoretical and experimental study of the hysteresis phenomenon in relation to frequency tunability of gyrotrons. In addition, we generalize the theory describing electron tuning of frequency in gyrotrons developed earlier to arbitrary harmonics. It is found that theoretical magnetic and voltage hysteresis loops are about two times larger than experimental loops. In gyrotrons whose cavities have high quality factors, hysteresis allows one only little to broaden the frequency tunability range.

  5. Development of multi-purpose MW gyrotrons for fusion devices

    NASA Astrophysics Data System (ADS)

    Minami, R.; Kariya, T.; Imai, T.; Numakura, T.; Endo, Y.; Nakabayashi, H.; Eguchi, T.; Shimozuma, T.; Kubo, S.; Yoshimura, Y.; Igami, H.; Takahashi, H.; Mutoh, T.; Ito, S.; Idei, H.; Zushi, H.; Yamaguchi, Y.; Sakamoto, K.; Mitsunaka, Y.; the GAMMA 10 Group

    2013-06-01

    The latest development achievements in the University of Tsukuba of over-1 MW power level gyrotrons required in present-day fusion devices, GAMMA 10, Large Helical Device (LHD), QUEST, Heliotron J and NSTX, are presented. The obtained maximum outputs are 1.9 MW for 0.1 s on the 77 GHz LHD tube and 1.2 MW for 1 ms on the 28 GHz GAMMA 10 one, which are new records in these frequency ranges. In long-pulse operation, 0.3 MW for 40 min at 77 GHz and 0.54 MW for 2 s at 28 GHz are achieved. A new programme of 154 GHz 1 MW development has started for high-density plasma heating in LHD. On the first 154 GHz tube, 1.0 MW for 1 s is achieved. As a next activity of the 28 GHz gyrotron, an over-1.5 MW gyrotron is designed and fabricated to study the multi-MW oscillation. The possibility of 0.4 MW continuous wave and 2 MW level output in operations of a few seconds, after the improvements of output window and mode converter, is shown. Moreover, a new design study of dual-frequency gyrotron at 28 and 35 GHz has started, which indicates the practicability of the multi-purpose gyrotron.

  6. Absolute instabilities in a high-order-mode gyrotron traveling-wave amplifier.

    PubMed

    Tsai, W C; Chang, T H; Chen, N C; Chu, K R; Song, H H; Luhmann, N C

    2004-11-01

    The absolute instability is a subject of considerable physics interest as well as a major source of self-oscillations in the gyrotron traveling-wave amplifier (gyro-TWT). We present a theoretical study of the absolute instabilities in a TE01 mode, fundamental cyclotron harmonic gyro-TWT with distributed wall losses. In this high-order-mode circuit, absolute instabilities arise in a variety of ways, including overdrive of the operating mode, fundamental cyclotron harmonic interactions with lower-order modes, and second cyclotron harmonic interaction with a higher-order mode. The distributed losses, on the other hand, provide an effective means for their stabilization. The combined configuration thus allows a rich display of absolute instability behavior together with the demonstration of its control. We begin with a study of the field profiles of absolute instabilities, which exhibit a range of characteristics depending in large measure upon the sign and magnitude of the synchronous value of the propagation constant. These profiles in turn explain the sensitivity of oscillation thresholds to the beam and circuit parameters. A general recipe for oscillation stabilization has resulted from these studies and its significance to the current TE01 -mode, 94-GHz gyro-TWT experiment at UC Davis is discussed. PMID:15600760

  7. 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.

  8. High-frequency gyrotron scattering diagnostic for instability studies on TARA

    SciTech Connect

    Woskoboinikow, P.; Cohn, D.R.; Gerver, M.; Mulligan, W.J.; Post, R.S.; Temkin, R.J.; Trulsen, J.

    1985-05-01

    A 1- to 10-kW,>30-ms pulsed, narrow linewidth (<1 MHz), 137-GHz gyrotron is being fabricated for collective Thomson scattering plasma diagnostics on the TARA tandem mirror experiment. The drift cyclotron loss cone, the axial loss cone, harmonics of these instabilities, and the ion two stream instability in the TARA plugs will be studied with this diagnostic.

  9. Regions of azimuthal instability in gyrotrons

    SciTech Connect

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

    2012-06-15

    This paper is devoted to the analysis of the instability of operating modes in high-power gyrotrons with cylindrically symmetric resonators. This instability manifests itself in destruction of the azimuthally uniform wave envelope rotating in a gyrotron resonator having a transverse size greatly exceeding the wavelength. The appearance of azimuthally nonuniform solutions can be interpreted as simultaneous excitation of modes with different azimuthal indices. This problem is studied self-consistently, i.e., taking into account the temporal evolution of both the azimuthal and axial structures of the wave envelope. The region of gyrotron operation free from this instability is identified. The efficiency achievable in this region can be only 1%-2% lower than the maximum efficiency. It is also possible to address the difference between the theory of mode interaction developed under assumption that all modes have fixed axial structure and the self-consistent theory presented here. As known, for fixed axial mode profiles, single-mode high-efficiency oscillations remain stable no matter how dense is the spectrum of competing modes, while the self-consistent theory predicts stable high-efficiency operation only when the azimuthal index does not exceed a certain critical value. It is shown that the azimuthal instability found in the self-consistent theory is caused by excitation of modes having axial structures different from that of the desired central mode.

  10. Regions of azimuthal instability in gyrotrons

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    This paper is devoted to the analysis of the instability of operating modes in high-power gyrotrons with cylindrically symmetric resonators. This instability manifests itself in destruction of the azimuthally uniform wave envelope rotating in a gyrotron resonator having a transverse size greatly exceeding the wavelength. The appearance of azimuthally nonuniform solutions can be interpreted as simultaneous excitation of modes with different azimuthal indices. This problem is studied self-consistently, i.e., taking into account the temporal evolution of both the azimuthal and axial structures of the wave envelope. The region of gyrotron operation free from this instability is identified. The efficiency achievable in this region can be only 1%-2% lower than the maximum efficiency. It is also possible to address the difference between the theory of mode interaction developed under assumption that all modes have fixed axial structure and the self-consistent theory presented here. As known, for fixed axial mode profiles, single-mode high-efficiency oscillations remain stable no matter how dense is the spectrum of competing modes, while the self-consistent theory predicts stable high-efficiency operation only when the azimuthal index does not exceed a certain critical value. It is shown that the azimuthal instability found in the self-consistent theory is caused by excitation of modes having axial structures different from that of the desired central mode.

  11. 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. PMID:26302662

  12. 95 GHz gyrotron with ferroelectric cathode.

    PubMed

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

    2012-11-01

    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. PMID:23215293

  13. System using a megawatt class millimeter wave source and a high-power rectenna to beam power to a suspended platform

    DOEpatents

    Caplan, Malcolm; Friedman, Herbert W.

    2005-07-19

    A system for beaming power to a high altitude platform is based upon a high power millimeter gyrotron source, optical transmission components, and a high-power receiving antenna (i.e., a rectenna) capable of rectifying received millimeter energy and converting such energy into useable electrical power.

  14. 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.

  15. 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.

  16. PRACTICAL EXERIENCES WITH THE 6 GYROTRON SYSTEM ON THE DIII-D TOKAMAK

    SciTech Connect

    LOHR,J; CARY,W.P; GORELOV,Y.A; GRUNLOH,H.J; KAJIWARA,K; PEAVY,J.J; PONCE,D; TOOKER,J; CALLIS,R.W

    2003-10-01

    OAK-B135 The gyrotron installation on the DIII-D tokamak now comprises six 110 GHz gyrotrons in the 1 MW class, three manufactured by CPI[1] and three by Gycom [2]. Two tetrode rectifier/modulator/regulator power supplies were constructed to provide power for the CPI gyrotrons. A second system uses three mod/reg tetrodes connected in parallel, which are fed by a dual parallel tetrode mod/reg to power the Gycom tubes. the windowless evacuated transmission lines are up to 100 m in length, with 80% transmission efficiency. Engineering solutions were developed in specific problematic areas encountered in the development of this complex system, including: Gyrotron instability; high voltage circuit instability; gyrotron conditioning; rf beam forming and coupling to waveguide; output window vacuum seals; material control; launcher mechanics and diagnosis; polarizer mechanics; dummy loads; power measurements; polarization measurements; cooling; calorimetry; and operating controls. The system is in routine operation in support of tokamak experiments, with peak generated power of about 5 MW at 2 s. pulse length and about 3 MW for 5 s. pulses. This presentation focuses on practical lessons learned in the development and operation of these systems.

  17. 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.

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    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.

  20. Design of a multistage depressed collector system for 1 MW CW gyrotrons. Part 2: System consideration

    SciTech Connect

    Ives, R.L.; Mizuhara, M.; Schumacher, R.; Neilson, J. ); Singh, A.; Granatstein, V.L. . Inst. for Plasma Research); Gaudreau, M.; Casey, J.A. )

    1999-04-01

    Part 2 describes the basic mechanical design of the two-stage collector, including the thermal performance. The design should be applicable to Gaussian mode gyrotrons over a very broad frequency range at power levels up to one megawatt CW. Part 2 also describes an innovative regenerative power supply system that utilizes highly efficient, solid state, switching technology that provides high reliability and significantly reduced cost over conventional technology. An advanced computer control system that will provide user-friendly gyrotron operation and allow modes of operation not possible with manual operation is also being developed.

  1. 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.

  2. 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. PMID:22743211

  3. 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.

  4. 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

  5. Single-stage depressed collectors for gyrotrons

    SciTech Connect

    Piosczyk, B.; Iatrou, C.T.; Dammertz, G.; Thumm, M. |

    1996-06-01

    Two 140 GHz gyrotrons with a single-step depressed collector have been operated. The different position of the isolating collector gap in the stray magnetic field causes the electron motion in the retarding region to be in one case adiabatic and in the other case nonadiabatic. The kind of motion within the retarding field influences strongly the behavior of the gyrotron with a depressed collector. In the case of nonadiabatic motion a significant amount of transverse momentum is given to the electrons reflected at the collector potential. This causes the reflected electrons to be trapped between the magnetic mirror and the collector. The electrons escape from the trap by diffusion across the magnetic field to the body of the tube thus contributing to the body current. Despite the high body current there is no observable influence of the collector voltage on the RF output power. In the case of adiabatic motion the reflected electrons do not gain a sufficient amount of transverse momentum to be trapped by the magnetic mirror. They pass the cavity toward the gun and they are trapped between the negative gun potential and the collector. The interaction with the RF field by electrons traveling through the cavity enhances the diffusion in the velocity space thus enabling the trapped electrons to overcome the potential barrier and escape toward the collector. Therefore the body current stays at low values since in this case the reflected electrons do not contribute to it. However, at higher collector voltages a reduction of RF power occurred and some noise in the electron beam was observed. The main motivation for the development of gyrotrons in the frequency range above 100 GHz with power levels in excess of several hundreds kW per tube, is the application in magnetic fusion devices for plasma heating and for electron current drive.

  6. 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.

  7. High-power Ka-band amplifier

    NASA Technical Reports Server (NTRS)

    Cormier, R.

    1993-01-01

    Development of a high-power tube suitable to power a Ka-band (34.5-GHz) antenna transmitter located at the Goldstone, California, tracking station is continuing. The University of Maryland Laboratory for Plasma Research and JPL are conducting a joint effort to test the feasibility of phase locking a second-harmonic gyrotron both by direct injection at the output cavity and by using a priming cavity to bunch the electrons in the beam. This article describes several design options and the results of computer simulation testing.

  8. Studies of a Gyrotron with the Echelette Cavity

    NASA Astrophysics Data System (ADS)

    Belousov, V. I.; Vlasov, S. N.; Zavolsky, N. A.; Zapevalov, V. E.; Koposova, E. V.; Kornishin, S. Yu.; Kuftin, A. N.; Moiseev, M. A.; Khizhnyak, V. I.

    2014-11-01

    We describe a gyrotron which is operated at the first gyrofrequency harmonic and has an echelette cavity with the sinusoidal corrugation profile. A method for calculating the parameters of the echelette cavity and the gyrotron is described. The results of measuring the electrodynamic characteristics of the echelette cavity and studying experimentally the gyrotron with such a cavity are presented. It is shown that the gyrotron has a rarefied spectrum of eigenoscillations and the efficiency at the level of typical megawatt-power gyrotrons, and is characterized by a significantly lower degree of cavity wall heating. The structure of radiation from the gyrotron with the echelette cavity and the possibility of transmitting this radiation by means of a mirror waveguide, are discussed.

  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. Megawatt, 1kHz PRF tunable gyrotron experiments

    SciTech Connect

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

    1995-12-31

    Repetitively pulsed and cw gyrotrons have hitherto used thermionic cathodes whereas cold cathode gyrotrons have normally operated as {open_quote} single shot{close_quote} or low pulse repetition frequency (PRF) devices. The novel results presented here demonstrate that a stacked Blumlein pulse generator driven cold cathode gyrotron developing > 1 MW per pulse (f=90 GHz) may be run with a repetition frequency of 1 kHz over timescales of >30 seconds. A short burst PRF of 2 kHz was also observed. The PRF of the system was limited to 2 kHz by the High Voltage (HV) DC power supply. The gyrotron was based on a two-electrode configuration comprising of 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 stacked Blumlein pulse generator was used to drive the electron beam. This pulse generator was capable of producing an output voltage up to 300 kV with a 20ns rise time, a 100ns flat top, and a 20ns fall time. The output impedance was 200{Omega} and the energy stored in the generator at a charging voltage of 60 kV was 5.4J. No degradation effects on the mm-wave output was evident due to diode recovery time throughout this series of results. A subsequent conclusion is that the recovery time in the cold cathode gyrotron is less than 500{mu}s.

  11. A Brief Technology Survey of High-Power Microwave Sources

    SciTech Connect

    BACON,LARRY D.; RINEHART,LARRY F.

    2001-04-01

    This report provides a brief summary of the characteristics of contemporary high-power microwave sources. The focus is on their physical and operational characteristics and regions of application rather than their theory of operation. Magnetrons, linear beam tubes, split-cavity oscillators, virtual cathode oscillators, gyrotrons, free-electron lasers, and orbitron microwave masers are described. Power supply requirements and engineering issues of the application of HPM devices are addressed.

  12. Frequency measurements of the gyrotrons used for collective Thomson scattering diagnostics at TEXTOR and ASDEX Upgrade

    SciTech Connect

    Woskov, P.; Bindslev, H.; Leipold, F.; Meo, F.; Nielsen, S. K.; Tsakadze, E. L.; Korsholm, S. B.; Scholten, J.; Tito, C.; Westerhof, E.; Oosterbeek, J. W.; Leuterer, F.; Monaco, F.; Muenich, M.; Wagner, D.

    2006-10-15

    High resolution frequency measurements of the 110 GHz gyrotron at TEXTOR and the 105 GHz mode of the two-frequency gyrotron (Odissey-1) at ASDEX Upgrade (AUG) have been made in support of fast ion collective Thomson scattering diagnostics. Measurements were done by harmonic heterodyne methods using both fast Fourier transform spectroscopy with digital oscilloscopes and fast scanning spectrum analyzers. Accurate frequencies were obtained with a frequency counter. At TEXTOR, at 180 kW forward power the starting frequency was 109.970{+-}0.005 GHz and chirped down as much as 27 MHz depending on the duty factor. At AUG, at 500 kW forward power the frequency started at 104.786 GHz and chirped down 104 MHz, with 90% of the chirp occurring in the first 100 ms. Plasma perturbation of the TEXTOR gyrotron was observed when both ion cyclotron resonance heating antennas and neutral beam injection were operating, producing modulation at 29 and 58 MHz in the gyrotron output. Each gyrotron was observed to have an instrumental measurement limited linewidth of 120 kHz full width at half maximum.

  13. 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.

  14. High-Power Microwave Transmission and Mode Conversion Program

    SciTech Connect

    Vernon, Ronald J.

    2015-08-14

    This is a final technical report for a long term project to develop improved designs and design tools for the microwave hardware and components associated with the DOE Plasma Fusion Program. We have developed basic theory, software, fabrication techniques, and low-power measurement techniques for the design of microwave hardware associated gyrotrons, microwave mode converters and high-power microwave transmission lines. Specifically, in this report we discuss our work on designing quasi-optical mode converters for single and multiple frequencies, a new method for the analysis of perturbed-wall waveguide mode converters, perturbed-wall launcher design for TE0n mode gyrotrons, quasi-optical traveling-wave resonator design for high-power testing of microwave components, and possible improvements to the HSX microwave transmission line.

  15. 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.

  16. Design of a Compact Sub-Terahertz Gyrotron for Spectroscopic Applications

    NASA Astrophysics Data System (ADS)

    Sabchevski, Svilen Petrov; Idehara, Toshitaka

    2010-08-01

    In this paper we present the initial design of a novel and versatile high frequency gyrotron with parameters suitable for application to various spectroscopic studies that require coherent radiation in the subterahertz frequency range (such as NMR/DNP spectroscopy, ESR spectroscopy, spectrometer based on the X-ray detected magnetic resonance etc.). The most characteristic feature of the design is that it utilises a compact, cryogen-free 8 T superconducting magnet. As a result, the overall dimensions of the entire device are considerably reduced in comparison with the previously developed tubes belonging to the Gyrotron FU and Gyrotron FU CW series. This makes the novel gyrotron highly portable to diverse laboratory environments and easily embeddable to different measuring systems. The electron-optical system (EOS) of the tube is based on a compact low-voltage magnetron injection gun (MIG), which has been specially designed and optimized together with the resonant cavity using our problem-oriented software package GYROSIM for CAD of gyrotrons. The tube operates at the second harmonic of the cyclotron frequency and generates a radiation with an output power of about 100 W and a frequency tunable up to around 424 GHz, respectively.

  17. 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

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

    PubMed

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

    2013-12-01

    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

  19. High power test of a wideband diplexer with short-slotted metal half mirrors for electron cyclotron current drive system

    SciTech Connect

    Saigusa, M.; Atsumi, K.; Yamaguchi, T.; Nagashima, K.; Oda, Y.; Fukunari, M.; Sakamoto, K.

    2014-02-12

    The wideband high power diplexer has been developed for combining and fast switching of high power millimeter waves generated by a dual frequency gyrotron. The actual diplexer was tested at the frequency band of 170 GHz in low power. After adjusting a resonant frequency of diplexer for the gyrotron frequency, the evacuated wideband diplexer with short-slotted metal half mirrors was tested at an incident power of about 150 kW, a pulse duration of 30 ms and a frequency band of 170.2–170.3 GHz. Any discharge damage was not observed in the diplexer.

  20. High power test of a wideband diplexer with short-slotted metal half mirrors for electron cyclotron current drive system

    NASA Astrophysics Data System (ADS)

    Saigusa, M.; Atsumi, K.; Yamaguchi, T.; Nagashima, K.; Oda, Y.; Fukunari, M.; Sakamoto, K.

    2014-02-01

    The wideband high power diplexer has been developed for combining and fast switching of high power millimeter waves generated by a dual frequency gyrotron. The actual diplexer was tested at the frequency band of 170 GHz in low power. After adjusting a resonant frequency of diplexer for the gyrotron frequency, the evacuated wideband diplexer with short-slotted metal half mirrors was tested at an incident power of about 150 kW, a pulse duration of 30 ms and a frequency band of 170.2-170.3 GHz. Any discharge damage was not observed in the diplexer.

  1. 28 GHz Gyrotron ECRH on LDX

    NASA Astrophysics Data System (ADS)

    Woskov, P. P.; Kesner, J.; Michael, P. C.; Garnier, D. T.; Mauel, M. E.

    2010-12-01

    A 10 kW, CW, 28 GHz gyrotron has been implemented on LDX to increase the plasma density and to more fully explore the potential of high beta plasma stability in a dipole magnetic configuration. This added power represents about a 60% increase in ECRH to a new total of 26.9 kW with sources at 2.45, 6.4, and 10.5 GHz. The 1 Tesla resonances in LDX form small rings encompassing the entire plasma cross-section above and below the floating coil (F-coil) near the dipole axial region. A 32.5 mm diameter TE01 waveguide with a partial Vlasov step cut launches a diverging beam from above the F-coil that depends on internal wall reflections for plasma coupling. Initial gyrotron only plasmas exhibit steep natural profiles with fewer hot electrons than with the other sources. The background scattered radiation suggests that only about half the power is being absorbed with the present launcher.

  2. 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

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

    PubMed

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

    2007-02-01

    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 TE(2) (,) (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

  4. 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.

  5. Subterahertz gyrotron developments for collective Thomson scattering in LHD.

    PubMed

    Notake, T; Saito, T; Tatematsu, Y; Kubo, S; Shimozuma, T; Tanaka, K; Nishiura, M; Fujii, A; Agusu, La; Ogawa, I; Idehara, T

    2008-10-01

    Collective Thomson scattering (CTS) is expected to provide the spatially resolved velocity distribution functions of not only thermal and tail ions but also alpha particles resulting from fusion reactions. CTS using gyrotrons with frequency higher than the conventional ones used for plasma heating would have advantages to alleviate refraction, cutoff effects, and background electron cyclotron emission noise. Therefore, a high-power pulse gyrotron operating at approximately 400 GHz is being developed for CTS in Large Helical Device (LHD). A single-mode oscillation with a frequency greater than 400 GHz, applying the second-harmonic resonance, was successfully demonstrated in the first stage. At the same time, concrete feasibility study based on ray tracing, scattering spectra, and electron cyclotron emission calculations has been conducted. PMID:19044548

  6. Subterahertz gyrotron developments for collective Thomson scattering in LHD

    SciTech Connect

    Notake, T.; Saito, T.; Tatematsu, Y.; Fujii, A.; Agusu, La; Ogawa, I.; Idehara, T.; Kubo, S.; Shimozuma, T.; Tanaka, K.; Nishiura, M.

    2008-10-15

    Collective Thomson scattering (CTS) is expected to provide the spatially resolved velocity distribution functions of not only thermal and tail ions but also alpha particles resulting from fusion reactions. CTS using gyrotrons with frequency higher than the conventional ones used for plasma heating would have advantages to alleviate refraction, cutoff effects, and background electron cyclotron emission noise. Therefore, a high-power pulse gyrotron operating at approximately 400 GHz is being developed for CTS in Large Helical Device (LHD). A single-mode oscillation with a frequency greater than 400 GHz, applying the second-harmonic resonance, was successfully demonstrated in the first stage. At the same time, concrete feasibility study based on ray tracing, scattering spectra, and electron cyclotron emission calculations has been conducted.

  7. Study on Low-Frequency Oscillations in a Gyrotron Using a 3D CFDTD PIC Method

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

    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. 2D Particle-in-cell simulations quasi-statically model the development of oscillations of the space charge in the adiabatic trap, but the physics of the electron dynamics in the adiabatic trap is only partially understood. Therefore, 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 high average power gyrotron. As the CFDTD method exhibits a second order accuracy, complicated structures, such as a magnetron injection gun, can be well described. Employing a highly parallelized computation, the model can be simulated in time domain more realistically.

  8. 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.

  9. A quasi-optical resonant ring for high power millimeter-wave testing

    SciTech Connect

    Bigelow, T.S.

    1997-08-01

    Gyrotrons of > 1-MW cw power in the 110- to 160-GHz frequency range with HE{sub 11} output beams are being developed for electron cyclotron heating (ECH) of plasmas. Windows are required for gyrotrons and for waveguide transmission systems at the plasma device to provide vacuum isolation and containment. Windows ar difficult to build for these systems because the window dielectric losses increase with frequency and the centrally peaked output power beam concentrates the power deposition near the center. Development and testing of a window independent of gyrotron development is desirable since window failure on a cw gyrotron usually means an expensive reprocessing of the entire tube or possibly even total loss. A quasi-optical resonant ring is being developed for testing of millimeter wave components, windows and low-loss materials at very high power levels using medium power level sources. The resonant ring generates a traveling wave resonance of uniform amplitude along the waveguide that is ideal for testing components and materials. Both smooth-wall TE{sub 01} mode and a corrugated-wall HE{sub 11} mode versions have been constructed. These units use highly oversized waveguide and four miter bends to form a quasi-optical resonant ring. A perforated plate miter bend serves as the input directional coupler. A water-cooled tube array is being designed for a coupler capable high-power cw operation. A theoretical power gain of > 10 is possible using the 63.5 mm HE{sub 11} version at 53 GHz. Low power measurements have been performed to confirm the operation and > 1.5 MW high power tests using a 200 kW gyrotron are expected in the near future.

  10. 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.

  11. Continuous-Wave Operation of a 460-GHz Second Harmonic Gyrotron Oscillator.

    PubMed

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

    2006-06-01

    We report the regulated continuous-wave (CW) operation of a second harmonic gyrotron oscillator at output power levels of over 8 W (12.4 kV and 135 mA beam voltage and current) in the TE(0,6,1) mode near 460 GHz. The gyrotron also operates in the second harmonic TE(2,6,1) mode at 456 GHz and in the TE(2,3,1) fundamental mode at 233 GHz. CW operation was demonstrated for a one-hour period in the TE(0,6,1) mode with better than 1% power stability, where the power was regulated using feedback control. Nonlinear simulations of the gyrotron operation agree with the experimentally measured output power and radio-frequency (RF) efficiency when cavity ohmic losses are included in the analysis. The output radiation pattern was measured using a pyroelectric camera and is highly Gaussian, with an ellipticity of 4%. The 460-GHz gyrotron will serve as a millimeter-wave source for sensitivity-enhanced nuclear magnetic resonance (dynamic nuclear polarization) experiments at a magnetic field of 16.4 T. PMID:17710187

  12. Continuous-Wave Operation of a 460-GHz Second Harmonic Gyrotron Oscillator

    PubMed Central

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

    2007-01-01

    We report the regulated continuous-wave (CW) operation of a second harmonic gyrotron oscillator at output power levels of over 8 W (12.4 kV and 135 mA beam voltage and current) in the TE0,6,1 mode near 460 GHz. The gyrotron also operates in the second harmonic TE2,6,1 mode at 456 GHz and in the TE2,3,1 fundamental mode at 233 GHz. CW operation was demonstrated for a one-hour period in the TE0,6,1 mode with better than 1% power stability, where the power was regulated using feedback control. Nonlinear simulations of the gyrotron operation agree with the experimentally measured output power and radio-frequency (RF) efficiency when cavity ohmic losses are included in the analysis. The output radiation pattern was measured using a pyroelectric camera and is highly Gaussian, with an ellipticity of 4%. The 460-GHz gyrotron will serve as a millimeter-wave source for sensitivity-enhanced nuclear magnetic resonance (dynamic nuclear polarization) experiments at a magnetic field of 16.4 T. PMID:17710187

  13. Cold testing of quasi-optical mode converters using a generator for non-rotating high-order gyrotron modes.

    PubMed

    Kim, S G; Kim, D S; Choe, M S; Lee, W; So, J; Choi, E M

    2014-10-01

    In this paper, we test the performance of a quasi-optical, internal-gyrotron mode converter. When cold testing mode converters, a rotating higher-order mode is commonly used. However, this requires a nontrivial design and precise alignment. We thus propose a new technique for testing gyrotron mode converters by using a simple, non-rotating, higher-order mode generator. We demonstrate the feasibility of this technique for a W-band gyrotron quasi-optical mode converter by examining the excitation of a TE6,2 mode from a non-rotating mode generator. Our results demonstrate that this new cold-test scheme is an easy and efficient method for verifying the performance of quasi-optical mode converters. PMID:25362436

  14. 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

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

    PubMed

    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

  16. Silicon with extra low losses for megawatt output gyrotron windows

    SciTech Connect

    Parshin, V.V.; Heidinger, R.; Andreev, B.A.; Gusev, A.V.; Shmagin, V.B.

    1995-12-31

    The dielectric losses are investigated in high-purity grades of silicon doped by different ways to reduce their mm-wave absorption. The results of the dielectric loss tangent measurements are given for the frequency range of 30 - 330 GHz and for the temperature interval 30-330K. The obtained data are discussed together with the thermophysical properties with respect to the power transmission capabilitity of edge-cooled output windows for high power gyrotrons and the potential of the special silicon grades are demonstrated for these applications.

  17. 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.

  18. 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.

  19. Phase locking of a second harmonic gyrotron using a quasi-optical circulator

    NASA Astrophysics Data System (ADS)

    Hoppe, Daniel J.; Perez, Raul M.; Bhanji, Alaudin M.; Guo, Hezhong Z.; Rogers, John; Tate, Jeffrey P.

    1995-09-01

    Phase locking of a high power pulsed gyrotron oscillator through the use of a quasi-optical circulator was investigated. A second harmonic gyrotron which features a novel complex cavity, operating at 34.5 GHz, was used in the experiment. The quasi-optical circulator consisted of a 5.75 inch diameter ferrite disk biased with a one kilogauss permanent magnet. A polarizing grid was used to separate the input and output signals in the circulator. In order to couple the gyrotron oscillator output efficiently to the quasi-optical system, a number of mode converters, TE03-TE02, TE02-TE01, TE01-TM11, and TM11-HE11, were required. The insertion loss of the circulator and mode converter chain was approximately 1 dB, and an isolation exceeding 25 dB was achieved. In addition, a low power WR28 waveguide isolator was inserted in the injection signal path, providing an additional 35 dB of isolation, for a total isolation of 60 dB. The injection signal was provided by a synthesized signal generator and a 100 Watt traveling wave tube amplifier. A sample of the gyrotron output signal was obtained through an additional horn and mixed with a sample of the injection signal, producing a difference signal. The injection signal was swept slowly through a known frequency range while the difference signal was recorded. The recorded signals were analyzed off-line, and the locking bandwidth was determined. Experiments were performed for injection powers from 0-60 Watts, and a gyrotron output power of approximately 80-100 kW. Phase locking was observed for all non-zero injection powers.

  20. Contributions to resolving issues impeding the operation of high power microwave devices

    NASA Astrophysics Data System (ADS)

    Kashyn, Dmytro

    This thesis reports an experimental study aimed at extending high power, high efficiency gyrotron operation to submillimeter wavelengths. A series of experiments carried out both at the University of Maryland and the Institute of Applied Physics of the Russian Academy of Science, succeeded in demonstrating output power at 670 GHz of 180 kilowatts with 20% efficiency (gyrotron voltage was 57 kV and beam current was 16 amperes). The maximum output power achieved in the experiments was 210kW at somewhat higher voltage and current (viz. 58kV and 22A). The achieved output power and efficiency are twice as large as achieved in previous experiments in this frequency range with pulse duration in the range of tens of microseconds. These performance parameters are relevant to a previously proposed application of detecting concealed radioactive materials by air breakdown in a focused beam of sub-millimeter radiation. The 670 GHz gyrotron combined features of two lines of previous experiments: (a) to operate at the required frequency, pulsed solenoids producing 28T magnetic were employed and (b) to obtain high efficiency a very high order mode was used in the gyrotron cavity, as in the experiments with gyrotrons for plasma heating. Evidence of multimode beating was observed in submillimeter output envelope. The excitation of spurious modes, especially during the rise of the gyrotron voltage pulse, was analyzed and the method of avoiding this was proposed which also allows to reduce collector loading in gyrotrons operating in modulated regimes. The present study also includes theoretical analysis of the processes that deepens the understanding of microwave breakdown (arcing) in high power microwave devices. The effect of the dust particles microprotrusions on the device operation was analyzed. These microprotrusions were observed and their negative effects were remedied by careful polishing and machining of the resonator surface. Finally, the generated 670 GHz radiation was

  1. Mode competition effects in free electron lasers and gyrotrons

    SciTech Connect

    Levush, B.; Antonsen, T.M.

    1990-01-01

    In many cases in high frequency, high power coherent radiation generators (such as free electron laser and gyrotrons) the linear gain is positive for many modes and therefore these modes will grow and compete for the beam energy. The questions related to mode competition, coherency of the radiation and maximization of the interaction efficiency are of great importance. To address these issues simple multi-mode models have been formulated. This paper is a short review of the recent results from both simulation and analyses of these models. 3 figs.

  2. 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.

  3. 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.

  4. Active heater control and regulation for the Varian VGT-8011 gyrotron

    SciTech Connect

    Harris, T.E.

    1991-10-01

    The Varian VGT-8011 gyrotron is currently being used in the new 110 GHz 2 MW ECH system installed on D3-D. This new ECH system augments the 60 GHz system which uses Varian VA-8060 gyrotrons. The new 110 GHz system will be used for ECH experiments on D3-D with a pulse width capability of 10 sec. In order to maintain a constant RF outpower level during long pulse operation, active filament-heater control and regulation is required to maintain a constant cathode current. On past D3-D experiments involving the use of Varian VA-8060 gyrotrons for ECH power, significant gyrotron heater-emission depletion was experienced for pulse widths > 300 msec. This decline in heater-emission directly results in gyrotron-cathode current droop. Since RF power from gyrotrons decreases as cathode current decreases, it is necessary to maintain a constant cathode current level during gyrotron pulses for efficient gyrotron operation. Therefore, it was determined that a filament-heater control system should be developed for the Varian VGT-8011 gyrotron which will include cathode-current feed-back. This paper discusses the mechanisms used to regulate gyrotron filament-heater voltage by using cathode-current feed-back. 1 fig.

  5. Activities on Realization of High-Power and Steady-State ECRH System and Achievement of High Performance Plasmas in LHD

    SciTech Connect

    Shimozuma, T.; Kubo, S.; Yoshimura, Y.; Igami, H.; Takahashi, H.; Ikeda, R.; Tamura, N.; Kobayashi, S.; Ito, S.; Mizuno, Y.; Takita, Y.; Mutoh, T.; Minami, R.; Kariya, T.; Imai, T.; Idei, H.; Shapiro, M. A.; Temkin, R. J.; Felici, F.; Goodman, T.

    2009-11-26

    Electron Cyclotron Resonance Heating (ECRH) has contributed to the achievement of high performance plasma production, high electron temperature plasmas and sustainment of steady-state plasmas in the Large Helical Device (LHD). Our immediate targets of upgrading the ECRH system are 5 MW several seconds and 1 MW longer than one hour power injection into LHD. The improvement will greatly extend the plasma parameter regime. For that purpose, we have been promoting the development and installation of 77 GHz/1-1.5 MW/several seconds and 0.3 MW/CW gyrotrons in collaboration with University of Tsukuba. The transmission lines are re-examined and improved for high and CW power transmission. In the recent experimental campaign, two 77 GHz gyrotrons were operated. One more gyrotron, which was designed for 1.5 MW/2 s output, was constructed and is tested. We have been promoting to improve total ECRH efficiency for efficient gyrotron-power use and efficient plasma heating, e.g. a new waveguide alignment method and mode-content analysis and the feedback control of the injection polarization. In the last experimental campaign, the 77 GHz gyrotrons were used in combination with the existing 84 GHz range and 168 GHz gyrotrons. Multi-frequency ECRH system is more flexible in plasma heating experiments and diagnostics. A lot of experiments have been performed in relation to high electron temperature plasmas by realization of the core electron-root confinement (CERC), electron cyclotron current drive (ECCD), Electron Bernstein Wave heating, and steady-state plasma sustainment. Some of the experimental results are briefly described.

  6. Moment-based, self-consistent linear analysis of gyrotron oscillators

    SciTech Connect

    Braunmueller, F. Tran, T. M.; Alberti, S.; Hogge, J.-Ph.; Tran, M. Q.

    2014-04-15

    A new model for simulating gyrotron oscillators in the monomode time-dependent linear self-consistent regime is presented. Starting from a nonlinear time-dependent monomode model, the linearization and the following simplification of the model, based on a moment approach, are described. This simplified model represents a numerically efficient model and allows to have a deeper physical insight, in particular, for regimes dominated by self-consistent effects such as for the gyro-backward wave instability. One specific case of a gyrotron cavity is studied in detail and compared with experimental results, with special attention to self-consistent effects and to the differences with a model using a fixed field profile. Self-consistent linear simulations are, amongst other applications, important for the design of frequency-tunable gyrotrons or high-power gyrotrons with cavities having a relatively low quality factor, but also for studies of parasitic oscillations as they may occur in beam ducts and/or in the launcher section following the interaction cavity.

  7. Moment-based, self-consistent linear analysis of gyrotron oscillators

    NASA Astrophysics Data System (ADS)

    Braunmueller, F.; Tran, T. M.; Alberti, S.; Hogge, J.-Ph.; Tran, M. Q.

    2014-04-01

    A new model for simulating gyrotron oscillators in the monomode time-dependent linear self-consistent regime is presented. Starting from a nonlinear time-dependent monomode model, the linearization and the following simplification of the model, based on a moment approach, are described. This simplified model represents a numerically efficient model and allows to have a deeper physical insight, in particular, for regimes dominated by self-consistent effects such as for the gyro-backward wave instability. One specific case of a gyrotron cavity is studied in detail and compared with experimental results, with special attention to self-consistent effects and to the differences with a model using a fixed field profile. Self-consistent linear simulations are, amongst other applications, important for the design of frequency-tunable gyrotrons or high-power gyrotrons with cavities having a relatively low quality factor, but also for studies of parasitic oscillations as they may occur in beam ducts and/or in the launcher section following the interaction cavity.

  8. 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

  9. 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

  10. The 10-100 kW submillimeter gyrotron

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    High frequency high harmonic gyrotrons; cyclotron autoresonance maser (CARM); CARM amplifier schematics; MIT electron gun; and baseline design for the 140 GHz CARM amplifier are briefly reviewed. This presentation is represented by viewgraphs only.

  11. New results and applications for the quasioptical gyrotron

    NASA Astrophysics Data System (ADS)

    Fliflet, A. W.; Fischer, R. P.; Manheimer, W. M.

    1993-02-01

    The quasioptical gyrotron (QOG), which features an open resonator formed by a pair of spherical mirrors instead of the conventional gyrotron waveguide cavity, has been under development at the U.S. Naval Research Laboratory as a tunable high power millimeterwave source for tokamak plasma heating, advanced radars, and power beaming. In the free running oscillator configuration, the QOG has produced a peak power of 6OOkW at a frequency of 120GHZ, and a peak efficiency of 12% at 200kW. Results have recently been obtained for a quasioptical gyroklystron (QOGK) realized by the addition of an open-mirror prebunching resonator driven by an 85GHz, 1.5kW Extended Interaction Oscillator. Efficiency enhancement by mode priming has been investigated, and efficiencies up to 19% have been obtained by increasing the detuning of the operating mode. An overall efficiency of 30% was obtained by the addition of a simple depressed collector. The high circulating power in the QOG resonator is currently being considered for use as an electromagnetic wiggler for compact IR free-electron lasers. The QOG is also promising as a source for an active sensor of upper atmosphere trace impurities.

  12. New results and applications for the quasioptical gyrotron

    NASA Astrophysics Data System (ADS)

    Fliflet, Arne W.; Fischer, Richard P.; Manheimer, Wallace M.

    1993-07-01

    The quasi-optical gyrotron (QOG), which features an open resonator formed by a pair of spherical mirrors instead of the conventional gyrotron waveguide cavity, has been under development at the U.S. Naval Research Laboratory as a tunable high power millimeter-wave source for tokamak plasma heating, advanced radars, and power beaming. Results have recently been obtained for a quasi-optical gyroklystron (QOGK) realized by the addition of an open-mirror prebunching resonator driven by an 85 GHz, 1.5 kW extended interaction oscillator. Efficiency enhancement by mode priming has been investigated, and efficiencies up to 19 percent have been obtained by increasing the frequency detuning of the operating mode. An overall efficiency of 30 percent was obtained by the addition of a simple depressed collector. Phase-locked operation was demonstrated at a power of 57 kW and efficiency of 16 percent. The high circulating power in the QOG resonator is currently being considered for use as an electromagnetic wiggler for compact infrared FELs. The QOG is also promising as a source for an active sensor of upper atmosphere trace impurities.

  13. A simple quantum-electronic approach to the Gyrotron and its application to the solid-state gyrotron

    NASA Technical Reports Server (NTRS)

    Ho, P.-T.; Granatstein, V. L.

    1986-01-01

    A simple, unifying theory of the gyrotron is presented. It is of the Lamb type. Within its framework, important results from different approaches can be easily obtained. As an application, gyrotron action in InSb is reexamined, and coherent emission at 10 to the 12th Hz appears possible with an output power of about 0.5 mW/sq mm of the device.

  14. 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.

  15. 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.

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

    PubMed

    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

    2007-06-01

    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

  17. 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

  18. 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.

  19. The multi-mode gyrotron

    SciTech Connect

    Savilov, A. V.; Glyavin, M. Yu.; Philippov, V. N.

    2011-10-15

    It is possible to provide a situation in the gyrotron when it possesses a dense spectrum of axial eigenmodes having different frequencies but almost similar Q-factors. In this case, the single-frequency operation of the gyrotron is provided due to non-linear competition of the eigenmodes. It is shown that such an approach opens a way to provide in gyrotrons a close-to-continuous frequency tuning.

  20. 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.

  1. Optimization of operation of a three-electrode gyrotron with the use of a flow-type calorimeter

    SciTech Connect

    Kharchev, Nikolay K.; Batanov, German M.; Kolik, Leonid V.; Malakhov, Dmitrii V.; Petrov, Aleksandr Ye.; Sarksyan, Karen A.; Skvortsova, Nina N.; Stepakhin, Vladimir D.; Belousov, Vladimir I.; Malygin, Sergei A.; Tai, Yevgenii M.

    2013-01-15

    Results are presented for measurements of microwave power of the Borets-75/0.8 gyrotron with recovery of residual electron energy, which were performed by a flow-type calorimeter. This gyrotron is a part of the ECR plasma heating complex put into operation in 2010 at the L-2M stellarator. The new calorimeter is capable of measuring microwave power up to 0.5 MW. Monitoring of the microwave power makes it possible to control the parameters of the gyrotron power supply unit (its voltage and current) and the magnetic field of the cryomagnet in order to optimize the gyrotron operation and arrive at maximum efficiency.

  2. Optimization of operation of a three-electrode gyrotron with the use of a flow-type calorimeter.

    PubMed

    Kharchev, Nikolay K; Batanov, German M; Kolik, Leonid V; Malakhov, Dmitrii V; Petrov, Aleksandr Ye; Sarksyan, Karen A; Skvortsova, Nina N; Stepakhin, Vladimir D; Belousov, Vladimir I; Malygin, Sergei A; Tai, Yevgenii M

    2013-01-01

    Results are presented for measurements of microwave power of the Borets-75/0.8 gyrotron with recovery of residual electron energy, which were performed by a flow-type calorimeter. This gyrotron is a part of the ECR plasma heating complex put into operation in 2010 at the L-2M stellarator. The new calorimeter is capable of measuring microwave power up to 0.5 MW. Monitoring of the microwave power makes it possible to control the parameters of the gyrotron power supply unit (its voltage and current) and the magnetic field of the cryomagnet in order to optimize the gyrotron operation and arrive at maximum efficiency. PMID:23387650

  3. Slow processes in startup scenarios of long-pulse gyrotrons

    SciTech Connect

    Nusinovich, G. S.; Sinitsyn, O. V.; Antonsen, T. M. Jr.; Vlasov, A. N.; Cauffman, S. R.; Felch, K. L.

    2006-08-15

    A gyrotron startup scenario describes the variation of gyrotron parameters during onset of a pulse. This typically includes variations in beam parameters during the voltage rise, in the course of which the operating mode is excited and then driven to high efficiency operation while suppressing other parasitic modes. For long-pulse gyrotrons, however, additional processes with longer time constants should also be considered as part of the startup scenario. Such slow processes include ion neutralization of the beam space charge, thermal expansion of cavity walls caused by their ohmic heating, and reduction of the beam current due to emission cooling of the cathode. In the present paper, we analyze the importance of these effects on the stability and efficiency of gyrotron operation.

  4. 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.

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

    SciTech Connect

    Grimm, T.L.; Kreischer, K.E.; Temkin, R.J. )

    1993-11-01

    A detailed 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 electron cyclotron resonance heating (ECRH) of fusion plasmas. Two different radii beams produced by magnetron injection guns (MIG's) were used to excite the cylindrical waveguide cavity. The emission was found experimentally to be single mode, single frequency with a single rotation, which can be mode converted for transmission. The highest power reached with the larger radius electron beam was 1.2 MW at 230 GHz in the TE[sub 34,6] mode with an efficiency of 20% and beam parameters of 59 A and 100 kV. The highest power reached with the smaller radius electron beam 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 smaller radius beam gave a peak efficiency of 18% at 0.72 MW, 290 GHz in the TE[sub 25,14] mode. Efficiencies obtained in this experiment are about half that of less highly overmoded gyrotrons. Analysis of the experiment suggests that the low efficiency is primarily caused by azimuthal mode competition, in agreement with multimode theory for a tapered cavity. These experimental results show that megawatt power levels can be generated in continuous wave (cw) gyrotron oscillators at 200--300 GHz with efficiencies approaching 20%.

  6. Numerical studies of startup scenarios in a 1.5 MW, 110 GHz gyrotron operating in short pulses

    NASA Astrophysics Data System (ADS)

    Sinitsyn, Oleksandr; Nusinovich, Gregory; Antonsen, Thomas, Jr.; Tax, David; Temkin, Richard; Ireap, University Of Maryland Collaboration; Psfc, Massachusetts Institute Of Technology Collaboration

    2011-10-01

    Megawatt class gyrotrons operate in very high-order modes which form a very dense spectrum. In order to excite the operating mode in the presence of many competitors and drive it to the nominal operating point, careful control of the gyrotron's startup is necessary. Our studies are focused on the startup scenarios of the 110 GHz MIT gyrotron designed for operation at 1.5 MW power level in short pulses. Nominal parameters of the electron beam are: 96 kV, 42 A and orbital-to-axial velocity ratio α = 1.4. Previous numerical studies of the startup of this gyrotron had shown that at low voltages (at about 62 kV), first, the high-frequency TE23,6 mode was excited and then, at higher voltages (at about 74 kV), it was replaced by the desired TE22,6 mode. However, during a series of recent experiments at MIT it was shown that instead of the TE23,6 mode a low-frequency TE21,6 mode was excited during the voltage rise and persisted up to a voltage of 70 kV. In this work the authors make an attempt to simulate and explain this result with the help of self-consistent time-dependent code MAGY.

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

    PubMed

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

    2010-06-01

    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 TE(11,2) 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 TE(11,2,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

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

    PubMed

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

    2010-06-01

    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

  9. 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

  10. 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

  11. High pulse power rf sources for linear colliders

    SciTech Connect

    Wilson, P.B.

    1983-09-01

    RF sources with high peak power output and relatively short pulse lengths will be required for future high gradient e/sup +/e/sup -/ linear colliders. The required peak power and pulse length depend on the operating frequency, energy gradient and geometry of the collider linac structure. The frequency and gradient are in turn constrained by various parameters which depend on the beam-beam collision dynamics, and on the total ac wall-plug power that has been committed to the linac rf system. Various rf sources which might meet these requirements are reviewed. Existing source types (e.g., klystrons, gyrotrons) and sources which show future promise based on experimental prototypes are first considered. Finally, several proposals for high peak power rf sources based on unconventional concepts are discussed. These are an FEL source (two beam accelerator), rf energy storage cavities with switching, and a photocathode device which produces an rf current by direct emission modulation of the cathode.

  12. High-power corrugates waveguide components for mm-wave fusion heating systems

    SciTech Connect

    Olstad, R.A.; Doane, J.L.; Moeller, C.P.; O`Neill, R.C.; Di Martino, M.

    1996-10-01

    Considerable progress has been made over the last year in the U.S., Japan, Russia, and Europe in developing high power long pulse gyrotrons for fusion plasma heating and current drive. These advanced gyrotrons typically operate at a frequency in the range 82 GHz to 170 GHz at nearly megawatt power levels for pulse lengths up to 5 s. To take advantage of these new microwave sources for fusion research, new and improved transmission line components are needed to reliably transmit microwave power to plasmas with minimal losses. Over the last year, General Atomics and collaborating companies (Spinner GmbH in Europe and Toshiba Corporation in Japan) have developed a wide variety of new components which meet the demanding power, pulse length, frequency, and vacuum requirements for effective utilization of the new generation of gyrotrons. These components include low-loss straight corrugated waveguides, miter bends, miter bend polarizers, power monitors, waveguide bellows, de breaks, waveguide switches, dummy loads, and distributed windows. These components have been developed with several different waveguide diameters (32, 64, and 89 mm) and frequency ranges (82 GHz to 170 GHz). This paper describes the design requirements of selected components and their calculated and measured performance characteristics.

  13. 60kV, 10Amp DC power supply multiple input control and monitoring provision for the operation of various high power RF generation systems

    NASA Astrophysics Data System (ADS)

    Parmar, Kirit M.; Srinivas, Y. S. S.; Kulkarni, S. V.; ICRH-RF Group

    2010-02-01

    A 60 kV, 10 A DC power supply is used for testing of high power RF and microwave tubes e.g. Klystron, Gyrotron. Two 500 kW, 3.7 GHz klystrons, and one 82.6 GHz Gyrotron are located in SST1 Hall where as 200 kW; 28 GHz Gyrotron is located in Aditya Hall. The same power supply is required to operate, control and monitor various systems at different locations with easy change over from one system to other as per experimental requirements. An off line, control change over system, is designed to accomplish the above requirements, with control panels installed at desired different locations. The input (0 to 11 kV) A.C. voltage to power supply is given from a motorized voltage variation system (VVS). The control panels provide indication of A.C. input voltage to power supply from 11 kV potential transformers of VVS. In addition, the control panel is provided with 11 kV circuit breaker status indication and control i.e. Emergency OFF switch. The control panels are designed and developed indigenously which are successfully installed and are in continuous use for the safe and easy operation of different high power rf systems from the same DC power supply. The paper presents the design of the controls, monitoring and indications. Safety aspects of the system are also highlighted.

  14. Experimental Studies of sub-THz Gyrotron with Pulsed Solenoid for Air Breakdown Investigation

    NASA Astrophysics Data System (ADS)

    Kashyn, Dmytro; Nusinovich, Gregory; Rodgers, John; Romero-Talamás, Carlos; Shkvarunets, Anatoly

    2012-10-01

    The development of sub-THz gyrotron for air breakdown studies is one of the research tasks under the Center of Applied Electromagnetics program in University of Maryland. The goal is to remotely detect concealed radioactive materials as described by V. L. Granatstein and G. S. Nusinovich (J. Appl. Phys 108 063304 (2010)). There it was proposed to focus high-power sub-THz radiation in a small volume where the wave field exceeds the breakdown threshold. The presence of the radioactive material in the vicinity (<= 20-40m) of such volume significantly increases the probability of the air breakdown. The gyrotron can serve as a source of sub THz radiation required for this scheme. We report our experimental activities on the sub-THz gyrotron operating at 670 GHz at TE 31,8 mode with 28T pulsed magnetic field. This tube was developed in collaboration with Institute of Applied Physics of Russian Academy of Science. Our team was responsible for the design of major components while our colleagues manufactured the tube. We achieved 80 kW of output power in 10μs pulses which corresponds to 0.2 J of energy. We introduced several improvements to the original design addressing the issues with discharges and multipactoring that were impeding the performance of the tube. Unfortunately we had a catastrophic failure which ruined the existing device. We are now working on the design of another gyrotron that will operate at 220 GHz and can be capable of delivering 250-350 kW of RF power.

  15. 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.

  16. 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}.

  17. Development of THz-range Gyrotrons for Detection of Concealed Radioactive Materials

    NASA Astrophysics Data System (ADS)

    Nusinovich, Gregory S.; Pu, Ruifeng; Antonsen, Thomas M.; Sinitsyn, Oleksandr V.; Rodgers, John; Mohamed, Ali; Silverman, Joseph; Al-Sheikhly, Mohamad; Dimant, Yakov S.; Milikh, Gennady M.; Glyavin, Michael Yu.; Luchinin, Alexei G.; Kopelovich, Eugene A.; Granatstein, Victor L.

    2011-03-01

    The Center for Applied Electromagnetics (AppEl) at the University of Maryland had started development of a sub-THz gyrotron for detecting concealed radioactive materials. The concept is based on the use of a high-power gyrotron whose power being focused in a small spot with dimensions on the order of a wavelength exceeds the threshold level required for initiating a freely localized microwave breakdown in air. However, in the absence of radioactive materials, the ambient electron density is so small that there is a very small probability to find a free electron in this small volume to trigger the avalanche breakdown process. Therefore the fact that the breakdown was observed would indicate that there is a hidden radioactive material in the vicinity of a focused wave beam. We present the design data for a 200-300 kW, 670 GHz gyrotron operating with a pulsed solenoid and describe a single-shot pulsed solenoid producing 27-28 T magnetic fields. Also numerous issues in this specific application are discussed, viz. threshold conditions for initiating the breakdown, production of gamma rays by concealed radioactive materials and their role in producing low energy electrons outside a container, wave beam focusing in a small spot by a limited-size antenna, random walk of energetic electrons which may result in appearance of free electrons in a given volume during the RF pulse and comparison of diffusion time with the time required for competing processes, such as ionization and three-body attachment.

  18. 137-GHz gyrotron diagnostic for instability studies in Tara

    SciTech Connect

    Machuzak, J.S.; Woskoboinikow, P.; Mulligan, W.J.; Cohn, D.R.; Gerver, M.; Guss, W.; Mauel, M.; Post, R.S.; Temkin, R.J.

    1986-08-01

    A narrow linewidth (<100 kHz), 1-kW, 137-GHz gyrotron and an efficient TE/sub 03/ to TE/sub 11/ cylindrical waveguide mode converter set (>97% TE/sub 11/ mode output) have been built for collective Thomson scattering diagnostics. The main goal will be to study instability driven ion density fluctuations in the Tara plug such as the drift cyclotron loss cone (DCLC), the axial loss cone (ALC), harmonics of the DCLC and ALC, and the ion two-stream instability. The heterodyne receiver and signal optics have been installed on Tara. Background electron cyclotron emission (ECE) at 139 +- 1.5 GHz after electron cyclotron resonance heating (ECRH) in the Tara plug corresponded to equivalent blackbody temperatures of 453 and 70 eV for extraordinary and ordinary emission, respectively. The well-collimated receiver field of view completely through the Tara plug has allowed for excellent polarization discrimination of the ECE. The high-power capability of this gyrotron will allow weak fluctuation levels (n-italic-tilde/n-italic<10/sup -6/) to be detected above this background during ECRH in the plugs.

  19. Gyrotron transmitting tube

    NASA Technical Reports Server (NTRS)

    Kosmahl, H. G. (Inventor)

    1983-01-01

    An RF transmitting tube for the 20 GHz to 500 GHz range comprises a gyrotron and a multistage depressed collector. A winding provides a magnetic field which acts on spent, spinning or orbiting electrons changing their motion to substantially forward linear motion in a downstream direction. The spent electrons then pass through a focusser into the collector. Nearly all of the electrons injected into the collector will remain within an imaginary envelope as they travel forward toward the end collector plate. The apertures in the collector plates are at least as large in diameter as the envelope at any particular axial position.

  20. New developments and test of high power transmission components for ECRH on ASDEX-Upgrade and W7-AS

    SciTech Connect

    Empacher, L.; Foerster, W.; Gantenbein, G.; Kasparek, W.; Kumric, H.

    1995-12-31

    The installation of new 140 GHz systems for electron cyclotron heating on the tokamak ASDEX-Upgrade and the stellarator W7-AS with a power of 2 MW each and 3 s pulse length is underway. These systems use gyrotrons, developed by the Institute of Applied Physics, Nizhny Novgorod, and built by Toriy in Russia, as high power mm-wave sources. The gyrotrons can be operated for 3 s with 0.5 MW and for 1 s with 0.7 MW EHF output. The transmission of the millimetre wave power is realized by a combination of beam waveguides and corrugated HE{sub 11} waveguides. Components for transmission and high power diagnostics as well as first results are described together with the system.

  1. High-power microwave transmission and launching systems for fusion plasma heating systems

    SciTech Connect

    Bigelow, T.S.

    1989-01-01

    Microwave power in the 30- to 300-GHz frequency range is becoming widely used for heating of plasma in present-day fusion energy magnetic confinement experiments. Microwave power is effective in ionizing plasma and heating electrons through the electron cyclotron heating (ECH) process. Since the power is absorbed in regions of the magnetic field where resonance occurs and launching antennas with narrow beam widths are possible, power deposition location can be highly controlled. This is important for maximizing the power utilization efficiency and improving plasma parameters. Development of the gyrotron oscillator tube has advanced in recent years so that a 1-MW continuous-wave, 140-GHz power source will soon be available. Gyrotron output power is typically in a circular waveguide propagating a circular electric mode (such as TE/sub 0,2/) or a whispering-gallery mode (such as TE/sub 15,2/), depending on frequency and power level. An alternative high-power microwave source currently under development is the free-electron laser (FEL), which may be capable of generating 2-10 MW of average power at frequencies of up to 500 GHz. The FEL has a rectangular output waveguide carrying the TE/sub 0,1/ mode. Because of its higher complexity and cost, the high-average-power FEL is not yet as extensively developed as the gyrotron. In this paper, several types of operating ECH transmission systems are discussed, as well systems currently being developed. The trend in this area is toward higher power and frequency due to the improvements in plasma density and temperature possible. Every system requires a variety of components, such as mode converters, waveguide bends, launchers, and directional couplers. Some of these components are discussed here, along with ongoing work to improve their performance. 8 refs.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

    Lohr, John; Cengher, Mirela; Doane, John L.; Gorelov, Yuri A.; Moeller, Charles P.; Ponce, Dan; Prater, Ron

    2011-03-01

    The electron cyclotron heating and current drive complex on the DIII-D tokamak presently comprises six gyrotrons injecting rf power from the low field side at 110 GHz, the 2 f ce resonance at the center of the vacuum chamber. Typical injected rf power is 600-650 kW per gyrotron. The launched rf can be directed over ±20° toroidally to create both co- and counter-current drive and scanned over 40° poloidally to permit the injected rf beams to intersect, and be absorbed at, the second harmonic resonance anywhere in the tokamak upper half plane. The elliptical polarization is controlled so that the desired extraordinary or ordinary modes are excited for any injection geometry. The maximum injected energy on a single plasma shot has been 16.6 MJ for six gyrotrons injecting a total of 3.4 MW for 5 seconds.

  4. Research and development on high-power millimeter-wave and submillimeter-wave electron tubes

    NASA Astrophysics Data System (ADS)

    Mourier, G.

    Several high-power generators operating in the frequency range above 20 GHz are examined. These are hot-cathode vacuum tubes of the gyrotron type, which operate at voltages under 200 kV and in a magnetic field under 40 kG. A gyrotron research and development program is described, with particular emphasis on its computer-aided design and the use of superconducting magnets. Devices operating in frequency ranges above 200-300 GHz are described, and the concept of using transverse interaction rather than longitudinal interaction is discussed. Although transverse interaction has less energetic efficiency, its uniform magnetic field, high value of deceleration, and the possibility of using a wave with low group velocity make it a viable option. Devices incorporating a small electron accelerator in the same vacuum envelope and operating at relatively low voltage at higher frequencies are presently being investigated.

  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. Perspective gyrotron with mode converter for co- and counter-rotation operating modes

    NASA Astrophysics Data System (ADS)

    Chirkov, A. V.; Denisov, G. G.; Kuftin, A. N.

    2015-06-01

    A gyrotron oscillator operating efficiently at modes of both rotations was developed and tested. The gyrotron operation can be switched between two modes: co- and counter rotating ones with respect to electron rotation in a resonance magnetic field. A synthesized mode converter provides output of both waves in the form of two different paraxial wave beams corresponding to direction of the mode rotation. Measured gyrotron power (up to 2 MW), interaction efficiency (34%), and diffraction losses in the mode converter (≈2%) agree well with the design values. The proposed gyrotron scheme alloys principal enhancement in the device parameters—possibility of electronic switching of output wave beam direction and possibility to arrange an effective scheme to provide frequency/phase locking of a gyrotron-oscillator.

  7. Perspective gyrotron with mode converter for co- and counter-rotation operating modes

    SciTech Connect

    Chirkov, A. V.; Kuftin, A. N.; Denisov, G. G.

    2015-06-29

    A gyrotron oscillator operating efficiently at modes of both rotations was developed and tested. The gyrotron operation can be switched between two modes: co- and counter rotating ones with respect to electron rotation in a resonance magnetic field. A synthesized mode converter provides output of both waves in the form of two different paraxial wave beams corresponding to direction of the mode rotation. Measured gyrotron power (up to 2 MW), interaction efficiency (34%), and diffraction losses in the mode converter (≈2%) agree well with the design values. The proposed gyrotron scheme alloys principal enhancement in the device parameters—possibility of electronic switching of output wave beam direction and possibility to arrange an effective scheme to provide frequency/phase locking of a gyrotron-oscillator.

  8. 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.

  9. Progress on Gyrotrons for ITER and Future Fusion Reactors

    NASA Astrophysics Data System (ADS)

    Thumm, Manfred K.

    2009-11-01

    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-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 industrial

  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. Increase of Efficiency of Gyrotron by Optimizing Conditions of RF-field Emission

    SciTech Connect

    Kuklin, V. M.; Lapshin, V. I.; Puzyrkov, S. Yu

    2006-01-15

    Dependence of efficiency and output power on parameter which is equal to ratio of total emission power to accumulated energy is considered in simplified model of gyrotron. It is shown that this parameter changes with changing of emission conditions at the generator output, which leads to the change of field distribution inside of gyrotron as well. Behavior of efficiency and output power is introduced in the vicinity of their maximal values.

  12. Design of a Ka Band 35 kW CW Low-Voltage Harmonic Gyrotron

    NASA Astrophysics Data System (ADS)

    Geng, Zhi-Hui; Liu, Pu-Kun; Su, Yi Nong; Xu, Shou Xi; Xue, Qian Zhong

    2010-01-01

    In this paper, a continuous wave (CW) low-voltage second harmonic gyrotron with the conventional cavity has been preliminarily designed and evaluated with self-consistent nonlinear simulation code and the particle-in-cell code CHIPIC. The simulation results of the two codes are shown to be in agreement basically. The 35 kW CW output power of the designed harmonic gyrotron driven by a 25 kV 5.0A electron beam from a magnetron injection gun (MIG) is obtained. The maximum output power and the electronic efficiency of the gyrotron is about 35 kW and 30% respectively.

  13. 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)

  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. Upgraded Waveguide Components for New 1.2 and 1.5 MW Gyrotrons on the DIII-D Tokamak

    NASA Astrophysics Data System (ADS)

    Gorelov, Y. A.; Doane, J. L.; Cengher, M.; Lohr, J.; Ponce, D.

    2012-10-01

    The present gyrotron system on the DIII-D tokamak comprises 110 GHz gyrotrons in the 1 MW class with designed pulse lengths of 10 s. The system is being upgraded with two types of depressed collector gyrotrons producing 1.2 MW at 110 GHz and 1.5 MW at 117.5 GHz, for which waveguide components having higher power ratings will be required. New power monitors and polarizers have been designed and fabricated, which are capable of operating for 10 s pulses at the higher power levels. This presentation reports an analysis of the component heat loading to obtain a thermal equilibrium. Using this equilibrium, a stress strain analysis was performed to calculate life expectancies. The calculations take into account the temperature dependence of the heat transfer coefficient in the component coolant channels. Although the high heat load components required upgrading, the waveguide lines themselves have adequate margins for the expected power and pulse length. A summary of the thermal capabilities of other components will also be presented.

  16. Investigation of failure mechanisms in high-power microwave transmission windows

    NASA Astrophysics Data System (ADS)

    Bosman, Herman L.

    Thermal runaway and window failure restrict the power output of high power (˜1 MW), long pulse length (˜10 sec) gyrotrons used for plasma heating in magnetic confinement fusion experiments. Chemical vapor deposition diamond is used as window material due to its low loss tangent and high thermal conductivity, but still suffers from occasional, unpredictable failure. With the use of a simple model, it is shown that a uniform thin film of contaminant on a microwave window may absorb up to 50 percent of the incident power, even if the film thickness is only a small fraction of its resistive skin depth. The fraction of power absorbed by thin films on diamond gyrotron windows is estimated by comparison with published data obtained via two different experimental routes. Typically about a fraction of one percent of the incident power is absorbed by the thin films. Discontinuous surface films, where the surface contaminants have a patchy or island structure, are modeled with an equivalent transmission line circuit. Patchy surface contaminants on diamond gyrotron windows do not contribute significantly to the overall power absorbed on the window surface. An unexpected result is that most of the power is absorbed on the 'clean' window surface. The uniform thin film model is therefore adequate to describe surface power losses for diamond windows. The discontinuous film model, applied to alumina windows with TIN coatings, shows power absorption values of approximately 0.1--0.3%. Graphitic contaminants embedded in the CVD diamond absorb RE power from both the RE electric and magnetic field components. The absorbed power is insufficient to cause significant heating or cause graphitization in the diamond. The power absorbed in a diamond gyrotron window causes thermal gradient stresses in the window, with the maximum tensile stress occurring close to the window edge. For power absorption values up to 2000 W, the tensile stresses alone are insufficient to cause mechanical failure

  17. Phase-locking of a second-harmonic gyrotron oscillator using a quasi-optical circulator to separate injection and output signals

    SciTech Connect

    Guo, H.Z.; Rodgers, J.; Hoppe, D.J.

    1995-12-31

    Phase-locking in a 34.5 GHz special complex cavity gyrotron oscillator operating at the second harmonic of the electron cyclotron frequency was studied. Injection of the locking power was made via a quasi-optical circulator connected to the gyrotron output. Locking bandwidth was measured by comparing the phase of the injection signal and output signal using a balanced mixer. Locking was observed with input power level as low as 40 dB below the gyrotron output power. The locking bandwidth is, however, narrower than in gyrotrons operating at the fundamental cyclotron frequency which may be attributed to the longer resonant cavity in the second harmonic gyrotron and the corresponding larger value of external quality factor. The measurements are roughly in agreement with predictions of Adler`s phase-locking equation which is given for the system in terms of powers propagating in the output waveguide toward and away from the gyrotron cavity.

  18. Large-orbit gyrotron operation in the terahertz frequency range.

    PubMed

    Bratman, V L; Kalynov, Yu K; Manuilov, V N

    2009-06-19

    Coherent terahertz high-harmonic radiation has been obtained in a gyrotron with an axis-encircling electron beam. An electron-optical system with a cusp gun and a following drift section of adiabatic magnetic compression with an area factor of 3000 provides the formation of an 80-keV/0.7-A beam of gyrating electrons in a wide range of voltages and magnetic fields. Stable single-mode generation with a power of 0.3-1.8 kW in microsecond pulses is detected at four frequencies in the range 0.55-1.00 THz at resonant magnetic fields 10.5-14 T. PMID:19659020

  19. 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.

  20. Commissioning a Megawatt-class Gyrotron with Collector Potential Depression

    NASA Astrophysics Data System (ADS)

    Lohr, J.; Cengher, M.; Gorelov, Y. A.; Ponce, D.; Prater, R.

    2013-10-01

    A 110 GHz depressed collector gyrotron has been installed on the DIII-D tokamak. The commissioning process rapidly achieved operation at full parameters, 45 A and 94 kV total voltage, with 29 kV depression. Although short pulse, 2 ms, factory testing demonstrated 1.2 MW at 41% electrical efficiency, long pulse testing at DIII-D achieved only 33% efficiency at full power parameters, for pulse lengths up to 10 s. Maximum generated power was ~950 kW, considerably below the 1.2 MW target. During attempts to increase the power at 5 s pulse length, it was noted that the collector cooling water was boiling. This led to the discovery that 14 of the 160 cooling channels in the collector had been blocked by braze material during manufacture of the tube. The locations of blocked channels were identified using infrared imaging of the outside of the collector during rapid changes in the cooling water temperature. Despite these difficulties, the rf beam itself was of very high quality and the stray rf found calorimetrically in the Matching Optics Unit, which couples the Gaussian rf beam to the waveguide, was only 2% of the generated power, about half that of our previous best quality high power beam. Details of the power measurements and collector observations will be presented. Work supported by the US DOE under DE-FC02-04ER54698.

  1. 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).

  2. Use of High-Power Combiners and Fast Directional Switches in ECRH Systems

    SciTech Connect

    Bruschi, A.; Bin, W.; D'Arcangelo, O.; Muzzini, V.; Kasparek, W.; Plaum, B.; Erckmann, V.; Petelin, M.; Lubyako, L.

    2009-11-26

    The new generation of compact devices for the combination and the fast switching of high-power millimeter-wave beams [1] for Electron Cyclotron Heating (ECH) gives the possibility to switch the power (in tens of microseconds) between two lines (or two ECH launchers, even modulating it between them) and combine two gyrotron sources (or in principle even more) in one single transmission line, for doubling the transmitted power. This is useful in many respects in order to: 1){approx}double the efficiency in modulated EC for neoclassical Tearing Modes (NTM) stabilization, 2) avoid to switch-off gyrotrons in conventional (slow) switching, 3) electronically control the power sharing between different applications (heating/current-drive or NTM stabilization), 4) upgrade the existing ECH systems to twice the power without adding complete transmission lines and launchers, 5) test components at a power doubled with respect to the power capability of the available sources. This opens the way to the development of a more effective 'active' real-time control of the ECRH power routing and generally to more flexible and powerful ECH systems. The development of different devices and the advantages for (and in view of) ITER are addressed.

  3. 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.

  4. 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.

  5. Studying the start-up scenario for a pulsed gyrotron with a relativistic electron beam

    NASA Astrophysics Data System (ADS)

    Zaitsev, N. I.; Zapevalov, S. A.; Malygin, A. V.; Moiseev, M. A.; Shevchenko, A. S.

    2010-08-01

    We present the results of studying the start-up scenario for a high-power pulsed gyrotron operated at the TE53 mode for two variants of the current-voltage characteristic of a three-electrode magnetron-injection electron gun. In the standard variant of feeding the voltage to the first anode from the resistive divider, sequential generation of the TE73 and TE63 modes, and, finally, the operating TE53 mode was observed at the edge of the pulse. The current-voltage characteristic for which only the operating mode is excited is obtained by decreasing the growth rate of the voltage applied to the first anode.

  6. Gyrotron anode modulation of the Electron Cyclotron Resonant Heating (ECRH) from dc to 50 kHz on the Tandem Mirror Experiment-Upgrade (TMX-U)

    SciTech Connect

    Williams, C.W.; Heefner, J.W.; Rupert, R.R.

    1985-11-11

    This paper describes control of gyrotron microwave energy output by modulation of gyrotron anode voltage. At present, Electron Cyclotron Resonant Heating (ECRH) uses five gyrotrons on the Tandem Mirror Experiment-Upgrade (TMX-U) for plasma heating. One is in the 10 kG region of each end plug, one at the 5 kG region of each end plug, and one is used for central-cell heating. Also described are the design and operation of the anode modulation system. The operating advantages of gyrotron anode modulation include power balance, independent control of each gyrotron, an ability to modulate microwave output power up to 50 kHz, and gyrotron tuning. The performance results of anode modulation will be discussed. 9 figs.

  7. Free-Space Power Transmission

    NASA Technical Reports Server (NTRS)

    1989-01-01

    NASA Lewis Research Center organized a workshop on technology availability for free-space power transmission (beam power). This document contains a collection of viewgraph presentations that describes the effort by academia, industry, and the national laboratories in the area of high-frequency, high-power technology applicable to free-space power transmission systems. The areas covered were rectenna technology, high-frequency, high-power generation (gyrotrons, solar pumped lasers, and free electron lasers), and antenna technology.

  8. Gyrotron experiments employing a field emission array cathode

    SciTech Connect

    Garven, M.; Cooke, S.J.; Cross, A.W.; Phelps, A.D.R.; Spark, S.N.

    1995-12-31

    The design and operation of a field emission array (FEA) cathode for a millimeter wave gyrotron are presented. The FEA chip employed achieved 10mA reproducibly while operating in the environment of a gyrotron, namely in a vacuum of 1 {times} 10{sup {minus}8} mbar at voltages of up to 40kV. New methods are presented of mounting such FEA chips involving the shielding of the micron devices from voltages of up to 40kV, as experienced in a microwave device. The design parameters of the FEA gun were similar to those of a magnetron injection gun with cathode radius 12.5mm and slope angle 4{degree}. An electron beam current of up to 100mA was achievable from the FEA gyrotron cathode. An electrically isolated, fiber-optic, 10-channel control unit was developed to allow individual control of each chip. Electron beam powers of {approximately} 1kW were measured from the FEA cathode. To obtain oscillation, cavity inserts were employed in the electron beam-microwave interaction region to increase the cavity quality factor. Results are presented which verify the gyrotron interaction from the novel FEA cathode.

  9. 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.

  10. Gyrotron Frequency Stabilization by a Weak Reflected Wave

    NASA Astrophysics Data System (ADS)

    Glyavin, M. Yu.; Denisov, G. G.; Kulygin, M. L.; Mel'nikova, M. M.; Novozhilova, Yu. V.; Ryskin, N. M.

    2016-02-01

    The possibility of reducing the radiation frequency fluctuations by a factor of 3-5 using a nonresonant or highly resonant weakly reflecting load for the gyrotrons employed in controlled-fusion facilities is shown. The ranges of system parameters where the frequency stabilization is most effective were identified both analytically and numerically.

  11. 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.

  12. 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.

  13. 140-GHz gyrotron experiments based on a confocal cavity

    SciTech Connect

    Hu, W.; Shapiro, M.A.; Kreischer, K.E.; Temkin, R.J.

    1998-06-01

    The authors have designed and experimentally demonstrated the operation of a novel quasioptical gyrotron oscillator based on an overmoded confocal waveguide cavity. This cavity effectively suppresses undesired modes, and therefore has extremely low mode density. Stable single-mode, single-frequency operation was achieved in the TE06 mode at 136 GHz. A peak RF output power of 66 kW, corresponding to an efficiency of 18%, was measured. By varying the cavity magnetic field, high-power generation was observed at 136 GHz in the TE{sub 06} mode and at 114 GHz in the TE{sub 05} mode. These frequencies correspond to the high Q modes of the confocal resonator. The low Q modes were either weak or not observed. In this paper, the authors will review the design procedure for this cavity and present experimental data verifying its effectiveness in reducing the number of modes that can be excited. The confocal waveguide could also be used in high-power, gyro-TWT amplifiers to provide greater operating stability and bandwidth, especially in an overmoded waveguide structure.

  14. Development of Resonant Diplexers for high-power ECRH - Status, Applications, Plans

    NASA Astrophysics Data System (ADS)

    Kasparek, W.; Plaum, B.; Lechte, C.; Wu, Z.; Wang, H.; Maraschek, M.; Stober, J.; Wagner, D.; Reich, M.; Schubert, M.; Grünwald, G.; Monaco, F.; Müller, S.; Schütz, H.; Erckmann, V.; Doelman, N.; van den Braber, R.; Klop, W.; van den Brand, H.; Bongers, W.; Krijger, B.; Petelin, M.; Koposova, E.; Lubyako, L.; Bruschi, A.; Sakamoto, K.

    2015-03-01

    The development of diplexers for ECRH has been pursued at a number of institutes because of their attractive variety of applications: Power combination, non-mechanical, electrically controlled switching (of combined beams) between launchers with tens of kHz, and discrimination of low-power ECE signals from high-power ECRH is feasible. In a first part, this paper reports on plasma experiments with a ring resonator (Mk IIa) at ASDEX Upgrade. Commissioning experiments on fast switching between two launchers for synchronous stabilization of neoclassical tearing modes, as well as in-line ECE measurements have been performed, and experimental issues and first results are discussed. A clear influence of the switching phase on the amplitude of the 3/2 NTM mode was measured, complete stabilization could, however, not be demonstrated yet mainly due to imperfect resonator control. Concepts for improved tracking of the diplexers to the gyrotron frequency are presented. In a second part, the design of diplexers with ring resonators matched to HE11 fields is briefly discussed; these devices can be connected to corrugated waveguides without any mode converters. A compact version (MQ IV) is under investigation, which is compatible with the ITER ECRH system (170 GHz, 63.5 mm waveguide, vacuum tight casing), with the final goal of high-power tests at the 170 GHz gyrotron facility at JAEA in Naka, Japan. First low-power test results are presented.

  15. 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.

  16. 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.

  17. Development of High Power Vacuum Tubes for Accelerators and Plasma Heating

    NASA Astrophysics Data System (ADS)

    Srivastava, Vishnu

    2012-11-01

    High pulsed power magnetrons and klystrons for medical and industrial accelerators, and high CW power klystrons and gyrotrons for plasma heating in tokamak, are being developed at CEERI. S-band 2.0MW pulsed tunable magnetrons of centre frequency 2856MHz and 2998 MHz were developed, and S-band 2.6MW pulsed tunable magnetron is being developed for medical LINAC, and 3MW pulsed tunable magnetron is being developed for industrial accelerator. S-band (2856MHz), 5MW pulsed klystron was developed for particle accelerator, and S-band 6MW pulsed klystron is under development for 10MeV industrial accelerator. 350MHz, 100kW (CW) klystron is being developed for proton accelerator, and C-band 250kW (CW) klystron is being developed for plasma heating. 42GHz, 200kW (CW/Long pulse) gyrotron is under development for plasma heating. Plasma filled tubes are also being developed for switching. 25kV/1kA and 40kV/3kA thyratrons were developed for high voltage high current switching in pulse modulators for magnetrons and klystrons. 25kV/3kA Pseudospark switch of current rise time of 1kA/|a-sec and pulse repetition rate of 500Hz is being developed. Plasma assisted high power microwave device is also being investigated.

  18. Quasi-optical harmonic gyrotron and gyroklystron

    NASA Astrophysics Data System (ADS)

    Manheimer, W.; Levush, B.

    1985-12-01

    This patent discloses a method and apparatus for suppressing lower order cyclotron harmonics in order to permit resonance within a quasi-optical gyrotron/gyroklystron configuration of a desired high order harmonic. In the gyrotron/gyroklystron configuration at least one open resonator defined by at least two mirrors is positioned downstream from an electron beam source for receiving therethrough the beam of electrons and for exchanging energy therewith. This method includes the steps for choosing a mirror radius size large enough relative to the spot size of a desired radiation cyclotron harmonic so that the harmonic oscillates within the at least one resonator, but small enough so that the spot size for the next lower cyclotron harmonic is larger than the mirror so that harmonic does not oscillate due to diffraction losses. This method further includes the step of generating an electron beam bias the electron beam source with a beam current which is greater than or equal to the starting current for the desired nth cyclotron harmonic, but less than the starting current for the nth cyclotron harmonic.

  19. 28 GHz Gyrotron ECRH Upgrade for LDX

    NASA Astrophysics Data System (ADS)

    Michael, P. C.; Woskov, P. P.; Ellsworth, J. L.; Kesner, J.; Garnier, D. T.; Mauel, M. E.; Ellis, R. F.

    2009-11-01

    A 10 kW, CW, 28 GHz gyrotron is being implemented on LDX to increase the plasma density and to more fully explore the potential of high beta plasma stability in a dipole magnetic configuration. Higher density increases the heating of ions by thermal equilibration and allows for improved wave propagation in planned ICRF experiments. This represents over a 50% increase in the 17 kW ECRH from sources at 2.45, 6.4, and 10.5 GHz. The higher frequency will also make possible access to plasma densities of up to 10^13 cm-3. The 1 Tesla resonances are located above and below the floating coil near the dipole axial region. The gyrotron beam will be transmitted in TE01 mode in 32.5 mm diameter guide using one 90 bend and a short < 5 m straight waveguide run. A Vlasov launch antenna in LDX will direct the beam to the upper 1 Tesla resonance region. A layout of the planned system will be presented.

  20. High Power Hall Thrusters

    NASA Technical Reports Server (NTRS)

    Jankovsky, Robert; Tverdokhlebov, Sergery; Manzella, David

    1999-01-01

    The development of Hall thrusters with powers ranging from tens of kilowatts to in excess of one hundred kilowatts is considered based on renewed interest in high power. high thrust electric propulsion applications. An approach to develop such thrusters based on previous experience is discussed. It is shown that the previous experimental data taken with thrusters of 10 kW input power and less can be used. Potential mass savings due to the design of high power Hall thrusters are discussed. Both xenon and alternate thruster propellant are considered, as are technological issues that will challenge the design of high power Hall thrusters. Finally, the implications of such a development effort with regard to ground testing and spacecraft intecrati'on issues are discussed.

  1. Computer Aided Design of Depressed Collectors for High Power Electron Tubes

    NASA Astrophysics Data System (ADS)

    Singh, A.; Valfells, A.; Kolander, M.; Granatstein, V. L.

    2003-12-01

    We present an overview of techniques and computer codes developed by us for systematic design of depressed collectors with special reference to devices that use gyrating electron beams. These techniques facilitate achievement of high power levels in electron tubes. ProfilEM is an aid to controlling the trajectories of primary electrons. BSCAT provides for tracing the trajectories of backscattered electrons. Multiple generations of backscatter can be obtained, while keeping the number of rays to be tracked within manageable limits. We describe examples of applying these codes to the case of two-stage depressed collectors for a 1.5 MW 110 GHz gyrotron.

  2. CSTI High Capacity Power

    NASA Technical Reports Server (NTRS)

    Winter, Jerry M.

    1989-01-01

    The SP-100 program was established in 1983 by DOD, DOE, and NASA as a joint program to develop the technology necessary for space nuclear power systems for military and civil application. During FY-86 and 87, the NASA SP-100 Advanced Technology Program was devised to maintain the momentum of promising technology advancement efforts started during Phase 1 of SP-100 and to strengthen, in key areas, the chances for successful development and growth capability of space nuclear reactor power systems for future space applications. In FY-88, the Advanced Technology Program was incorporated into NASA's new Civil Space Technology Initiative (CSTI). The CSTI Program was established to provide the foundation for technology development in automation and robotics, information, propulsion, and power. The CSTI High Capacity Power Program builds on the technology efforts of the SP-100 program, incorporates the previous NASA SP-100 Advanced Technology project, and provides a bridge to NASA Project Pathfinder. The elements of CSTI High Capacity Power development include Conversion Systems, Thermal Management, Power Management, System Diagnostics, and Environmental Interactions. Technology advancement in all areas, including materials, is required to assure the high reliability and 7 to 10 year lifetime demanded for future space nuclear power systems. The overall program will develop and demonstrate the technology base required to provide a wide range of modular power systems as well as allowing mission independence from solar and orbital attitude requirements. Several recent advancements in CSTI High Capacity power development will be discussed.

  3. CSTI high capacity power

    SciTech Connect

    Winter, J.M.

    1994-09-01

    The SP-100 program was established in 1983 by DOD, DOE, and NASA as a joint program to develop the technology necessary for space nuclear power systems for military and civil application. During FY86 and 87, the NASA SP-100 Advanced Technology Program was devised to maintain the momentum of promising technology advancement efforts started during Phase I of SP-100 and to strengthen, in key areas, the chances for successful development and growth capability of space nuclear reactor power systems for future space applications. In FY88, the Advanced Technology Program was incorporated into NASA`s new Civil Space Technology Initiative (CSTI). The CSTI Program was established to provide the foundation for technology development in automation and robotics, information, propulsion, and power. The CSTI High Capacity Power Program builds on the technology efforts of the SP-100 program, incorporates the previous NASA SP-100 Advanced Technology project, and provides a bridge to NASA Project Pathfinder. The elements of CSTI High Capacity Power development include Conversion Systems, Thermal Management, Power Management, System Diagnostics, and Environmental Interactions. Technology advancement in all areas, including materials, is required to assure the high reliability and 7 to 10 year lifetime demanded for future space nuclear power systems. The overall program will develop and demonstrate the technology base required to provide a wide range of modular power systems as well as allowing mission independence from solar and orbital attitude requirements. Several recent advancements in CSTI High Capacity power development will be discussed.

  4. 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.

  5. Effective Cavity Length of Gyrotrons

    NASA Astrophysics Data System (ADS)

    Thumm, Manfred

    2014-12-01

    Megawatt-class gyrotron oscillators for electron cyclotron heating and non-inductive current drive (ECH&CD) in magnetically confined thermonuclear fusion plasmas have relatively low cavity quality factors in the range of 1000 to 2000. The effective length of their cavities cannot be simply deduced from the cavity electric field profile, since this has by far not a Gaussian shape. The present paper presents a novel method to estimate the effective length of a gyrotron cavity just from the eigenvalue of the operating TEm,n mode, the cavity radius and the exact oscillation frequency which may be numerically computed or precisely measured. This effective cavity length then can be taken to calculate the Fresnel parameter in order to confirm that the cavity is not too short so that the transverse structure of any mode in the cavity is the same as that of the corresponding mode in a long circular waveguide with the same diameter.

  6. 94 GHz, 25 kW CW, Harmonic Complex-Cavity Gyrotron

    NASA Astrophysics Data System (ADS)

    McDermott, D. B.; Balkcum Luhmann, A. J., Jr.

    1997-11-01

    A low-voltage second-harmonic gyrotron has been designed and evaluated with a particle-tracing code and the PIC code MAGIC. The two codes are shown to be in excellent agreement when applied to a conventional fundamental-frequency gyrotron and also to the novel second-harmonic gyrotron. The 25 kW CW, 94 GHz gyrotron with a predicted conversion efficiency of 28.5% and device efficiency of 20% is driven by a 25 kV, 5 A, v_t/v_z=1.5, MIG electron beam with 15% axial velocity spread and employs a TE_021/TE_031 complex cavity for mode control. The compact 17 kG solenoid magnet utilizes the tremendous advances made in high-Tc superconducting technology. However, the 94 GHz prototype will be tested at low duty in pulse mode with a conventional low-Tc superconducting magnet that has been received and tested.

  7. 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.

  8. Effect of background plasma on electromagnetic properties of coaxial gyrotron cavity

    NASA Astrophysics Data System (ADS)

    Moskvitina, Yu. K.; Zaginaylov, G. I.; Tkachenko, V. I.

    2014-07-01

    We analyze the effect of the background plasma on the electromagnetic properties of coaxial resonators with a smooth and a corrugated inner conductors used in high-power gyrotrons. It is shown that the plasma produces different effects on the modes with different signs of the azimuthal index, leading to a decrease or an increase in the resonance frequencies. A modification of the distributions of electromagnetic fields and the electromagnetic energy density by the background plasma occurs in such a way that Ohmic losses decrease both on the inner and on the outer conductors. In the case of a smooth inner conductor, this is due to a decrease in the field strengths on the surface of the conductors. If the inner conductor is corrugated, the background plasma leads to an increase in the field strengths on its surface. Nevertheless, the relative Ohmic loss power decreases due to an increase in the energy density in the resonator (which is also caused by the background plasma). Calculations were mainly performed for a coaxial resonator of a gyrotron operating on the TE34.19 mode (Karlsruhe, Germany).

  9. Initial high-power testing of the ATF (Advanced Toroidal Facility) ECH (electron cyclotron heating) system

    SciTech Connect

    White, T.L.; Bigelow, T.S.; Kimrey, H.D. Jr.

    1987-01-01

    The Advanced Toroidal Facility (ATF) is a moderate aspect ratio torsatron that will utilize 53.2 GHz 200 kW Electron Cyclotron Heating (ECH) to produce nearly current-free target plasmas suitable for subsequent heating by strong neutral beam injection. The initial configuration of the ECH system from the gyrotron to ATF consists of an optical arc detector, three bellows, a waveguide mode analyzer, two TiO/sub 2/ mode absorbers, two 90/sup 0/ miter bends, two waveguide pumpouts, an insulating break, a gate valve, and miscellaneous straight waveguide sections feeding a launcher radiating in the TE/sub 02/ mode. Later, a focusing Vlasov launcher will be added to beam the ECH power to the saddle point in ATF magnetic geometry for optimum power deposition. The ECH system has several unique features; namely, the entire ECH system is evacuated, the ECH system is broadband, forward power is monitored by a newly developed waveguide mode analyzer, phase correcting miter bends will be employed, and the ECH system will be capable of operating short pulse to cw. Initial high-power tests show that the overall system efficiency is 87%. The waveguide mode analyzer shows that the gyrotron mode output consists of 13% TE/sub 01/, 82.6% TE/sub 02/, 2.5% TE/sub 03/, and 1.9% TE/sub 04/. 4 refs.

  10. Time-domain self-consistent theory of frequency-locking regimes in gyrotrons with low-Q resonators

    SciTech Connect

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

    2015-03-15

    A time-domain theory of frequency-locking gyrotron oscillators with low-Q resonators has been developed. The presented theory is based on the description of wave propagation by a parabolic equation taking into account the external signal by modification of boundary conditions. We show that the developed model can be effectively used for simulations of both single- and multi-mode operation regimes in gyrotrons driven by an external signal. For the case of low-Q resonators typical for powerful gyrotrons, the external signal can influence the axial field profile inside the interaction space significantly and, correspondingly, the value of the electron orbital efficiency.

  11. 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. PMID:18232780

  12. Three-dimensional particle-in-cell modeling of terahertz gyrotrons with cylindrical and planar configurations of the interaction space

    SciTech Connect

    Zaslavsky, V. Yu.; Ginzburg, N. S.; Glyavin, M. Yu.; Zheleznov, I. V.; Zotova, I. V.

    2013-04-15

    We perform 3D particle-in-cell simulations of terahertz gyrotrons with two different configurations of the interaction space. For a gyrotron with conventional cylindrical configuration of the interaction cavity, we demonstrate reasonable agreement between simulations and experimental results, including output frequency, structure of the higher-order operating mode (TE{sub 17,4}), output power, and ohmic losses. For a novel planar gyrotron scheme with transverse energy extraction, a possibility of further increasing the oversized factor with the single-mode operation regime retained is shown. Frequency detuning by mechanical variation of the gap between waveguide plates is also demonstrated.

  13. Generation of 1.5-kW, 1-THz Coherent Radiation from a Gyrotron with a Pulsed Magnetic Field

    SciTech Connect

    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 {mu}sec 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.

  14. Time-domain self-consistent theory of frequency-locking regimes in gyrotrons with low-Q resonators

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    A time-domain theory of frequency-locking gyrotron oscillators with low-Q resonators has been developed. The presented theory is based on the description of wave propagation by a parabolic equation taking into account the external signal by modification of boundary conditions. We show that the developed model can be effectively used for simulations of both single- and multi-mode operation regimes in gyrotrons driven by an external signal. For the case of low-Q resonators typical for powerful gyrotrons, the external signal can influence the axial field profile inside the interaction space significantly and, correspondingly, the value of the electron orbital efficiency.

  15. High power millimeter wave experiment of ITER relevant electron cyclotron heating and current drive system.

    PubMed

    Takahashi, K; Kajiwara, K; Oda, Y; Kasugai, A; Kobayashi, N; Sakamoto, K; Doane, J; Olstad, R; Henderson, M

    2011-06-01

    High power, long pulse millimeter (mm) wave experiments of the RF test stand (RFTS) of Japan Atomic Energy Agency (JAEA) were performed. The system consists of a 1 MW/170 GHz gyrotron, a long and short distance transmission line (TL), and an equatorial launcher (EL) mock-up. The RFTS has an ITER-relevant configuration, i.e., consisted by a 1 MW-170 GHz gyrotron, a mm wave TL, and an EL mock-up. The TL is composed of a matching optics unit, evacuated circular corrugated waveguides, 6-miter bends, an in-line waveguide switch, and an isolation valve. The EL-mock-up is fabricated according to the current design of the ITER launcher. The Gaussian-like beam radiation with the steering capability of 20°-40° from the EL mock-up was also successfully proved. The high power, long pulse power transmission test was conducted with the metallic load replaced by the EL mock-up, and the transmission of 1 MW/800 s and 0.5 MW/1000 s was successfully demonstrated with no arcing and no damages. The transmission efficiency of the TL was 96%. The results prove the feasibility of the ITER electron cyclotron heating and current drive system. PMID:21721690

  16. High power millimeter wave experiment of ITER relevant electron cyclotron heating and current drive system

    SciTech Connect

    Takahashi, K.; Kajiwara, K.; Oda, Y.; Kasugai, A.; Kobayashi, N.; Sakamoto, K.; Doane, J.; Olstad, R.; Henderson, M.

    2011-06-15

    High power, long pulse millimeter (mm) wave experiments of the RF test stand (RFTS) of Japan Atomic Energy Agency (JAEA) were performed. The system consists of a 1 MW/170 GHz gyrotron, a long and short distance transmission line (TL), and an equatorial launcher (EL) mock-up. The RFTS has an ITER-relevant configuration, i.e., consisted by a 1 MW-170 GHz gyrotron, a mm wave TL, and an EL mock-up. The TL is composed of a matching optics unit, evacuated circular corrugated waveguides, 6-miter bends, an in-line waveguide switch, and an isolation valve. The EL-mock-up is fabricated according to the current design of the ITER launcher. The Gaussian-like beam radiation with the steering capability of 20 deg. - 40 deg. from the EL mock-up was also successfully proved. The high power, long pulse power transmission test was conducted with the metallic load replaced by the EL mock-up, and the transmission of 1 MW/800 s and 0.5 MW/1000 s was successfully demonstrated with no arcing and no damages. The transmission efficiency of the TL was 96%. The results prove the feasibility of the ITER electron cyclotron heating and current drive system.

  17. High power microwave generator

    DOEpatents

    Ekdahl, C.A.

    1983-12-29

    A microwave generator efficiently converts the energy of an intense relativistic electron beam (REB) into a high-power microwave emission using the Smith-Purcell effect which is related to Cerenkov radiation. Feedback for efficient beam bunching and high gain is obtained by placing a cylindrical Smith-Purcell transmission grating on the axis of a toroidal resonator. High efficiency results from the use of a thin cold annular highly-magnetized REB that is closely coupled to the resonant structure.

  18. High power microwave generator

    DOEpatents

    Ekdahl, Carl A.

    1986-01-01

    A microwave generator efficiently converts the energy of an intense relativistic electron beam (REB) into a high-power microwave emission using the Smith-Purcell effect which is related to Cerenkov radiation. Feedback for efficient beam bunching and high gain is obtained by placing a cylindrical Smith-Purcell transmission grating on the axis of a toroidal resonator. High efficiency results from the use of a thin cold annular highly-magnetized REB that is closely coupled to the resonant structure.

  19. The coaxial gyrotron with two electron beams. II. Dual frequency operation

    SciTech Connect

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

    2007-10-15

    The dual frequency operation (DFO) of the coaxial gyrotron with two electron beams (CGTB) has been investigated in this part by means of both linear theory and computer simulation. In such an operation, the cavity is at degeneration and one beam works at the first harmonic while another at high harmonic. Making use of the coupled-mode theory, the dispersion equation considering the coupling of two beams and two modes has been obtained. The results of the numerical calculation and the particle in cell simulation show that CGTB with DFO can obtain high output power at two different frequencies simultaneously. In addition, the power of the high harmonic can be enhanced due to the nonlinear coupling between two beams, and some interesting and important phenomena of CGTB with DFO revealed in the paper are of significance in physics.

  20. Precision characterization of gyrotron window materials. Final report, September 1, 1995--April 30, 1997

    SciTech Connect

    Dutta, J.M.; Jones, C.R.

    1998-03-03

    An optical resonator has been constructed to measure dielectric properties of materials at millimeter wavelengths. The objectives are the identification and loss measurements of window materials for high power gyrotrons. The source of radiation is from a backward wave oscillator (BWO) with enhanced power, good stability, and spectral purity. The measurement technique is based on the application of a high Q Fabry-Perot resonator which provides a means of determining the difference in the reciprocal Q-factors with high accuracy. Initial loss measurements at 150 GHz at room temperature are performed on sapphire. Preliminary loss tangent results on sapphire is found to be around 10{sup {minus}4} and are reported here. Work is in progress to develop a system which will scan the resonance rapidly to produce a measurement in less than a minute and to measure the loss as a function of temperature.

  1. Theory of High Power Electron Cyclotron Resonance Heating.

    NASA Astrophysics Data System (ADS)

    Taylor, Allan Watson

    1987-09-01

    Available from UMI in association with The British Library. Electron cyclotron resonance heating has been successfully used on a series of experiments in an attempt to raise plasma temperatures beyond the constraints of the resistive dissipation which occurs with ohmic heating. Recently progress in gyrotron design has allowed for significant increases in applied microwave power and for the first time a free electron laser will generate high power pulsed radio-frequency waves in the MTX experiment at Lawrence Livermore Laboratory in 1987. Classically the theory of ECRH has been considered by a Fokker-Planck approach and by a quasilinear approach. Both lead to a diffusion equation in velocity space for the distribution function but as the applied power increases the approximations made in these approaches are likely to become unsatisfactory. Adopting a test particle approach we firstly consider modifications to the velocity space diffusion co-efficient at high powers and then dispense with the diffusion equation completely. We begin by deriving averaged particle equations from a Lagrangian formulation which require less computer processor time to integrate than the exact Lorentz-force equations. These have been incorporated in a particle code to simulate ECRH in a tokamak. The results for this code are compared with analytic expressions derived for a modified diffusion coefficient and a probability function P(v,Deltav). We show that for low fields the diffusive form is correct but for higher fields nonlinear effects become important.

  2. A 250 GHz Photonic Band Gap Gyrotron Amplifier

    NASA Astrophysics Data System (ADS)

    Nanni, Emilio A.; Lewis, Samantha M.; Shapiro, Michael A.; Temkin, Richard J.

    2012-10-01

    Initial results for a high power 250 GHz gyrotron traveling wave tube (gyro-TWT) amplifier will be presented. The amplifier uses a novel photonic band gap (PBG) interaction circuit that confines the TE03-like mode for operation. Stability from oscillations in lower order modes is provided by the PBG circuit. At 26.6 kV and 0.25 A the gyro-TWT operates with peak small signal gain of 27.3 dB at 251 GHz. The instantaneous -3 dB bandwidth of the amplifier at peak gain is 0.4 GHz. The amplifier can be tuned for operation from 245-254 GHz. A peak output power of 7.5 W has been measured. Experimental results taken over a wide range of parameters, 15-30 kV and 0.25-0.5 A, show good agreement with a theoretical model in the small signal gain regime. The theoretical model incorporates cold test measurements for the transmission line, input coupler, PBG waveguide and mode converter.

  3. 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}.

  4. 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). PMID:26026544

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

    NASA Astrophysics Data System (ADS)

    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.

  6. High power density targets

    NASA Astrophysics Data System (ADS)

    Pellemoine, Frederique

    2013-12-01

    In the context of new generation rare isotope beam facilities based on high-power heavy-ion accelerators and in-flight separation of the reaction products, the design of the rare isotope production targets is a major challenge. In order to provide high-purity beams for science, high resolution is required in the rare isotope separation. This demands a small beam spot on the production target which, together with the short range of heavy ions in matter, leads to very high power densities inside the target material. This paper gives an overview of the challenges associated with this high power density, discusses radiation damage issues in targets exposed to heavy ion beams, and presents recent developments to meet some of these challenges through different projects: FAIR, RIBF and FRIB which is the most challenging. Extensive use of Finite Element Analysis (FEA) has been made at all facilities to specify critical target parameters and R&D work at FRIB successfully retired two major risks related to high-power density and heavy-ion induced radiation damage.

  7. 3.6MW Power Supply System of the 170GHz ECH&CD System in KSTAR

    NASA Astrophysics Data System (ADS)

    Shim, Eun-yong; Ahn, Il-kun; Seo, Tae-won; Lee, Seung-kyo; Bae, Young-soon; Joung, Jin-Hyun; Joung, Mi

    2012-09-01

    A 3.6 MW (-66 kV/55 A) Gyrotron power supply system was developed for the 170 GHz ECH&CD gyrotron system in KSTAR. This power supply system consists of Cathode Power Supply(CPS), Anode Power Supply(APS) and Body Power Supply(BPS). The CPS is using the Pulse Step Modulation by the 32set of IGBT choppers. The respons time of Chopper is very fast. So the cathode voltaget is able to be controlled rapidly. The APS is a sort of voltage devider using zener and switch component. It was achieved 3kHz modulation operation. The BPS is combined the commercial power supply and special high voltage switches. It is very simple topology but 5kHz modulation was accomplished easily. Theses power supply system were installed and commissioned successfully in 2011. This paper presents the topology of the each power supply and test result for 170 GHz gyrotron in KSTAR.

  8. High Power Cryogenic Targets

    SciTech Connect

    Gregory Smith

    2011-08-01

    The development of high power cryogenic targets for use in parity violating electron scattering has been a crucial ingredient in the success of those experiments. As we chase the precision frontier, the demands and requirements for these targets have grown accordingly. We discuss the state of the art, and describe recent developments and strategies in the design of the next generation of these targets.

  9. New high power coherent radiation sources. Memorandum report

    SciTech Connect

    Sprangle, P.; Coffey, T.

    1984-01-09

    In recent years, there has been considerable renewed interest in the development of novel devices for the production of high power coherent electromagnetic radiation. This interest has been motivated largely by the realization that, with existing technology, certain processes utilizing relativistic electron beams can produce coherent electromagnetic radiation at power levels far in excess of those achieved by conventional electron devices. This paper will review the current status of this rapidly developing field, with emphasis on two generic devices. The major thrust in the recent development of electron beam driven radiation sources has been directed towards achieving shorter wavelengths, greater power and higher efficiencies. Shortly after the development of such successful sources as the magnetron, kylstron and various traveling wave devices, it became clear that, in their original form, they were limited in their ability to produce high levels of radiation efficiently at short wavelengths. To circumvent the inherent limitations of these conventional coherent radiation sources, many new concepts and mechanisms, as well as variations on conventional concepts, were proposed. This paper is concerned primarily with two devices which are, relatively speaking, newcomers to the list of coherent classical radiation sources. They are the free electron laser and the cyclotron resonance maser (CRM); one well known type of CRM is the gyrotron.

  10. 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

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

    PubMed

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

    2005-06-01

    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 HE(11) -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

  12. High power connection system

    DOEpatents

    Schaefer, Christopher E.; Beer, Robert C.; McCall, Mark D.

    2000-01-01

    A high power connection system adapted for automotive environments which provides environmental and EMI shielding includes a female connector, a male connector, and a panel mount. The female connector includes a female connector base and a snap fitted female connector cover. The male connector includes a male connector base and a snap fitted male connector cover. The female connector base has at least one female power terminal cavity for seatably receiving a respective female power terminal. The male connector base has at least one male power terminal cavity for seatably receiving a respective male power terminal. The female connector is covered by a cover seal and a conductive shroud. A pair of lock arms protrude outward from the front end of the male connector base, pass through the panel mount and interface with a lever of a lever rotatably connected to the shroud to thereby mechanically assist mating of the male and female connectors. Safety terminals in the male and female connectors provide a last-to-connect-first-to-break connection with an HVIL circuit.

  13. 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.

  14. Application of Continuously Frequency-Tunable 0.4 THz Gyrotron to Dynamic Nuclear Polarization for 600 MHz Solid-State NMR

    NASA Astrophysics Data System (ADS)

    Matsuki, Yoh; Ueda, Keisuke; Idehara, Toshitaka; Ikeda, Ryosuke; Kosuga, Kosuke; Ogawa, Isamu; Nakamura, Shinji; Toda, Mitsuru; Anai, Takahiro; Fujiwara, Toshimichi

    2012-07-01

    In this paper we present results that demonstrate the utility of a continuously frequency-tunable 0.4 THz-gyrotron in a dynamic nuclear polarization (DNP)-enhanced solid-state NMR (SSNMR) spectroscopy at one of the highest magnetic fields, B 0 = 14.1 T (600 MHz for 1H Larmor frequency). Our gyrotron called FU CW VI generates sub-mm wave at a frequency near 0.4 THz with an output power of 4-25 W and a tunability over a range of more than 1 GHz by sweeping the magnetic field at the gyrotron cavity. We observed overall down shifting of the central frequency by up to ~1 GHz at high radiation duty factors and beam current, presumably due to the cavity thermal expansion by a heating, but the tunable range was not significantly changed. The frequency tunability facilitated the optimization of the DNP resonance condition without time-consuming field-sweep of the high-resolution NMR magnet, and enabled us to observe substantial enhancement of the SSNMR signal ( ɛ DNP = 12 at 90 K).

  15. 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.

  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. 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.

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

    NASA Astrophysics Data System (ADS)

    Avramidis, K. A.

    2015-12-01

    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.

  19. 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.

  20. Chaotic electron dynamics in gyrotron resonators

    SciTech Connect

    Kominis, Y.; Dumbrajs, O.; Avramides, K.A.; Hizanidis, K.; Vomvoridis, J.L.

    2005-04-15

    Phase space analysis of electron dynamics is used in combination with the canonical perturbation method and the KAM (Kolmogorov-Arnold-Moser) theory in order to study the dependence of the efficient gyrotron operation on the rf field profile and frequency mismatch. Knowledge of the boundaries of the electron motion provided through robust (slightly distorted) KAM surfaces is useful for optimizing depressed collectors and thereby for enhancement of overall efficiency of gyrotron operation.

  1. Resonant Cavities for Frequency Tunable Gyrotrons

    NASA Astrophysics Data System (ADS)

    Sabchevski, S.; Idehara, T.

    2008-01-01

    In this paper we present, discuss and compare several concepts based on both well-known and novel ideas for tunable gyrotron cavities. Although theoretical and design considerations are presented and discussed together the main focus is on the underlying principles and feasibility of different approaches rather than on their specific implementations. Illustrative examples are provided for configurations and frequency range appropriate for gyrotrons used as radiation sources for NMR spectroscopy with signal enhancement through DNP.

  2. High power arcjet

    NASA Technical Reports Server (NTRS)

    Goelz, T. M.; Auweter-Kurtz, M.; Kurtz, H. L.; Schrade, H. O.

    1992-01-01

    In this period a new mass flow controller was brought into the gas supply system, so that the upper limit for the mass flow rate could be increased up to 500 mg/s with hydrogen. A maximum specific impulse of 1500 s could be achieved with the high powered arcjet (HIPARC) at an efficiency of slightly better than 20 percent. Different nozzle throat diameters had been tested. The 100 kilo-watt input power limit was reached with the 4 mm nozzle throat diameter at a mass flow rate of 400 mg/s. Tests were carried out with different cathode gaps and with three different cathodes. In addition measurements of pressure and gas temperature were taken in the feed line in order to determine the pressure drop in the propellant injectors.

  3. Fast switching, modular high-voltage DC/AC-power supplies for RF-Amplifiers and other applications

    SciTech Connect

    Alex, J.; Schminke, W.

    1995-12-31

    A new kind of high voltage high-power Pulse-Step Modulator (PSM) for broadcast transmitters, accelerator sources, for NBI (Neutral Beam Injection for Plasma Heating), gyrotrons and klystrons has been developed. Since its first introduction in 1984 for broadcast transmitters, more than 100 high-power sound broadcast transmitters had been equipped with the first generation of the PSM modulators, using Gate Turn-Off Thyristors (GTOs) as switching elements. Recently, due to faster switching elements and making use of the latest DSP technologies (Digital Signal Processing), the performance data and areas of application could be extended further. In 1994, a precision high voltage source for MW gyrotrons was installed at CRPP in Lausanne. Supplementary very low cost solutions for lower powers but high voltages had been developed. Hence, today, a large area of applications can be satisfied with the family of solutions. The paper describes the principle of operation, the related control systems and refers to some particular applications of the PSM amplifiers, especially the newest developments and corresponding field results.

  4. 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

  5. 250GHz CW gyrotron oscillator for dynamic nuclear polarization in biological solid state NMR.

    PubMed

    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 9T, corresponding to 380 MHz (1)H 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-(13)C, (15)N]-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

  6. 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

  7. HIGH POWER PULSED OSCILLATOR

    DOEpatents

    Singer, S.; Neher, L.K.

    1957-09-24

    A high powered, radio frequency pulse oscillator is described for generating trains of oscillations at the instant an input direct voltage is impressed, or immediately upon application of a light pulse. In one embodiment, the pulse oscillator comprises a photo-multiplier tube with the cathode connected to the first dynode by means of a resistor, and adjacent dynodes are connected to each other through adjustable resistors. The ohmage of the resistors progressively increases from a very low value for resistors adjacent the cathode to a high value adjacent the plate, the last dynode. Oscillation occurs with this circuit when a high negative voltage pulse is applied to the cathode and the photo cathode is bombarded. Another embodiment adds capacitors at the resistor connection points of the above circuit to increase the duration of the oscillator train.

  8. High voltage power supply

    NASA Technical Reports Server (NTRS)

    Ruitberg, A. P.; Young, K. M. (Inventor)

    1985-01-01

    A high voltage power supply is formed by three discrete circuits energized by a battery to provide a plurality of concurrent output signals floating at a high output voltage on the order of several tens of kilovolts. In the first two circuits, the regulator stages are pulse width modulated and include adjustable ressistances for varying the duty cycles of pulse trains provided to corresponding oscillator stages while the third regulator stage includes an adjustable resistance for varying the amplitude of a steady signal provided to a third oscillator stage. In the first circuit, the oscillator, formed by a constant current drive network and a tuned resonant network included a step up transformer, is coupled to a second step up transformer which, in turn, supplies an amplified sinusoidal signal to a parallel pair of complementary poled rectifying, voltage multiplier stages to generate the high output voltage.

  9. 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

  10. 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.

  11. 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)

  12. 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. PMID:23539422

  13. 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.

  14. High Power Density Motors

    NASA Technical Reports Server (NTRS)

    Kascak, Daniel J.

    2004-01-01

    With the growing concerns of global warming, the need for pollution-free vehicles is ever increasing. Pollution-free flight is one of NASA's goals for the 21" Century. , One method of approaching that goal is hydrogen-fueled aircraft that use fuel cells or turbo- generators to develop electric power that can drive electric motors that turn the aircraft's propulsive fans or propellers. Hydrogen fuel would likely be carried as a liquid, stored in tanks at its boiling point of 20.5 K (-422.5 F). Conventional electric motors, however, are far too heavy (for a given horsepower) to use on aircraft. Fortunately the liquid hydrogen fuel can provide essentially free refrigeration that can be used to cool the windings of motors before the hydrogen is used for fuel. Either High Temperature Superconductors (HTS) or high purity metals such as copper or aluminum may be used in the motor windings. Superconductors have essentially zero electrical resistance to steady current. The electrical resistance of high purity aluminum or copper near liquid hydrogen temperature can be l/lOO* or less of the room temperature resistance. These conductors could provide higher motor efficiency than normal room-temperature motors achieve. But much more importantly, these conductors can carry ten to a hundred times more current than copper conductors do in normal motors operating at room temperature. This is a consequence of the low electrical resistance and of good heat transfer coefficients in boiling LH2. Thus the conductors can produce higher magnetic field strengths and consequently higher motor torque and power. Designs, analysis and actual cryogenic motor tests show that such cryogenic motors could produce three or more times as much power per unit weight as turbine engines can, whereas conventional motors produce only 1/5 as much power per weight as turbine engines. This summer work has been done with Litz wire to maximize the current density. The current is limited by the amount of heat it

  15. High power microwave generator

    SciTech Connect

    Minich, Roger W.

    1988-01-01

    A device (10) for producing high-powered and coherent microwaves is described. The device comprises an evacuated, cylindrical, and hollow real cathode (20) that is driven to inwardly field emit relativistic electrons. The electrons pass through an internally disposed cylindrical and substantially electron-transparent cylindrical anode (24), proceed toward a cylindrical electron collector electrode (26), and form a cylindrical virtual cathode (32). Microwaves are produced by spatial and temporal oscillations of the cylindrical virtual cathode (32), and by electrons that reflex back and forth between the cylindrical virtual cathode (32) and the cylindrical real cathode (20).

  16. High power coaxial ubitron

    NASA Astrophysics Data System (ADS)

    Balkcum, Adam J.

    In the ubitron, also known as the free electron laser, high power coherent radiation is generated from the interaction of an undulating electron beam with an electromagnetic signal and a static periodic magnetic wiggler field. These devices have experimentally produced high power spanning the microwave to x-ray regimes. Potential applications range from microwave radar to the study of solid state material properties. In this dissertation, the efficient production of high power microwaves (HPM) is investigated for a ubitron employing a coaxial circuit and wiggler. Designs for the particular applications of an advanced high gradient linear accelerator driver and a directed energy source are presented. The coaxial ubitron is inherently suited for the production of HPM. It utilizes an annular electron beam to drive the low loss, RF breakdown resistant TE01 mode of a large coaxial circuit. The device's large cross-sectional area greatly reduces RF wall heat loading and the current density loading at the cathode required to produce the moderate energy (500 keV) but high current (1-10 kA) annular electron beam. Focusing and wiggling of the beam is achieved using coaxial annular periodic permanent magnet (PPM) stacks without a solenoidal guide magnetic field. This wiggler configuration is compact, efficient and can propagate the multi-kiloampere electron beams required for many HPM applications. The coaxial PPM ubitron in a traveling wave amplifier, cavity oscillator and klystron configuration is investigated using linear theory and simulation codes. A condition for the dc electron beam stability in the coaxial wiggler is derived and verified using the 2-1/2 dimensional particle-in-cell code, MAGIC. New linear theories for the cavity start-oscillation current and gain in a klystron are derived. A self-consistent nonlinear theory for the ubitron-TWT and a new nonlinear theory for the ubitron oscillator are presented. These form the basis for simulation codes which, along

  17. Electron Optical System of the Sub-terahertz Coaxial Gyrotron with Continuous Frequency Tuning

    NASA Astrophysics Data System (ADS)

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

    2010-08-01

    Analytical estimations and the results of numerical analysis of the electron beam parameters in the reverse moderate power (15 kV/1A) Magnetron Injection Gun (MIG) for a coaxial 394.6 GHz gyrotron are presented. The design of the MIG with a movable inner rod is discussed, and the influence of emitter roughness is analyzed.

  18. W-band TE{sub 01} gyrotron backward-wave oscillator with distributed loss

    SciTech Connect

    Chang, T. H.; Yu, C. F.; Hung, C. L.; Yeh, Y. S.; Hsiao, M. C.; Shin, Y. Y.

    2008-07-15

    Distributed wall loss is proposed to enhance the stability and tunability of a W-band TE{sub 01} gyrotron backward-wave oscillator (gyro-BWO). Simulation results reveal that loss effectively suppresses the unwanted transverse modes as well as the high-order axial modes (HOAMs) without degrading the performance of a gyro-BWO that operates at the fundamental axial mode. Linear and nonlinear codes are used to calculate the interaction properties. The effects of the distributed loss on the starting currents of all of the modes of interest are discussed in depth. The interacting structure is optimized for stability. The calculated peak output power is 102 kW, corresponding to an efficiency of 20%. The 3 dB tuning bandwidth is 1.8 GHz, centered at 94.0 GHz when using 5 A and 100 kV electron beam.

  19. Nonlinearly driven oscillations in the gyrotron traveling-wave amplifier

    SciTech Connect

    Chiu, C. C.; Pao, K. F.; Yan, Y. C.; Chu, K. R.; Barnett, L. R.; Luhmann, N. C. Jr.

    2008-12-15

    By delivering unprecedented power and gain, the gyrotron traveling-wave amplifier (gyro-TWT) offers great promise for advanced millimeter wave radars. However, the underlying physics of this complex nonlinear system is yet to be fully elucidated. Here, we report a new phenomenon in the form of nonlinearly driven oscillations. A zero-drive stable gyro-TWT is shown to be susceptible to a considerably reduced dynamic range at the band edge, followed by a sudden transition into driven oscillations and then a hysteresis effect. An analysis of this unexpected behavior and its physical interpretation are presented.

  20. The 110 GHz Gyrotron System on DIII-D: Gyrotron Tests and Physics Results

    SciTech Connect

    J. Lohr; P. Calahan; R.W. Callis; T.S. Chu; J.S. deGrassie; I. Gorelov; H. Ikezi; R.A. Legg; T.C. Luce; C.C. Petty; D. Ponce; R. Prater; D.J. Schuster; S.E. Tsimring

    1999-12-01

    The DIII-D tokamak has installed a system with three gyrotrons at the 1 MW level operating at 110 GHz. Physics experiments on electron cyclotron current drive, heating, and transport have been performed. Good efficiency has been achieved both for on-axis and off-axis current drive with relevance for control of the current density profile leading to advanced regimes of tokamak operation, although there is a difference between off-axis ECCD efficiency inside and outside the magnetic axis. Heating efficiency is excellent and electron temperatures up to 10 keV have been achieved. The gyrotron system is versatile, with poloidal scan and control of the polarization of the injected rf beam. Phase correcting mirrors form a Gaussian beam and focus it into the waveguide. Both perpendicular and oblique launch into the tokamak have been used. Three different gyrotron designs are installed and therefore unique problems specific to each have been encountered, including parasitic oscillations, mode hops during modulation and polarization control problems. Two of the gyrotrons suffered damage during operations, one due to filament failure and one due to a vacuum leak. The repairs and subsequent testing will be described. The transmission system uses evacuated, windowless waveguide and the three gyrotrons have output windows of three different materials. One gyrotron uses a diamond window and generates a Gaussian beam directly. The development of the system and specific tests and results from each of the gyrotrons will be presented. The DIII-D project has committed to an upgrade of the system, which will add three gyrotrons in the 1 MW class, all using diamond output windows, to permit operation at up to ten seconds per pulse at one megawatt output for each gyrotron.

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

    PubMed

    Griffin, Robert G

    2011-12-01

    In the 1990's we initiated development of high frequency gyrotron microwave sources with the goal of performing dynamic nuclear polarization at magnetic fields (∼5-23 T) used in contemporary NMR experiments. This article describes the motivation for these efforts and the developments that led to the operation of a gyrotron source for DNP operating at 250 GHz. We also mention results obtained with this instrument that would have been otherwise impossible absent the increased sensitivity. Finally, we describe recent efforts that have extended DNP to 460 GHz and 700 MHz (1)H frequencies. PMID:22152359

  2. Dynamic nuclear polarization at 9T using a novel 250 Gyrotron microwave source

    NASA Astrophysics Data System (ADS)

    Griffin, Robert G.

    2011-12-01

    In the 1990's we initiated development of high frequency gyrotron microwave sources with the goal of performing dynamic nuclear polarization at magnetic fields (˜5-23 T) used in contemporary NMR experiments. This article describes the motivation for these efforts and the developments that led to the operation of a gyrotron source for DNP operating at 250 GHz. We also mention results obtained with this instrument that would have been otherwise impossible absent the increased sensitivity. Finally, we describe recent efforts that have extended DNP to 460 GHz and 700 MHz 1H frequencies.

  3. Linear theory of frequency pulling in gyrotrons

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    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.

  4. Experimental observation of the effect of aftercavity interaction in a depressed collector gyrotron oscillator

    SciTech Connect

    Choi, E. M.; Shapiro, M. A.; Sirigiri, J. R.; Temkin, R. J.

    2007-09-15

    This paper presents the experimental observation of the effect of an aftercavity interaction (ACI) in a depressed collector gyrotron oscillator. The gyrotron generates an output power of 1.5 MW at 110 GHz in 3 {mu}s pulses with a 96 kV and 40 A electron beam and has a single-stage depressed collector. The ACI arises from an unintended cyclotron resonant interaction between the microwave beam traveling out from the cavity and the gyrating electron beam. The interaction occurs in the uptaper of the launcher, immediately downstream from the cavity, where the magnetic field is slightly lower than its value in the cavity region. The ACI results in a reduction in efficiency since the electron beam tends to extract power from the wave. There is also a broadening of the spent beam energy profile, which reduces the effectiveness of the depressed collector and in turn limits the overall efficiency of a gyrotron. Measurements of the maximum depression voltage of the collector vs beam current at 96 kV are compared with simulations from the MAGY code [M. Botton et al., IEEE Trans. Plasma Sci. 26, 882 (1998)]. Excellent agreement is obtained between theory and experiment but only if the ACI is included. In the present experiment, it is estimated that the observed efficiency of 50% would have been about 60% in the absence of the ACI. These results verify the role of the ACI in reducing the efficiency of the gyrotron interaction.

  5. 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.

  6. High-Efficiency Power Module

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N. (Inventor); Wintucky, Edwin G. (Inventor)

    2015-01-01

    One or more embodiments of the present invention pertain to an all solid-state microwave power module. The module includes a plurality of solid-state amplifiers configured to amplify a signal using a low power stage, a medium power stage, and a high power stage. The module also includes a power conditioner configured to activate a voltage sequencer (e.g., bias controller) when power is received from a power source. The voltage sequencer is configured to sequentially apply voltage to a gate of each amplifier and sequentially apply voltage to a drain of each amplifier.

  7. High-Efficiency Power Module

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N (Inventor); Wintucky, Edwin G (Inventor)

    2013-01-01

    One or more embodiments of the present invention pertain to an all solid-state microwave power module. The module includes a plurality of solid-state amplifiers configured to amplify a signal using a low power stage, a medium power stage, and a high power stage. The module also includes a power conditioner configured to activate a voltage sequencer (e.g., bias controller) when power is received from a power source. The voltage sequencer is configured to sequentially apply voltage to a gate of each amplifier and sequentially apply voltage to a drain of each amplifier.

  8. 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)

  9. 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.

  10. 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.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

    2011-05-01

    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. High power ultrasound standard.

    PubMed

    Wong, George S K; Wu, Lixue

    2002-04-01

    A sensitive radiation force balance for laboratory measurement of ultrasonic power is presented. The principle of the system is based on measuring the ultrasonic radiation force exerted on a conical float suspended in water. Technical details of the implementation of the economically attractive system are described. The operation of the system is automated with the aid of the IEEE-488 bus and a desktop computer. Design aspects that affect measurement uncertainty are investigated. A theoretical model for the measurement of ultrasonic power with a conical reflector target is discussed. The expanded uncertainty (95% confidence level) of the above radiation force conical float system is estimated to be between 5% to 10%. PMID:12002863

  14. APPLICATIONS OF NEW TECHNOLOGY FOR PRODUCTION OF HIGH POWER MILLIMETER WAVES TO MAGNETIC FUSION RESEARCH

    SciTech Connect

    J. LOHR

    2002-08-01

    Although research on magnetically confined fusion plasmas has been carried out for a half century, for most of this time control of the temperature, density and current density profiles has been limited and transient. Now, high power long pulse gyrotron systems with excellent reliability are coming on line, which can provide non-inductively driven currents and electron heating leading to higher plasma performance and continuous operation in reactor relevant regimes. The precision of the location at which heating and current drive are applied has also made it possible to suppress certain classes of plasma instabilities. Basic physics of electron cyclotron current drive and heating are understood and these new technological capabilities are being exploited in magnetic confinement devices worldwide.

  15. Gyrotron Performance on the 110 GHZ Installation at the DIII-D Tokamak

    SciTech Connect

    Gorelov, I.; Lohr, J.M.; Ponce, D.; Callis, R.W.; Ikezi, H.; Legg, R.A.; Tsimring, S.E.

    1999-06-01

    The 110 GHz gyrotron system on the DIII-D tokamak comprises three different gyrotrons in the 1 MW class. The individual gyrotron characteristics and the operational experience with the system are described.

  16. Frequency-Based Investigation of Charge Neutralization Processes and Thermal Cavity Expansion in Gyrotrons

    NASA Astrophysics Data System (ADS)

    Schlaich, Andreas; Wu, Chuanren; Pagonakis, Ioannis; Avramidis, Konstantinos; Illy, Stefan; Gantenbein, Gerd; Jelonnek, John; Thumm, Manfred

    2015-09-01

    During the first hundred milliseconds, the frequency and RF output power of long pulse operating gyrotrons undergo deterministic variation. This well-known behavior is caused by the thermal expansion of the cavity and internal electrostatic processes related to the ionization of residual gas. A macroscopic analytical investigation of the gas conditions in modern gyrotrons indicates that ionization processes are unlikely to influence the overall internal gas pressure. In combination with electrostatic potential considerations, it was found that the beam depression voltage is not fully neutralized; in the case of W7-X gyrotrons, a maximum value of about 60 % neutralization is expected, in conflict with the common assumption of full neutralization in steady state. Using experimentally measured frequency shifts and the Evridiki gyrotron interaction simulation code, a fitting process was employed to further investigate these effects. The results are in very good agreement with the theoretical predictions and allow a separation of the time constants of the two processes causing the frequency tuning.

  17. High power phase shifter

    SciTech Connect

    Foster, B.; Gonin, I.; Khabiboulline, T.; Makarov, A.; Solyak, N.; Terechkine, I.; Wildman, D.; /Fermilab

    2005-05-01

    One of the approaches to power distribution system of a superconducting proton linac under discussion at FNAL requires development of a fast-action, megawatt-range phase shifter. Using a couple of this kind of devices with a waveguide hybrid junction can allow independent control of phase and amplitude of RF power at the input of each superconducting cavity, which will result in significant saving in number of klystrons and modulators required for the accelerator. A prototype of a waveguide version of the shifter that uses Yttrium-Iron Garnet (YIG) blocks was developed and tested. This report presents design concept of the device, and main results of simulation and proof-of-principle tests.

  18. Mode suppression means for gyrotron cavities

    DOEpatents

    Chodorow, Marvin; Symons, Robert S.

    1983-08-09

    In a gyrotron electron tube of the gyro-klystron or gyro-monotron type, having a cavity supporting an electromagnetic mode with circular electric field, spurious resonances can occur in modes having noncircular electric field. These spurious resonances are damped and their frequencies shifted by a circular groove in the cavity parallel to the electric field.

  19. 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.

  20. High Power Pulsed Gas Lasers

    NASA Astrophysics Data System (ADS)

    Witteman, W. J.

    1987-09-01

    Gas lasers have shown to be capable of delivering tens of terrawatt aspeak power or tens of kilowatt as average power. The efficiencies of most high power gas lasers are relatively high compared with other types of lasers. For instance molecular lasers, oscillating on low lying vibrational levels, and excimer lasers may have intrinsic efficiencies above 10%.The wavelengths of these gas lasers cover the range from the far infrared to the ultra-violet region, say from 12000 to 193 nm. The most important properties are the scalability, optical homogeneity of the excited medium, and the relatively low price per watt of output power. The disadvantages may be the large size of the systems and the relatively narrow line width with limited tunability compared with solid state systems producing the same peak power. High power gas lasers group into three main categories depending on the waste-heat handling capacity.

  1. Numerical simulations of a co-harmonic gyrotron

    NASA Astrophysics Data System (ADS)

    Constable, D. A.; Ronald, K.; He, W.; Phelps, A. D. R.; Cross, A. W.; Savilov, A. V.; Bratman, V. L.; Bandurkin, I. V.

    2012-02-01

    A co-harmonic gyrotron, operating simultaneously at the second and fourth harmonics of the electron cyclotron frequency, has been successfully modelled with the particle-in-cell code, Magic 3D. Results show excitation of the TE2,2 and TE4,3 waveguide modes, at frequencies of 37.5 GHz and 75 GHz, respectively, consistent with experimental measurements. The total predicted output power was ˜3 kW. Lengthening of the cut-off output taper has demonstrated an improved confinement of the second harmonic signal, facilitating purer output of the fourth harmonic signal. In this enhanced configuration, the predicted output power of the second harmonic was ˜250 W, while the fourth harmonic was ˜15 W. The system demonstrates the potential for selective fourth harmonic generation, for starting currents which are two orders of magnitude lower than would be required for direct excitation.

  2. 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.

  3. 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)

  4. High Power Proton Facilities

    NASA Astrophysics Data System (ADS)

    Nagaitsev, Sergei

    2015-04-01

    This presentation will provide an overview of the capabilities and challenges of high intensity proton accelerators, such as J-PARC, Fermilab MI, SNS, ISIS, PSI, ESS (in the future) and others. The presentation will focus on lessons learned, new concepts, beam loss mechanisms and methods to mitigate them.

  5. TRANSISTOR HIGH VOLTAGE POWER SUPPLY

    DOEpatents

    Driver, G.E.

    1958-07-15

    High voltage, direct current power supplies are described for use with battery powered nuclear detection equipment. The particular advantages of the power supply described, are increased efficiency and reduced size and welght brought about by the use of transistors in the circuit. An important feature resides tn the employment of a pair of transistors in an alternatefiring oscillator circuit having a coupling transformer and other circuit components which are used for interconnecting the various electrodes of the transistors.

  6. 35-GHz 25-kW CW low-voltage third-harmonic gyrotron

    SciTech Connect

    McDermott, D.B.; Balkcum, A.J.; Luhmann, N.C. Jr.

    1996-06-01

    A 50-kV third-harmonic gyrotron is shown to be capable of high efficiency. Operation at the third harmonic allows the required magnetic field for 35 GHz generation to be supplied by a 4.5-kG permanent magnet. Two gyrotrons employing sliced circuits for mode control have been evaluated with a large-signal nonself-consistent particle-tracing simulation code and found to be capable of producing 25 kW continuously. The preliminary design of a third-harmonic TE{sub 41} gyrotron utilizing a magnetron injection electron gun is predicted to yield a device efficiency of 17%, which can potentially be increased to 46% with an ideal single-stage depressed collector, while an axis-encircling electron beam from a Cusp electron gun is predicted to drive a third-harmonic TE{sub 31} gyrotron with a device efficiency of 23%, which can theoretically be increased to 45% through the use of an ideal depressed collector.

  7. 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.

  8. Start-up scenario in gyrotrons with a nonstationary microwave-field structure.

    PubMed

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

    2006-03-31

    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, 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 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. PMID:16605920

  9. On the sensitivity of terahertz gyrotron based systems for remote detection of concealed radioactive materials

    NASA Astrophysics Data System (ADS)

    Nusinovich, G. S.; Sprangle, P.; Semenov, V. E.; Dorozhkina, D. S.; Glyavin, M. Yu

    2012-06-01

    This paper analyzes some features of systems intended to remotely detect concealed radioactive materials by using a focused THz radiation. This concept is based on possibility to focus high-power THz radiation in a small spot where the wave field exceeds the breakdown threshold. However, in the absence of any sources of ionization, the probability to have in this breakdown-prone volume any seed electrons is very low. Thus, high breakdown rate in a series of THz pulses will indicate the presence of concealed radioactive materials in the vicinity of a focused wave beam. The goal of the present paper is to determine by using the statistical theory THz pulse duration required for reliable initiation of the discharge. Then, the detectable mass of the radioactive material is determined as the function of distance and of the THz wave power and pulse duration. Lastly, possible benefits from using pulse compressors, which shorten the pulse duration but increase the wave power and, hence, the breakdown-prone volume, are analyzed. It is shown that the use of pulse compressors can significantly improve the sensitivity of THz gyrotron based systems for remote detection of concealed radioactive materials.

  10. Applications of high power millimeter waves in the DIII-D fusion program

    SciTech Connect

    Freeman, R.L.

    1996-08-01

    First operation of a new generation of MW level, 110 GHz generator (gyrotron) on the DIII-D fusion experimental device has been achieved. The desire for high power, cw millimeter (mm) wave sources to support fusion research and development is just now beginning to be realized. Plasma heating and current drive with directed mm waves rely on the strong absorption achieved when the wave frequency matches the natural ``cyclotron`` frequency of electrons in a magnetic field, or its harmonics. Recent progress in fusion experiments highlights the need for control of the interior details of the hot plasma, and nun wave systems are ideally suited for this role. A brief status of fusion research is given, and the importance of mm waves in the future directions for fusion research is described. The vacuum transmission components necessary for transmitting, monitoring, and launching high power 1 10 GHz waves into a plasma have been developed at General Atomics (GA) and will be described. High power mm waves have a number of attractive technological features for fusion applications compared with other candidate plasma heating and current drive technologies. Millimeter waves can be transmitted with high power density over large distances with low losses by utilizing corrugated waveguides, so the generators can be sited remotely, facilitating maintenance and saving valuable space near the fusion device.

  11. 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.

  12. Experimental results for a 1.5 MW, 110 GHz gyrotron oscillator with reduced mode competition

    SciTech Connect

    Choi, E.M.; Marchewka, C.D.; Mastovsky, I.; Sirigiri, J.R.; Shapiro, M.A.; Temkin, R.J.

    2006-02-15

    A new result from a 110 GHz gyrotron at MIT is reported with an output power of 1.67 MW and an efficiency of 42% when operated at 97 kV and 41 A for 3 {mu}s pulses in the TE{sub 22,6} mode. These results are a major improvement over results obtained with an earlier cavity design, which produced 1.43 MW of power at 37% efficiency. These new results were obtained using a cavity with a reduced output taper angle and a lower ohmic loss when compared with the earlier cavity. The improved operation is shown experimentally to be the result of reduced mode competition from the nearby TE{sub 19,7} mode. The reduced mode competition agrees well with an analysis of the startup scenario based on starting current simulations. The present results should prove useful in planning long pulse and CW versions of the 110 GHz gyrotron.

  13. Spectroscopic temperature measurements of air breakdown plasma using a 110 GHz megawatt gyrotron beam

    SciTech Connect

    Hummelt, J. S.; Shapiro, M. A.; Temkin, R. J.

    2012-12-15

    Temperature measurements are presented of a non-equilibrium air breakdown plasma using optical emission spectroscopy. A plasma is created with a focused 110 GHz 3 {mu}s pulse gyrotron beam in air that produces power fluxes exceeding 1 MW/cm{sup 2}. Rotational and vibrational temperatures are spectroscopically measured over a pressure range of 1-100 Torr as the gyrotron power is varied above threshold. The temperature dependence on microwave field as well as pressure is examined. Rotational temperature measurements of the plasma reveal gas temperatures in the range of 300-500 K and vibrational temperatures in the range of 4200-6200 K. The vibrational and rotational temperatures increase slowly with increasing applied microwave field over the range of microwave fields investigated.

  14. Compact High Power THz Source

    SciTech Connect

    Geoffrey Krafft

    2003-08-01

    In this paper a new type of THz radiation source, based on recirculating an electron beam through a high gradient superconducting radio frequency cavity, and using this beam to drive a standard electromagnetic undulator, is discussed. Because the beam is recirculated, short bunches may be produced that radiate coherently in the undulator, yielding high average THz power for relatively low average beam power. Deceleration from the coherent emission, and the detuning it causes is discussed.

  15. High power solid state lasers

    SciTech Connect

    Weber, H.

    1988-01-01

    These proceedings discuss the following subjects: trends in materials processing with laser radiation; slabs and high power systems; glasses and new crystals; solid state lasers at HOYA Corp.; lamps, resonators and transmission; glasses as active materials for high average power solid state lasers; flashlamp pumped GGG-crystals; alexandrite lasers; designing telescope resonators; mode operation of neodymium: YAG lasers; intracavity frequency doubling with KTP crystal and thermal effects in cylinder lasers.

  16. High average power pockels cell

    DOEpatents

    Daly, Thomas P.

    1991-01-01

    A high average power pockels cell is disclosed which reduces the effect of thermally induced strains in high average power laser technology. The pockels cell includes an elongated, substantially rectangular crystalline structure formed from a KDP-type material to eliminate shear strains. The X- and Y-axes are oriented substantially perpendicular to the edges of the crystal cross-section and to the C-axis direction of propagation to eliminate shear strains.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. High power ferrite microwave switch

    NASA Technical Reports Server (NTRS)

    Bardash, I.; Roschak, N. K.

    1975-01-01

    A high power ferrite microwave switch was developed along with associated electronic driver circuits for operation in a spaceborne high power microwave transmitter in geostationary orbit. Three units were built and tested in a space environment to demonstrate conformance to the required performance characteristics. Each unit consisted of an input magic-tee hybrid, two non-reciprocal latching ferrite phase shifters, an out short-slot 3 db quadrature coupler, a dual driver electronic circuit, and input logic interface circuitry. The basic mode of operation of the high power ferrite microwave switch is identical to that of a four-port, differential phase shift, switchable circulator. By appropriately designing the phase shifters and electronic driver circuits to operate in the flux-transfer magnetization mode, power and temperature insensitive operation was achieved. A list of the realized characteristics of the developed units is given.

  3. Study of a Ka-Band TE11 Mode Gyrotron Traveling-Wave Amplifier

    NASA Astrophysics Data System (ADS)

    Xu, Shou-Xi; Du, Chao-Hai; Liu, Pu-Kun

    2010-05-01

    A Ka-band gyrotron traveling wave (gyro-TWT) amplifier with high power and wide bandwidth operated in the fundamental TE11 circular mode is presented in detail. The stability of the gyro-TWT amplifier using linear and nonlinear theory is analyzed. The distributed loss technique is employed in the interaction circuit which guarantees the amplifier zero-drive stability. The effects of the parameters such as input power, driver frequency, magnetic field on the performance of the gyro-TWT is discussed. The simulation results show that the gain and the bandwidth of the designed Ka-band gyro-TWT are about 60.0 dB and 1.4 GHz at constant drive with an axial velocity spread {{Δ {v_z}} {{v_z}}} = 5% . The peak output power and the corresponding electronic efficiency are about 111 kW and 26.4% respectively for a 70 kV, 6A electron beam at 35 GHz. In addition, the design of the input coupler, a triode-type magnetron injection gun (MIG) and a triple output window are given.

  4. A NEW CROWBAR SYSTEM FOR THE PROTECTION OF HIGH POWER GRIDDED TUBES AND MICROWAVE DEVICES

    SciTech Connect

    S.G.E. PRONKO; T.E.HARRIS

    2001-04-01

    As part of the electron cyclotron heating (ECH) facility upgrade at the DIII-D National Fusion Facility, two 8.4 MW modulator/regulator power systems were designed and constructed (Ref. 1). Each power system uses a high power tetrode to modulate and regulate the cathode voltage for two 1 MW-class 110 GHz gyrotrons (Ref. 2). A critical element in the power system is the fault energy divertor, or crowbar switch, that protects the tetrode and the gyrotrons in the event of an arc fault. Traditionally, mercury filled ignitron switches are used for this application, but it was desired to eliminate hazardous materials and improve overall switching performance. The new crowbar switch system was required to meet the following requirements: Operating voltage: -105 kVdc; Peak current (750 ms e-fold): 1.6 kA; Follow-on current: <1 kA (25 ms); Charge transfer per shot: <15 Cb; and Turn-on time: <1 {micro}s. The switch that was chosen for the new design is a low pressure deuterium filled device, called a metal-arc thyratron, manufactured by Marconi Applied Technologies (Ref. 3). In addition to the new crowbar switch assembly, improved fault signal processing circuitry was developed. This new circuitry uses fiber-optics for signal and trigger transmission and a complex programmable logic device for high speed signal and logic processing. Two generations of metal-arc thyratrons have been commissioned in the two ECH power systems constructed at DIII-D. In the first, the crowbar system performed extremely well, meeting all of the operating requirements and demonstrating its ability to protect a 36 gauge copper wire from fusing (energy let-through <10 J). However, after accumulating over 500 shots, the metal-arc thyratrons lost their ability to reliably hold-off voltage. This problem was solved by Marconi with a design modification of the thyratron electrodes. The second generation tubes were installed in the second ECH power system. The crowbar system was fully commissioned and all

  5. 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.

  6. 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.

  7. G-band harmonic multiplying gyrotron traveling-wave amplifier with a mode-selective circuit

    NASA Astrophysics Data System (ADS)

    Yeh, Y. S.; Chen, Chang-Hong; Wang, Z. W.; Kao, B. H.; Chen, Chien-Hsiang; Lin, T. Y.; Guo, Y. W.

    2014-12-01

    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 TE01 drive wave, the second harmonic component of the beam current initiates a TE02 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 21 , TE 51 , TE 22 , and TE 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.

  8. A High Power Wide-band Gyro-BWO for Terahertz Operation

    NASA Astrophysics Data System (ADS)

    He, Wenlong

    2013-10-01

    Terahertz waves have many exciting applications. If the frequency can be tuned these applications can be greatly enhanced with higher range resolution and improved sensitivity or selectivity. The potential of gyrotron backward wave oscillators (gyro-BWOs) as a high power (kW) coherent powerful microwave source with wide-frequency tunability, has hitherto been achieved only at frequencies well below the terahertz range. This abstract presents the first successful operation of a high power gyro-BWO with a wide frequency tuning capability in the low terahertz frequency range. A novel helically corrugated interaction region (HCIR) and 1.5 A, 40 kV thermionic cusp electron gun were used in the gyro-BWO. An ``ideal'' eigenwave, achieved from the resonant coupling of the modes in the HCIR, allows for broadband microwave amplification or wide frequency tuning. Stable single mode output was achieved in a wide frequency tuning band of 88-102.5 GHz by adjusting the cavity magnetic field with a maximum power of 12 kW and an electronic efficiency of 20%. The performance of the gyro-BWO is consistent with 3D particle-in-cell (PIC) numerical simulations. This method can, in principle, be extended to the higher terahertz range. Thanks Dr. Peter Huggard and his colleagues at the STFC Rutherford Appleton Laboratory, UK for the construction of the HCIR. Supported by UK EPSRC research grant EP/G036659/1.

  9. High Power Amplifier and Power Supply

    NASA Technical Reports Server (NTRS)

    Duong, Johnny; Stride, Scot; Harvey, Wayne; Haque, Inam; Packard, Newton; Ng, Quintin; Ispirian, Julie Y.; Waian, Christopher; Janes, Drew

    2008-01-01

    A document discusses the creation of a high-voltage power supply (HVPS) that is able to contain voltages up to -20 kV, keep electrical field strengths to below 200 V/mil (approximately equal to 7.87 kV/mm), and can provide a 200-nanosecond rise/fall time focus modulator swinging between cathode potential of 16.3 kV and -19.3 kV. This HVPS can protect the 95-GHz, pulsed extended interaction klystron (EIK) from arcs/discharges from all sources, including those from within the EIK fs vacuum envelope. This innovation has a multi-winding pulse transformer design, which uses new winding techniques to provide the same delays and rise/fall times (less than 10 nanoseconds) at different potential levels ranging from -20 kV to -16 kV. Another feature involves a high-voltage printed-wiring board that was corona-free at -20 kV DC with a 3- kV AC swing. The corona-free multilayer high-voltage board is used to simulate fields of less than 200 V/mil (approximately equal to 7.87 kV/mm) at 20 kV DC. Drive techniques for the modulator FETs (field-effect transistors) (four to 10 in a series) were created to change states (3,000-V swing) without abrupt steps, while still maintaining required delays and transition times. The packing scheme includes a potting mold to house a ten-stage modulator in the space that, in the past, only housed a four-stage modulator. Problems keeping heat down were solved using aluminum oxide substrate in the high-voltage section to limit temperature rise to less than 10 while withstanding -20 kV DC voltage and remaining corona-free.

  10. Integrated high power VCSEL systems

    NASA Astrophysics Data System (ADS)

    Moench, Holger; Conrads, Ralf; Gronenborn, Stephan; Gu, Xi; Miller, Michael; Pekarski, Pavel; Pollmann-Retsch, Jens; Pruijmboom, Armand; Weichmann, Ulrich

    2016-03-01

    High power VCSEL systems are a novel laser source used for thermal treatment in industrial manufacturing. These systems will be applied in many applications, which have not used a laser source before. This is enabled by the unique combination of efficiency, compactness and robustness. High power VCSEL system technology encompasses elements far beyond the VCSEL chip itself: i.e. heat sinks, bonding technology and integrated optics. This paper discusses the optimization of these components and processes specifically for building high-power laser systems with VCSEL arrays. New approaches help to eliminate components and process steps and make the system more robust and easier to manufacture. New cooler concepts with integrated electrical and mechanical interfaces have been investigated and offer advantages for high power system design. The bonding process of chips on sub-mounts and coolers has been studied extensively and for a variety of solder materials. High quality of the interfaces as well as good reliability under normal operation and thermal cycling have been realized. A viable alternative to soldering is silver sintering. The very positive results which have been achieved with a variety of technologies indicate the robustness of the VCSEL chips and their suitability for high power systems. Beam shaping micro-optics can be integrated on the VCSEL chip in a wafer scale process by replication of lenses in a polymer layer. The performance of VCSEL arrays with integrated collimation lenses has been positively evaluated and the integrated chips are fully compatible with all further assembly steps. The integrated high power systems make the application even easier and more robust. New examples in laser material processing and pumping of solid state lasers are presented.

  11. Pulsed high-power beams

    SciTech Connect

    Reginato, L.L.; Birx, D.L.

    1988-06-01

    The marriage of induction linac technology with nonlinear magnetic modulators has produced some unique capabilities. It is now possible to produce short-pulse electron beams with average currents measured in amperes, at gradients approaching 1-MeV/m, and with power efficiencies exceeding 50%. A 70-Mev, 3-kA induction accelerator (ETA II) constructed at the Lawrence Livermore National Laboratory incorporates the pulse technology concepts that have evolved over the past several years. The ETA II is a linear induction accelerator and provides a test facility for demonstration of the high-average-power components and high-brightness sources used in such accelerators. The pulse drive for the accelerator is based on state-of-the-art magnetic pulse compressors with very high peak-power capability, repetition rates exceeding 1 kHz, and excellent reliability. 6 figs.

  12. High power excimer laser micromachining

    NASA Astrophysics Data System (ADS)

    Herbst, Ludolf; Paetzel, Rainer

    2006-02-01

    Today's excimer lasers are well-established UV laser sources for a wide variety of micromachining applications. The excimer's high pulse energy and average power at short UV wavelengths make them ideal for ablation of various materials, e. g., polyimide, PMMA, copper, and diamond. Excimer micromachining technology, driven by the ever-shrinking feature sizes of micro-mechanical and micro-electronic devices, is used for making semiconductor packaging microvias, ink jet nozzle arrays, and medical devices. High-power excimer laser systems are capable of processing large areas with resolution down to several microns without using wet chemical processes. For instance, drilling precise tapered holes and reel-to-reel manufacturing of disposable sensors have proven to be very cost-effective manufacturing techniques for volume production. Specifically, the new industrial excimer laser-the LAMBDA SX 315C-easily meets the high demands of cost-effective production. The stabilized output power of 315 watts at 300 Hz (308 nm) and its outstanding long-term stability make this laser ideal for high-duty-cycle, high-throughput micromachining. In this paper, high-power excimer laser technology, products, applications, and beam delivery systems will be discussed.

  13. High-Average Power Facilities

    SciTech Connect

    Dowell, David H.; Power, John G.; /Argonne

    2012-09-05

    There has been significant progress in the development of high-power facilities in recent years yet major challenges remain. The task of WG4 was to identify which facilities were capable of addressing the outstanding R&D issues presently preventing high-power operation. To this end, information from each of the facilities represented at the workshop was tabulated and the results are presented herein. A brief description of the major challenges is given, but the detailed elaboration can be found in the other three working group summaries.

  14. 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.

  15. High-power microwave transmission and mode conversion program. Progress report, June 15, 1993--June 15, 1994

    SciTech Connect

    Vernon, R.J.; Lorbeck, J.A.

    1994-06-01

    This report briefly discusses the following topics: (1) Quasi-optical converter design for Varian gyrotron SN 4.1; (2) Quasi-optical converter cold-test measurement; (3) Modification of geometrical-optics synthesized surfaces; (4)Diffraction synthesis; (5) Tapered dimpled launcher; (6) Work on Vlasov converter system for Varian gyrotron SN 4.1R; (7) Analysis of gyrotron spurious modes; (8) MIT code benchmarking; (9) Development of low-power efficiency test for Vlasov converters; (10) Investigation of optimal beam waist size and mode content for injection into a circular and rectangular corrugated waveguides; (11) The effect of corrugations on reduction of the fields at the wall of waveguides; (12) Shipping of a microwave scanner to Varian and further microwave scanner development; and (13) Code transferred to Varian.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    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.

  17. 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.

  18. Development program for a 200 kW, CW gyrotron. Quarterly report No. 4, April-June 1980

    SciTech Connect

    Tancredi, J.J.; Caplan, M.; Sandoval, J.J.; 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-varyinng rf load mismatch.

  19. High Temperature, High Power Piezoelectric Composite Transducers

    PubMed Central

    Lee, Hyeong Jae; Zhang, Shujun; Bar-Cohen, Yoseph; Sherrit, StewarT.

    2014-01-01

    Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined. PMID:25111242

  20. High temperature, high power piezoelectric composite transducers.

    PubMed

    Lee, Hyeong Jae; Zhang, Shujun; Bar-Cohen, Yoseph; Sherrit, Stewart

    2014-01-01

    Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined. PMID:25111242

  1. High power fast ramping power supplies

    SciTech Connect

    Marneris,I.; Bajon, E.; Bonati, R.; Sandberg, J.; Roser, T.; Tsoupas, N.

    2009-05-04

    Hundred megawatt level fast ramping power converters to drive proton and heavy ion machines are under research and development at accelerator facilities in the world. This is a leading edge technology. There are several topologies to achieve this power level. Their advantages and related issues will be discussed.

  2. High power neutron production targets

    SciTech Connect

    Wender, S.

    1996-06-01

    The author describes issues of concern in the design of targets and associated systems for high power neutron production facilities. The facilities include uses for neutron scattering, accelerator driven transmutation, accelerator production of tritium, short pulse spallation sources, and long pulse spallation sources. Each of these applications requires a source with different design needs and consequently different implementation in practise.

  3. High power, high frequency helix TWT's

    NASA Astrophysics Data System (ADS)

    Sloley, H. J.; Willard, J.; Paatz, S. R.; Keat, M. J.

    The design and performance characteristics of a 34-GHz pulse tube capable of 75 W peak power output at 30 percent duty cycle and a broadband CW tube are presented. Particular attention is given to the engineering problems encountered during the development of the tubes, including the suppression of backward wave oscillation, the design of electron guns for small-diameter high-current beams, and the thermal capability of small helix structures. The discussion also covers the effects of various design parameters and choice of engineering materials on the ultimate practical limit of power and gain at the operating frequencies. Measurements are presented for advanced experimental tubes.

  4. Possible standoff detection of ionizing radiation using high-power THz electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Nusinovich, Gregory S.; Sprangle, Phillip; Romero-Talamas, Carlos A.; Rodgers, John; Pu, Ruifeng; Kashyn, Dmytro G.; Antonsen, Thomas M., Jr.; Granatstein, Victor L.

    2012-06-01

    Recently, a new method of remote detection of concealed radioactive materials was proposed. This method is based on focusing high-power short wavelength electromagnetic radiation in a small volume where the wave electric field exceeds the breakdown threshold. In the presence of free electrons caused by ionizing radiation, in this volume an avalanche discharge can then be initiated. When the wavelength is short enough, the probability of having even one free electron in this small volume in the absence of additional sources of ionization is low. Hence, a high breakdown rate will indicate that in the vicinity of this volume there are some materials causing ionization of air. To prove this concept a 0.67 THz gyrotron delivering 200-300 kW power in 10 microsecond pulses is under development. This method of standoff detection of concealed sources of ionizing radiation requires a wide range of studies, viz., evaluation of possible range, THz power and pulse duration, production of free electrons in air by gamma rays penetrating through container walls, statistical delay time in initiation of the breakdown in the case of low electron density, temporal evolution of plasma structure in the breakdown and scattering of THz radiation from small plasma objects. Most of these issues are discussed in the paper.

  5. Thermal and Structural Analysis of MIG for Gyrotron

    NASA Astrophysics Data System (ADS)

    Singh, Udaybir; Kumar, Anil; Kumar, Nitin; Kumar, Narendra; Raju, R. S.; Purohit, L. P.; Sinha, A. K.

    2011-04-01

    The paper presents the thermal analysis of the Magnetron Injection Gun for 42 GHz, 200 kW gyrotron, which is used to provide a high quality hollow electron beam. The Finite Element Analysis code ANSYS has been used for the thermal and the structural simulation. The thermal analysis of the structure of Magnetron Injection Gun has been carried out to find out the effect of heater temperature required for maintaining more than 1,000°C at cathode emitter surface to get 10 A of beam current. These results have been experimentally verified. The experimental results closely match the ANSYS results. The effect of the radial expansion of the emitter radius on beam quality has also been analyzed.

  6. Recent operating experience with Varian 70 GHz and 140 GHz gyrotrons

    SciTech Connect

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

    1985-01-01

    The design features and initial test results of Varian 70 GHz and 140 GHz CW gyrotrons are presented. The first experimental 140 GHz tube has achieved an output power of 102 kW at 24% efficiency under pulsed conditions in the desired TE031 cavity mode. Further tests aimed at achieving the design goal of 100 kW CW are currently underway. The 70 GHz tube has achieved an output power of 200 kW under pulsed conditions and possesses a wide dynamic range for output power variations. 6 refs., 8 figs.

  7. 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.

  8. High-power fibre lasers

    NASA Astrophysics Data System (ADS)

    Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas

    2013-11-01

    Fibre lasers are now associated with high average powers and very high beam qualities. Both these characteristics are required by many industrial, defence and scientific applications, which explains why fibre lasers have become one of the most popular laser technologies. However, this success, which is largely founded on the outstanding characteristics of fibres as an active medium, has only been achieved through researchers around the world striving to overcome many of the limitations imposed by the fibre architecture. This Review focuses on these limitations, both past and current, and the creative solutions that have been proposed for overcoming them. These solutions have enabled fibre lasers to generate the highest diffraction-limited average power achieved to date by solid-state lasers.

  9. High frequency power distribution system

    NASA Technical Reports Server (NTRS)

    Patel, Mikund R.

    1986-01-01

    The objective of this project was to provide the technology of high frequency, high power transmission lines to the 100 kW power range at 20 kHz frequency. In addition to the necessary design studies, a 150 m long, 600 V, 60 A transmission line was built, tested and delivered for full vacuum tests. The configuration analysis on five alternative configurations resulted in the final selection of the three parallel Litz straps configuration, which gave a virtually concentric design in the electromagnetic sense. Low inductance, low EMI and flexibility in handling are the key features of this configuration. The final design was made after a parametric study to minimize the losses, weight and inductance. The construction of the cable was completed with no major difficulties. The R,L,C parameters measured on the cable agreed well with the calculated values. The corona tests on insulation samples showed a safety factor of 3.

  10. High power gas laser amplifier

    DOEpatents

    Leland, Wallace T.; Stratton, Thomas F.

    1981-01-01

    A high power output CO.sub.2 gas laser amplifier having a number of sections, each comprising a plurality of annular pumping chambers spaced around the circumference of a vacuum chamber containing a cold cathode, gridded electron gun. The electron beam from the electron gun ionizes the gas lasing medium in the sections. An input laser beam is split into a plurality of annular beams, each passing through the sections comprising one pumping chamber.

  11. Comparison of Different Methods for Calculating Gyrotron Quasi-Optical Mode Converters

    NASA Astrophysics Data System (ADS)

    Gashturi, A. P.; Chirkov, A. V.; Denisov, G. G.; Paveliev, A. B.

    2013-01-01

    This paper presents the use of combination of three methods for calculation and synthesis of high-efficiency microwave mode converters, such as radiators of gyrotrons. The analytical method yields immediate estimates of mode converter dimensions, the Scalar Integral Equation (SIE) allows one to synthesize efficiently the optimal profile of the mode converter, and the most accurate Electric Field Integral Equation (EFIE) is used to check all transmission characteristics of the converter including calculations of reflection and cross-polarization. The combination of these three methods is an optimal for the mode converter design. Just so the launcher was designed for a quasi-optical mode converter used in the 60 GHz gyrotron in the TE7,3 operating mode. The simulation results agree well with the measured data. The paper also presents for the first time an accurate derivation of the SIE method.

  12. High-Power Rf Load

    DOEpatents

    Tantawi, Sami G.; Vlieks, Arnold E.

    1998-09-01

    A compact high-power RF load comprises a series of very low Q resonators, or chokes [16], in a circular waveguide [10]. The sequence of chokes absorb the RF power gradually in a short distance while keeping the bandwidth relatively wide. A polarizer [12] at the input end of the load is provided to convert incoming TE.sub.10 mode signals to circularly polarized TE.sub.11 mode signals. Because the load operates in the circularly polarized mode, the energy is uniformly and efficiently absorbed and the load is more compact than a rectangular load. Using these techniques, a load having a bandwidth of 500 MHz can be produced with an average power dissipation level of 1.5 kW at X-band, and a peak power dissipation of 100 MW. The load can be made from common lossy materials, such as stainless steel, and is less than 15 cm in length. These techniques can also produce loads for use as an alternative to ordinary waveguide loads in small and medium RF accelerators, in radar systems, and in other microwave applications. The design is easily scalable to other RF frequencies and adaptable to the use of other lossy materials.

  13. High power, high beam quality regenerative amplifier

    DOEpatents

    Hackel, Lloyd A.; Dane, Clifford B.

    1993-01-01

    A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

  14. High power, high beam quality regenerative amplifier

    DOEpatents

    Hackel, L.A.; Dane, C.B.

    1993-08-24

    A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

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

    PubMed

    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

    2003-02-01

    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 9T (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 20K; in addition, we have observed significant enhancements in 15N spectra of unoriented pf1-bacteriophage. Finally, enhancements of approximately 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. PMID:12615147

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

    PubMed Central

    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.

    2010-01-01

    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 9T (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. PMID:12615147

  17. High Power Free Electron Lasers

    SciTech Connect

    George Neil

    2004-04-12

    FEL Oscillators have been around since 1977 providing not only a test bed for the physics of Free Electron Lasers and electron/photon interactions but as a workhorse of scientific research. The characteristics that have driven the development of these sources are the desire for high peak and average power, high pulse energies, wavelength tunability, timing flexibility, and wavelengths that are unavailable from more conventional laser sources. User programs have been performed using such sources encompassing medicine, biology, solid state research, atomic and molecular physics, effects of non-linear fields, surface science, polymer science, pulsed laser vapor deposition, to name just a few. Recently the incorporation of energy recovery systems has permitted extension of the average power capabilities to the kW level and beyond. Development of substantially higher power systems with applications in defense and security is believed feasible with modest R&D efforts applied to a few technology areas. This paper will discuss at a summary level the physics of such devices, survey existing and planned facilities, and touch on the applications that have driven the development of these popular light sources.

  18. High voltage DC power supply

    DOEpatents

    Droege, T.F.

    1989-12-19

    A high voltage DC power supply having a first series resistor at the output for limiting current in the event of a short-circuited output, a second series resistor for sensing the magnitude of output current, and a voltage divider circuit for providing a source of feedback voltage for use in voltage regulation is disclosed. The voltage divider circuit is coupled to the second series resistor so as to compensate the feedback voltage for a voltage drop across the first series resistor. The power supply also includes a pulse-width modulated control circuit, having dual clock signals, which is responsive to both the feedback voltage and a command voltage, and also includes voltage and current measuring circuits responsive to the feedback voltage and the voltage developed across the second series resistor respectively. 7 figs.

  19. High voltage DC power supply

    DOEpatents

    Droege, Thomas F.

    1989-01-01

    A high voltage DC power supply having a first series resistor at the output for limiting current in the event of a short-circuited output, a second series resistor for sensing the magnitude of output current, and a voltage divider circuit for providing a source of feedback voltage for use in voltage regulation is disclosed. The voltage divider circuit is coupled to the second series resistor so as to compensate the feedback voltage for a voltage drop across the first series resistor. The power supply also includes a pulse-width modulated control circuit, having dual clock signals, which is responsive to both the feedback voltage and a command voltage, and also includes voltage and current measuring circuits responsive to the feedback voltage and the voltage developed across the second series resistor respectively.

  20. 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).

  1. High power cladding light strippers

    NASA Astrophysics Data System (ADS)

    Wetter, Alexandre; Faucher, Mathieu; Sévigny, Benoit

    2008-02-01

    The ability to strip cladding light from double clad fiber (DCF) fibers is required for many different reasons, one example is to strip unwanted cladding light in fiber lasers and amplifiers. When removing residual pump light for example, this light is characterized by a large numerical aperture distribution and can reach power levels into the hundreds of watts. By locally changing the numerical aperture (N.A.) of the light to be stripped, it is possible to achieve significant attenuation even for the low N.A. rays such as escaped core modes in the same device. In order to test the power-handling capability of this device, one hundred watts of pump and signal light is launched from a tapered fusedbundle (TFB) 6+1x1 combiner into a high power-cladding stripper. In this case, the fiber used in the cladding stripper and the output fiber of the TFB was a 20/400 0.06/0.46 N.A. double clad fiber. Attenuation of over 20dB in the cladding was measured without signal loss. By spreading out the heat load generated by the unwanted light that is stripped, the package remained safely below the maximum operating temperature internally and externally. This is achieved by uniformly stripping the energy along the length of the fiber within the stripper. Different adhesive and heat sinking techniques are used to achieve this uniform removal of the light. This suggests that these cladding strippers can be used to strip hundreds of watts of light in high power fiber lasers and amplifiers.

  2. High frequency, high power capacitor development

    NASA Technical Reports Server (NTRS)

    White, C. W.; Hoffman, P. S.

    1983-01-01

    A program to develop a special high energy density, high power transfer capacitor to operate at frequency of 40 kHz, 600 V rms at 125 A rms plus 600 V dc bias for space operation. The program included material evaluation and selection, a capacitor design was prepared, a thermal analysis performed on the design. Fifty capacitors were manufactured for testing at 10 kHz and 40 kHz for 50 hours at Industrial Electric Heating Co. of Columbus, Ohio. The vacuum endurance test used on environmental chamber and temperature plate furnished by Maxwell. The capacitors were energized with a special power conditioning apparatus developed by Industrial Electric Heating Co. Temperature conditions of the capacitors were monitored by IEHCo test equipment. Successful completion of the vacuum endurance test series confirmed achievement of the main goal of producing a capacitor or reliable operation at high frequency in an environment normally not hospitable to electrical and electronic components. The capacitor developed compared to a typical commercial capacitor at the 40 kHz level represents a decrease in size and weight by a factor of seven.

  3. High power, high frequency, vacuum flange

    DOEpatents

    Felker, B.; McDaniel, M.R.

    1993-03-23

    An improved waveguide flange is disclosed for high power operation that helps prevent arcs from being initiated at the junctions between waveguide sections. The flanges at the end of the waveguide sections have counter bores surrounding the waveguide tubes. When the sections are bolted together the counter bores form a groove that holds a fully annealed copper gasket. Each counterbore has a beveled step that is specially configured to insure the gasket forms a metal-to-metal vacuum seal without gaps or sharp edges. The resultant inner surface of the waveguide is smooth across the junctions between waveguide sections, and arcing is prevented.

  4. High power, high frequency, vacuum flange

    DOEpatents

    Felker, Brian; McDaniel, Michael R.

    1993-01-01

    An improved waveguide flange is disclosed for high power operation that helps prevent arcs from being initiated at the junctions between waveguide sections. The flanges at the end of the waveguide sections have counterbores surrounding the waveguide tubes. When the sections are bolted together the counterbores form a groove that holds a fully annealed copper gasket. Each counterbore has a beveled step that is specially configured to insure the gasket forms a metal-to-metal vacuum seal without gaps or sharp edges. The resultant inner surface of the waveguide is smooth across the junctions between waveguide sections, and arcing is prevented.

  5. Recent Advances in High Power Millimeter Wave Gyroklystron Amplifiers at NRL

    NASA Astrophysics Data System (ADS)

    Danly, B. G.

    1998-04-01

    Amplifiers based on the electron cyclotron resonance maser or gyrotron interaction are capable of producing both high peak and high average powers in the millimeter wave band. These devices are of interest for a variety of applications including use in millimeter wave radars and as drivers for high frequency RF accelerators. Recent progress on 35 GHz and 93 GHz gyroklystron and gyrotwystron amplifiers in the Vacuum Electronics Branch of the Naval Research Laboratory will be described. At 35 GHz, a two-cavity device has produced up to 210 kW peak power at 37% efficiency with limited bandwidth( J.J. Choi, A.H. McCurdy, F. Wood, R.H. Kyser, J. Calame, K. Nguyen, B.G. Danly, T.M. Antonsen Jr., B. Levush, and R.K. Parker, Experimental Investigation of a High Power, Two-Cavity, 35 GHz Gyroklystron Amplifier IEEE Trans.Plasma Sci., To Be Published, 1998.), and a three-cavity device has produced up to 225 kW peak power with 0.6% bandwidth. At 93 GHz, successive experimental four-cavity gyroklystrons have produced up to 67 kW with 460 MHz bandwidth and 60 kW with 640 MHz bandwidth(M. Blank, B.G. Danly, B. Levush, P.E. Latham, and D. Pershing, Experimental Demonstration of a W-Band Gyroklystron Amplifier Phys.Rev.Lett., vol. 79, pp. 4485-4488, 1997.). These amplifiers have had gains in the 27 - 30 dB range. The experimental results are in excellent agreement with theoretical predictions. Recent progress will be detailed, and opportunities for higher power and bandwidth will be discussed.

  6. Gyrotron cavity resonator with an improved value of Q

    DOEpatents

    Stone, David S.; Shively, James F.

    1982-10-26

    A gyrotron cavity resonator is connected smoothly and directly to an output waveguide with a very gradually tapered wall so that values of external Q lower than twice the diffraction limit are obtainable.

  7. 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.

  8. Development of a dual frequency (110/138 GHz) gyrotron for JT-60SA and its extension to an oscillation at 82 GHz

    NASA Astrophysics Data System (ADS)

    Kobayashia, Takayuki; Moriyama, Shinichi; Isayama, Akihiko; Sawahata, Masayuki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Sato, Yoshikatsu; Hinata, Jun; Yokokura, Kenji; Hoshino, Katsumichi; Sakamoto, Keishi

    2015-03-01

    A dual-frequency gyrotron, which can generate 110 GHz and 138 GHz waves independently, is being developed in JAEA to enable electron cyclotron heating (ECH) and current drive (ECCD) in a wider range of plasma discharge conditions of JT-60SA. Conditioning operation of the gyrotron toward 1 MW for 100 s, which is the target output power and pulse length for JT-60SA, is in progress without significant problems. Oscillations of 1 MW for 10 s and 0.5 MW for 198 s were obtained, so far, at both frequencies. Cooling water temperatures in the gyrotron and matching optics unit were saturated in the 198 s oscillation, and the observed maximum water temperature is sufficiently low. In addition to the above activity on the dual-frequency gyrotron development, an oscillation (0.3 MW for 20 ms) at 82 GHz was demonstrated as an additional frequency of the dual-frequency gyrotron. A possibility of the use of fundamental harmonic wave at 82 GHz in JT-60SA has been shown.

  9. Improved Programmable High-Voltage Power Supply

    NASA Technical Reports Server (NTRS)

    Castell, Karen; Rutberg, Arthur

    1994-01-01

    Improved dc-to-dc converter functions as programmable high-voltage power supply with low-power-dissipation voltage regulator on high-voltage side. Design of power supply overcomes deficiencies of older designs. Voltage regulation with low power dissipation provided on high-voltage side.

  10. High-power pulsed lasers

    SciTech Connect

    Holzrichter, J.F.

    1980-04-02

    The ideas that led to the successful construction and operation of large multibeam fusion lasers at the Lawrence Livermore Laboratory are reviewed. These lasers are based on the use of Nd:glass laser materials. However, most of the concepts are applicable to any laser being designed for fusion experimentation. This report is a summary of lectures given by the author at the 20th Scottish University Summer School in Physics, on Laser Plasma Interaction. This report includes basic concepts of the laser plasma system, a discussion of lasers that are useful for short-pulse, high-power operation, laser design constraints, optical diagnostics, and system organization.

  11. High power microwave source development

    NASA Astrophysics Data System (ADS)

    Benford, James N.; Miller, Gabriel; Potter, Seth; Ashby, Steve; Smith, Richard R.

    1995-05-01

    The requirements of this project have been to: (1) improve and expand the sources available in the facility for testing purposes and (2) perform specific tasks under direction of the Defense Nuclear Agency about the applications of high power microwaves (HPM). In this project the HPM application was power beaming. The requirements of this program were met in the following way: (1) We demonstrated that a compact linear induction accelerator can drive HPM sources at repetition rates in excess of 100 HZ at peak microwave powers of a GW. This was done for the relativistic magnetron. Since the conclusion of this contract such specifications have also been demonstrated for the relativistic klystron under Ballistic Missile Defense Organization funding. (2) We demonstrated an L band relativistic magnetron. This device has been used both on our single pulse machines, CAMEL and CAMEL X, and the repetitive system CLIA. (3) We demonstrated that phase locking of sources together in large numbers is a feasible technology and showed the generation of multigigawatt S-band radiation in an array of relativistic magnetrons.

  12. Electron dynamics in the process of mode switching in gyrotrons

    SciTech Connect

    Dumbrajs, O.; Kominis, Y.; Nusinovich, G. S.

    2009-01-15

    The present paper is devoted to the analysis of electron interaction process in the course of gyrotron switching from one mode to another. This analysis is based on the use of the Hamiltonian formalism that allows one to construct Poincare plots for different instants of switching time. The study is carried out for a 170 GHz, MW-class gyrotron for the International Thermonuclear Experimental Reactor (ITER) [ITER web site: http://www.iter.org].

  13. High-power microwave transmission systems for electron-cyclotron-resonance plasma heating

    SciTech Connect

    Vernon, R.J.

    1991-08-01

    This progress report is for the sixth year of a grant from the US Department of Energy for the design, development, and fabrication of ECRH transmission and mode conversion systems to transport microwave power from a gyrotron to a magnetically confined plasma. The design and low-power testing of new and improved components for such systems and development of underlying theory is the focus of this project. Devising and improving component testing and diagnostic techniques is also an important part of this effort. The development of possible designs for sections of gyrotrons themselves, such as tapers or Vlasov-type launchers, in support of the Varian gyrotron development program is also considered when appropriate. We also provide support to other groups working on ECR heating of magnetically confined plasmas such as the groups at General Atomics, the University of Texas at Austin, and Lawrence Livermore National Laboratory. During the last year, we designed and had fabricated a two-dimensional Vlasov antenna system for a 110 GHz TE{sub 15,2} mode gyrotron for possible use at General Atomics. The system included the launcher section, a visor, main reflector, and focusing reflector. Programs to generate the tool-path profiles to cut the General Atomics'' Vlasov components on a milling machine were developed. We have also developed state-of-the art theory and programs for three-dimensional whispering-gallery-mode Vlasov antenna systems. A design for a 110 GHz TE{sub 01}-TE{sub 15,2} mode converter system for cold testing WGM Vlasov antenna systems was developed and is currently being fabricated also.

  14. 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.

  15. Plasma Physics Challenges of MM-to-THz and High Power Microwave Generation

    NASA Astrophysics Data System (ADS)

    Booske, John

    2007-11-01

    Homeland security and military defense technology considerations have stimulated intense interest in mobile, high power sources of millimeter-wave to terahertz regime electromagnetic radiation, from 0.1 to 10 THz. While sources at the low frequency end, i.e., the gyrotron, have been deployed or are being tested for diverse applications such as WARLOC radar and active denial systems, the challenges for higher frequency sources have yet to be completely met for applications including noninvasive sensing of concealed weapons and dangerous agents, high-data-rate communications, and high resolution spectroscopy and atmospheric sensing. The compact size requirements for many of these high frequency sources requires miniscule, micro-fabricated slow wave circuits with high rf ohmic losses. This necessitates electron beams with not only very small transverse dimensions but also very high current density for adequate gain. Thus, the emerging family of mm-to-THz e-beam-driven vacuum electronics devices share many of the same plasma physics challenges that currently confront ``classic'' high power microwave (HPM) generators [1] including bright electron sources, intense beam transport, energetic electron interaction with surfaces and rf air breakdown at output windows. Multidimensional theoretical and computational models are especially important for understanding and addressing these challenges. The contemporary plasma physics issues, recent achievements, as well as the opportunities and outlook on THz and HPM will be addressed. [1] R.J. Barker, J.H. Booske, N.C. Luhmann, and G.S. Nusinovich, Modern Microwave and Millimeter-Wave Power Electronics (IEEE/Wiley, 2005).

  16. High Power, High Voltage Electric Power System for Electric Propulsion

    NASA Technical Reports Server (NTRS)

    Aintablian, Harry; Kirkham, Harold; Timmerman, Paul

    2006-01-01

    This paper provides an overview of the 30 KW, 600 V MRHE power subsystem. Descriptions of the power subsystem elements, the mode of power transfer, and power and mass estimates are presented. A direct-drive architecture for electric propulsion is considered which reduces mass and complexity. Solar arrays with concentrators are used for increased efficiency. Finally, the challenges due to the environment of a hypothetical lunar mission as well as due to the advanced technologies considered are outlined.

  17. High power density spray cooling

    NASA Astrophysics Data System (ADS)

    Tilton, Donald E.; Pais, Martin R.; Chow, Louis C.

    1989-07-01

    The research reported describes experimental and theoretical investigations of high power density evaporative spray cooling. Preliminary experiments demonstrating heat fluxes greater than 1,000 W/sq cm were conducted. Extensive laser phase Doppler measurements of spray characteristics were also taken. These measurements provided valuable insight into the heat transfer process. An in-depth analysis was conducted to determine the mechanisms responsible for critical heat flux. Theoretical modeling was also conducted to determine the most desirable heat transfer conditions. After analysis of these results, an improved experimental apparatus was designed and fabricated. The new apparatus provided greater experimental control and improve accuracy. New tests were conducted in which the critical heat flux was increased, and the heat transfer efficiency was greatly improved. These results are compared to those of previous researchers, and indicated substantial improvement.

  18. Multimegawatt relativistic harmonic gyrotron traveling-wave tube amplifier experiments

    SciTech Connect

    Menninger, W.L.; Danly, B.G.; Temkin, R.J.

    1996-06-01

    The first multimegawatt harmonic relativistic gyrotron traveling-wave tube (gyro-twt) amplifier experiment has been designed, built, and tested. Results from this experimental setup, including the first ever reported third-harmonic gyro-twt results, are presented. Operation frequency is 17.1 GHz. Detailed phase measurements are also presented. The electron beam source is SNOMAD-II, a solid-state nonlinear magnetic accelerator driver with nominal parameters of 400 kV and 350 A. The flat-top pulsewidth is 30 ns. The electron beam is focused using a Pierce geometry and then imparted with transverse momentum using a bifilar helical wiggler magnet. Experimental operation involving both a second-harmonic interaction with the TE{sub 21} mode and a third-harmonic interaction with the TE{sub 31} mode, both at 17 GHz, has been characterized. The third-harmonic interaction resulted in 4-MW output power and 50-dB single-pass gain, with an efficiency of up to {approximately}8%. The best measured phase stability of the TE{sub 31} amplified pulse was {+-}10{degree} over a 9-ns period. The phase stability was limited because the maximum RF power was attained when operating far from wiggler resonance. The second harmonic, TE{sub 21} had a peak amplified power of 2 MW corresponding to 40-dB single-pass gain and 4% efficiency. The second-harmonic interaction showed stronger superradiant emission than the third-harmonic interaction. Characterizations of the second- and third-harmonic gyro-twt experiments presented here include measurement of far-field radiation patterns, gain and phase versus interaction length, phase stability, and output power versus input power.

  19. Optics assembly for high power laser tools

    DOEpatents

    Fraze, Jason D.; Faircloth, Brian O.; Zediker, Mark S.

    2016-06-07

    There is provided a high power laser rotational optical assembly for use with, or in high power laser tools for performing high power laser operations. In particular, the optical assembly finds applications in performing high power laser operations on, and in, remote and difficult to access locations. The optical assembly has rotational seals and bearing configurations to avoid contamination of the laser beam path and optics.

  20. High power laser apparatus and system

    NASA Technical Reports Server (NTRS)

    Evans, J. C., Jr.; Brandhorst, H. W., Jr. (Inventor)

    1975-01-01

    A high-power, continuous-wave laser was designed for use in power transmission and energy-collecting systems, and for producing incoherent light for pumping a laser material. The laser has a high repetitive pulsing rate per unit time, resulting in a high-power density beam. The laser is composed of xenon flash tubes powered by fast-charging capacitors flashed in succession by a high-speed motor connected to an automobile-type distributor.

  1. Initial tests and operation of a 110 GHz, 1 MW gyrotron with evacuated waveguide system on the DIII-D tokamak

    SciTech Connect

    Lohr, J.; Ponce, D.; Tooker, J.F.

    1996-08-01

    A gyrotron producing nominally 1 MW at 110 GHz has been installed at the DIII-D tokamak and operated in a program of initial tests with a windowless evacuated transmission line. The alignment and first test operation were performed in an air environment at atmospheric pressure. Under these conditions, the tube produced rf output in excess of 800 kW for pulse lengths greater than 10 msec and power near 500 kW for pulse lengths of about 100 msec into a free space dummy load. The gyrotron was operated into evacuated corrugated waveguide in the full power parameter regime for pulse lengths of up to 500 msec injecting greater than 0.5 MW into DIII-D for a preliminary series of experiments. Generated powers greater than 900 kW were achieved. A parasitic oscillation at various frequencies between 20 and 100 MHz, which was generated during the pulsing of the gyrotron electron beam, was suppressed somewhat by a capacitive filter attached to the gyrotron itself. Addition of a magnetic shield intended to alter the magnetic field geometry below the cathode eliminated internal tube sparks. Rework of the external power and interlock circuitry to improve the immunity to electromagnetic interference was also done in parallel so that the fast interlock circuitry could be used. The latest results of the test program, the design of the free space load and other test hardware, and the transmission line will be presented.

  2. 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.

  3. Particle simulation of a ka-band gyrotron traveling wave amplifier

    SciTech Connect

    Xu Shouxi; Liu Pukun; Zhang Shichang; Du Chaohai; Xue Qianzhong; Geng Zhihui; Su Yinong

    2011-08-15

    The design of a ka-band gyrotron traveling wave (gyro-TWT) amplifier is presented. The gyro-TWT amplifier with a severed structure operates in the fundamental harmonic TE{sub 01} circular electric mode. The beam-wave interaction is studied by using a particle-in-cell (PIC) code. The simulations predict that the amplifier can produce an output peak power of over 155 kW, 22% efficiency, 23 dB gain, and a 3 dB bandwidth of 2 GHz for a 70 kV, 10 A electron beam with an axial velocity spread {Delta}v{sub z}/v{sub z}=5%.

  4. 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.

  5. High power ion thruster performance

    NASA Technical Reports Server (NTRS)

    Rawlin, Vincent K.; Patterson, Michael J.

    1987-01-01

    The ion thruster is one of several forms of space electric propulsion being considered for use on future SP-100-based missions. One possible major mission ground rule is the use of a single Space Shuttle launch. Thus, the mass in orbit at the reactor activation altitude would be limited by the Shuttle mass constraints. When the spacecraft subsystem masses are subtracted from this available mass limit, a maximum propellant mass may be calculated. Knowing the characteristics of each type of electric thruster allows maximum values of total impulse, mission velocity increment, and thrusting time to be calculated. Because ion thrusters easily operate at high values of efficiency (60 to 70%) and specific impulse (3000 to 5000 sec), they can impart large values of total impulse to a spacecraft. They also can be operated with separate control of the propellant flow rate and exhaust velocity. This paper presents values of demonstrated and projected performance of high power ion thrusters used in an analysis of electric propulsion for an SP-100 based mission.

  6. Numerical studies of filamentary plasma formation in high power millimeter wave field

    NASA Astrophysics Data System (ADS)

    Takeichi, Tensei; Yamaguchi, Toshikazu; Fukunari, Masafumi; Koizumi, Hiroyuki; Komurasaki, Kimiya; Arakawa, Yoshihiro

    2012-10-01

    Filamentary structure characterizes millimeter-wave discharge in air and the ionization front propagates at supersonic speed in a high power millimeter-wave, generating a shock wave. In this study, the filamentary structure was studied experimentally and analytically using a 170GHz Gyrotron at the peak intensity range of 50 kW/cm^2 to 200kW/cm^2. On the propagation process of ionization front, it is important to investigate steady plasma formation process in a filamentary form through millimeter wave. Each filamentary element observed in the ionization front propagates not along or perpendicular to the electric field, but obliquely. To solve this mechanism, 2-dimensional numerical analysis was conducted assuming this phenomenon as a plasma fluid model. In dozens of times the size of plasma element scale, the steady plasma structure formation was simulated, and the calculation was compared with previous experimental results. The calculated formation patterns were in good qualitative agreement with experiments. The calculation model provides a physical interpretation of the pattern formation and dynamics. From the interpretation, it was found that accurate ionization model in low electric field is needed for good agreement with experiments. Moreover, for a quantitative agreement, not only the ionization model but also consideration of 3-dimensional effects are necessary, since 2-dimensional simulation cannot estimate accurate wave reflection and interaction by plasma.

  7. 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.

  8. Simplified High-Power Inverter

    NASA Technical Reports Server (NTRS)

    Edwards, D. B.; Rippel, W. E.

    1984-01-01

    Solid-state inverter simplified by use of single gate-turnoff device (GTO) to commutate multiple silicon controlled rectifiers (SCR's). By eliminating conventional commutation circuitry, GTO reduces cost, size and weight. GTO commutation applicable to inverters of greater than 1-kilowatt capacity. Applications include emergency power, load leveling, drives for traction and stationary polyphase motors, and photovoltaic-power conditioning.

  9. The K(a)-band 10-kW continuous wave gyrotron with wide-band fast frequency sweep.

    PubMed

    Glyavin, M; Luchinin, A; Morozkin, M

    2012-07-01

    The dual-frequency gyrotron with fast 2% frequency sweep at about 28 GHz is designed to power an electron cyclotron resonance ion source (ECRIS). Operation with an output power of up to 10 kW in CW mode and efficiency of 20% was demonstrated at both frequencies. Frequency manipulation has a characteristic time of about 1 ms and is based on magnetic field variation with an additional low-power coil. Fast frequency sweep will supposedly increase the ion current and the average ion charge of ECRIS. The possibility of 100% power modulation is demonstrated using the same control method. PMID:22852711

  10. The Ka-band 10-kW continuous wave gyrotron with wide-band fast frequency sweep

    NASA Astrophysics Data System (ADS)

    Glyavin, M.; Luchinin, A.; Morozkin, M.

    2012-07-01

    The dual-frequency gyrotron with fast 2% frequency sweep at about 28 GHz is designed to power an electron cyclotron resonance ion source (ECRIS). Operation with an output power of up to 10 kW in CW mode and efficiency of 20% was demonstrated at both frequencies. Frequency manipulation has a characteristic time of about 1 ms and is based on magnetic field variation with an additional low-power coil. Fast frequency sweep will supposedly increase the ion current and the average ion charge of ECRIS. The possibility of 100% power modulation is demonstrated using the same control method.

  11. Development of High Power Electron Beam Measuring and Analyzing System for Microwave Vacuum Electron Devices

    NASA Astrophysics Data System (ADS)

    Ruan, C. J.; Wu, X. L.; Li, Q. S.; Li, C. S.

    The measurement and analysis of high power electron beam during its formation and transmission are the basic scientific problems and key techniques for the development of high performance microwave vacuum electron devices, which are widely used in the fields of military weapon, microwave system and scientific instruments. In this paper, the dynamic parameters measurement and analysis system being built in Institute of Electronics, Chinese Academy of Sciences (IECAS) recently are introduced. The instrument are designed to determine the cross-section, the current density, and the energy resolution of the high power electron beam during its formation and transmission process, which are available both for the electron gun and the electron optics system respectively. Then the three dimension trajectory images of the electron beam can be rebuilt and display with computer controlled data acquisition and processing system easily. Thus, much more complicated structures are considered and solved completely to achieve its detection and analysis, such as big chamber with 10-6 Pa high vacuum system, the controlled detector movement system in axis direction with distance of 600 mm inside the vacuum chamber, the electron beam energy analysis system with high resolution of 0.5%, and the electron beam cross-section and density detector using the YAG: Ce crystal and CCD imaging system et al. At present, the key parts of the instrument have been finished, the cross-section experiment of the electron beam have been performed successfully. Hereafter, the instrument will be used to measure and analyze the electron beam with the electron gun and electron optics system for the single beam and multiple beam klystron, gyrotron, sheet beam device, and traveling wave tube etc. thoroughly.

  12. Rotary high power transfer apparatus

    NASA Technical Reports Server (NTRS)

    Jacobson, Peter E. (Inventor); Porter, Ryan S. (Inventor)

    1987-01-01

    An apparatus for reducing terminal-to-terminal circuit resistance and enhancing heat transfer in a rotary power transfer apparatus of the roll ring type comprising a connecting thimble for attaching an external power cable to a cone shaped terminal which is attached to a tab integral to an outer ring. An inner ring having a spherical recess mates with the spherical end of a tie connector. A cone shaped terminal is fitted to a second connecting thimble for attaching a second external power cable.

  13. Relativistic Harmonic Gyrotron Traveling-Wave Tube Amplifier Experiments.

    NASA Astrophysics Data System (ADS)

    Menninger, William Libbey

    1995-01-01

    The first multi-megawatt (4 MW, eta = 8%) harmonic (omega = sOmega _{c}, s = 2 or 3) relativistic gyrotron traveling-wave tube amplifier (gyro-twt) experiment has been designed, built, and tested. Results from this experimental setup, including the first ever reported third harmonic gyro-twt results, are presented. The first detailed phase measurements of a gyro-twt are also reported. The electron beam source is SNOMAD-II, a solid-state nonlinear magnetic accelerator driver with nominal parameters of 400 kV and 350 A. The flat-top pulse width is 30 ns. The electron beam is focused using a Pierce geometry and then imparted with transverse momentum using a bifilar helical wiggler magnet. The imparted beam pitch is alpha equivbeta_bot/beta_ |~1. Experimental operation involving both a second harmonic interaction with the TE_{21 } mode and a third harmonic interaction with the TE_{31} mode has been characterized. The third harmonic interaction resulted in 4 MW output power and 50 dB single-pass gain, with an efficiency of up to ~8% (for 115 A beam current). The best measured phase stability of the TE_{31} amplified pulse was +/-10^circ over a 9 ns period. The phase stability was limited because the maximum rf power was attained when operating far from wiggler resonance. The second harmonic, TE_ {21} had a peak amplified power of 2 MW corresponding to 40 dB single-pass gain and 4% efficiency. The second harmonic interaction showed stronger superradiant emission than the third harmonic interaction. Characterizations of the second and third harmonic gyro-twt experiments presented in this thesis include measurement of far-field radiation patterns, gain and phase versus interaction length, frequency spectrum, phase, and output power versus input power. The absolute power measurements are based both on angular radiation scans with a calibrated horn and diode, and on propagation of the TE_{31} mode through an efficient in-guide converter and measurement of the converted TE

  14. Possibilities for reducing the aftercavity interaction effect in gyrotrons

    SciTech Connect

    Sinitsyn, O. V.; Nusinovich, G. S.; Antonsen, T. M. Jr.

    2010-08-15

    This paper addresses the problem of aftercavity interaction in gyrotrons. The term ''aftercavity interaction'' is used for the cyclotron resonance interaction between electrons in a spent beam exiting the microwave cavity and traveling electromagnetic waves propagating from the cavity exit into the output part of a gyrotron. Aftercavity interaction may reduce the interaction efficiency by several percent and spoil the energy distribution of spent electrons, thus reducing the possibility of efficient utilization of depressed collectors. We have used a simple theory to find conditions resulting in the reduction of this effect. In particular, we have shown that both the axial waveguide wall profile and magnetic field distribution should be modified in order to weaken the effect of aftercavity interaction. We verified results of our simple analysis with advanced simulations and demonstrated that they are in good agreement. Result of these studies can be beneficial for the gyrotron efficiency enhancement.

  15. Field Formation in the Interaction Space of Gyrotrons

    NASA Astrophysics Data System (ADS)

    Nusinovich, Gregory S.; Dumbrajs, Olgierd

    2016-01-01

    For gyrotron applications in plasma installations, one of the most important factors is the gyrotron efficiency. To maximize the interaction efficiency, it is necessary not only to optimize such operating parameters as the magnetic field, beam voltage, and current but also the axial profile of the electromagnetic (EM) field in the interaction space. The present paper describes a study of the effect of the profile of an irregular waveguide serving as a resonator on the axial structure of the EM field. Specific attention is paid to the profile of the uptaper connecting the regular part of a resonator to the output waveguide. Conditions of applicability of the nonuniform string equation, which is widely used in gyrotron designs for finding the axial structure of the EM field, are discussed. Also discussed are the occurrence of reflections from a smooth uptaper and the analogy between the nonuniform string equation and the stationary Schrodinger equation.

  16. High power RF solid state power amplifier system

    NASA Technical Reports Server (NTRS)

    Sims, III, William Herbert (Inventor); Chavers, Donald Gregory (Inventor); Richeson, James J. (Inventor)

    2011-01-01

    A high power, high frequency, solid state power amplifier system includes a plurality of input multiple port splitters for receiving a high-frequency input and for dividing the input into a plurality of outputs and a plurality of solid state amplifier units. Each amplifier unit includes a plurality of amplifiers, and each amplifier is individually connected to one of the outputs of multiport splitters and produces a corresponding amplified output. A plurality of multiport combiners combine the amplified outputs of the amplifiers of each of the amplifier units to a combined output. Automatic level control protection circuitry protects the amplifiers and maintains a substantial constant amplifier power output.

  17. Status of high power electric propulsion technology

    NASA Technical Reports Server (NTRS)

    Byers, David C.; Stone, James R.

    1988-01-01

    The growing emphasis on very challenging missions and the anticipated availability of high power levels in space have led to renewed interest in high power electric propulsion. The status of high power electric propulsion technology and its applicability to various missions are reviewed. The major thruster and system technology issues are identified which must be addressed in a focussed program in order to assure technology readiness for these missions.

  18. High-Power Electromagnetic Thruster Being Developed

    NASA Technical Reports Server (NTRS)

    LaPointe, Michael R.; Mikellides, Pavlos G.

    2001-01-01

    High-power electromagnetic thrusters have been proposed as primary in-space propulsion options for several bold new interplanetary and deep-space missions. As the lead center for electric propulsion, the NASA Glenn Research Center designs, develops, and tests high-power electromagnetic technologies to meet these demanding mission requirements. Two high-power thruster concepts currently under investigation by Glenn are the magnetoplasmadynamic (MPD) thruster and the Pulsed Inductive Thruster (PIT).

  19. Phase locking and bandwidth in a gyrotron oscillator

    NASA Technical Reports Server (NTRS)

    Latham, P. E.; Granatstein, V. L.; Carmel, Y.

    1993-01-01

    For imaging radar and for satellite and space communication (e.g. NASA's deep space network), it is important that the bandwidth be as large as possible. Here we derive a formalism for computing the phase locking bandwidth that can be achieved in a gyrotron oscillator while varying the beam voltage. As an example, a second harmonic TE02/03 gyrotron is considered. For this device, the effective bandwidth can be increased by a factor of about 3 compared with the fixed voltage case by allowing the beam voltage to change together with the input locking signal.

  20. Mode switching in a gyrotron with azimuthally corrugated resonator.

    PubMed

    Nusinovich, G S; Sinitsyn, O V; Antonsen, T M

    2007-05-18

    The operation of a gyrotron having a cylindrical resonator with an azimuthally corrugated wall is analyzed. In such a device, wall corrugation cancels the degeneracy of the modes with azimuthally standing patterns. The coupling between these modes depends on the radius of electron beam. It is shown that such a gyrotron can be easily switched from one mode to another. When the switching is done with the repetition frequency equal to the rotational frequency of magnetic islands, this sort of operation can be used for suppression of neoclassical tearing modes in large-scale tokamaks and stellarators. PMID:17677705

  1. Mode Switching in a Gyrotron with Azimuthally Corrugated Resonator

    SciTech Connect

    Nusinovich, G. S.; Sinitsyn, O. V.; Antonsen, T. M. Jr.

    2007-05-18

    The operation of a gyrotron having a cylindrical resonator with an azimuthally corrugated wall is analyzed. In such a device, wall corrugation cancels the degeneracy of the modes with azimuthally standing patterns. The coupling between these modes depends on the radius of electron beam. It is shown that such a gyrotron can be easily switched from one mode to another. When the switching is done with the repetition frequency equal to the rotational frequency of magnetic islands, this sort of operation can be used for suppression of neoclassical tearing modes in large-scale tokamaks and stellarators.

  2. Analysis of the harmonic gyrotron traveling wave amplifier

    NASA Technical Reports Server (NTRS)

    Kuo, S. P.; Kuo, S. C.; Cheo, B. R.; Lee, M. C.

    1986-01-01

    A single nonlinear differential equation is derived for describing the spatial evolution of the wave field in a gyrotron amplifier on the cylindrical guide geometry. The equation is then used to determine the efficiencies and the optimized interaction lengths for gyrotron operated with TE sub N1 modes at the N-th cyclotron harmonic. The equation offers a significant advantage in simplifying numerical work in comparison with the brute force particle simulation approach. The efficiencies of the harmonic operations by using a hollow beam decrease quickly with increasing harmonic number, but are enhanced by using an axis-encircling beam instead.

  3. High average power induction accelerators

    SciTech Connect

    Swingle, J.C.

    1985-10-01

    The induction accelerator is discussed with respect to general background and concept, beam transport, scaling, pulse power technology, and the electron beam injector. A discussion of the factors which affect the scaling of the intensity of the beam is given. Limiting factors include collective forces in the beam, virtual cathode formation, surroundings, and beam breakup instability. 24 refs., 11 figs. (WRF)

  4. A High Power Frequency Doubled Fiber Laser

    NASA Technical Reports Server (NTRS)

    Thompson, Robert J.; Tu, Meirong; Aveline, Dave; Lundblad, Nathan; Maleki, Lute

    2003-01-01

    This viewgraph presentation reports on the development of a high power 780 nm laser suitable for space applications of laser cooling. A possible solution is to use frequency doubling of high power 1560 nm telecom lasers. The presentation shows a diagram of the frequency conversion, and a graph of the second harmonic generation in one crystal, and the use of the cascading crystals. Graphs show the second harmonic power as a function of distance between crystals, second harmonic power vs. pump power, tunability of laser systems.

  5. 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.

  6. Linear and time-dependent behavior of the gyrotron backward-wave oscillator.

    PubMed

    Chen, S H; Chang, T H; Pao, K F; Fan, C T; Chu, K R

    2002-12-23

    Formation of axial modes in the gyrotron backward-wave oscillator is examined in the perspective of optimum conditions for beam-wave interactions. Distinctive linear properties are revealed and interpreted physically. Nonlinear implications of these properties (specifically, the role of high-order axial modes) are investigated with time-dependent simulations. Nonstationary oscillations exhibit self-modulation behavior while displaying no evidence of axial mode competition. Reasons for the erratic frequency tuning are investigated and stable tuning regimes are identified as a remedy. PMID:12484861

  7. Stability study of a gyrotron-traveling-wave amplifier based on a lossy dielectric-loaded mode-selective circuit

    SciTech Connect

    Du Chaohai; Liu Pukun

    2009-07-15

    The millimeter microwave source of gyrotron-traveling-wave amplifier (gyro-TWT) is capable of generating high power coherent radiation in a broad bandwidth, while its performance is severely deteriorated by the stability problems. This paper focuses on modeling and the stability analysis of the Naval Research Laboratory (NRL) Ka-band TE{sub 01} mode gyro-TWT based on an interaction circuit alternately loaded with lossy ceramic shells and metal rings. The propagation characteristics of the interaction circuit is analyzed first, based on which the boundary impedance method is employed to build an equivalent uniform lossy circuit. Then the stability of the interaction system is studied using linear and nonlinear theories. The analysis reveals that, due to the special waveguide structure and the dielectric loss, the propagation characteristics of the complex waveguide are similar to that of a uniform lossy circuit. The analysis of the absolute instabilities characterizes the roles the forward-backward-wave components played. The study indicates that the lowest threshold current of the absolute instabilities is higher than the operating current, which brings the system high stability. The reliability of the analysis is proved by the consistency between the analysis and the NRL experimental results.

  8. High Average Power Yb:YAG Laser

    SciTech Connect

    Zapata, L E; Beach, R J; Payne, S A

    2001-05-23

    We are working on a composite thin-disk laser design that can be scaled as a source of high brightness laser power for tactical engagement and other high average power applications. The key component is a diffusion-bonded composite comprising a thin gain-medium and thicker cladding that is strikingly robust and resolves prior difficulties with high average power pumping/cooling and the rejection of amplified spontaneous emission (ASE). In contrast to high power rods or slabs, the one-dimensional nature of the cooling geometry and the edge-pump geometry scale gracefully to very high average power. The crucial design ideas have been verified experimentally. Progress this last year included: extraction with high beam quality using a telescopic resonator, a heterogeneous thin film coating prescription that meets the unusual requirements demanded by this laser architecture, thermal management with our first generation cooler. Progress was also made in design of a second-generation laser.

  9. An explosively driven high-power microwave pulsed power system

    NASA Astrophysics Data System (ADS)

    Elsayed, M. A.; Neuber, A. A.; Dickens, J. C.; Walter, J. W.; Kristiansen, M.; Altgilbers, L. L.

    2012-02-01

    The increased popularity of high power microwave systems and the various sources to drive them is the motivation behind the work to be presented. A stand-alone, self-contained explosively driven high power microwave pulsed power system has been designed, built, and tested at Texas Tech University's Center for Pulsed Power and Power Electronics. The system integrates four different sub-units that are composed of a battery driven prime power source utilizing capacitive energy storage, a dual stage helical flux compression generator as the main energy amplification device, an integrated power conditioning system with inductive energy storage including a fast opening electro-explosive switch, and a triode reflex geometry virtual cathode oscillator as the microwave radiating source. This system has displayed a measured electrical source power level of over 5 GW and peak radiated microwaves of about 200 MW. It is contained within a 15 cm diameter housing and measures 2 m in length, giving a housing volume of slightly less than 39 l. The system and its sub-components have been extensively studied, both as integrated and individual units, to further expand on components behavior and operation physics. This report will serve as a detailed design overview of each of the four subcomponents and provide detailed analysis of the overall system performance and benchmarks.

  10. Test facilities for high power electric propulsion

    NASA Technical Reports Server (NTRS)

    Sovey, James S.; Vetrone, Robert H.; Grisnik, Stanley P.; Myers, Roger M.; Parkes, James E.

    1991-01-01

    Electric propulsion has applications for orbit raising, maneuvering of large space systems, and interplanetary missions. These missions involve propulsion power levels from tenths to tens of megawatts, depending upon the application. General facility requirements for testing high power electric propulsion at the component and thrust systems level are defined. The characteristics and pumping capabilities of many large vacuum chambers in the United States are reviewed and compared with the requirements for high power electric propulsion testing.

  11. High efficiency solar photovoltaic power module concept

    NASA Technical Reports Server (NTRS)

    Bekey, I.

    1978-01-01

    The investigation of a preliminary concept for high efficiency solar power generation in space is presented. The concept was a synergistic combination of spectral splitting, tailored bandgap cells, high concentration ratios, and cool cell areas.

  12. High power laser perforating tools and systems

    DOEpatents

    Zediker, Mark S; Rinzler, Charles C; Faircloth, Brian O; Koblick, Yeshaya; Moxley, Joel F

    2014-04-22

    ystems devices and methods for the transmission of 1 kW or more of laser energy deep into the earth and for the suppression of associated nonlinear phenomena. Systems, devices and methods for the laser perforation of a borehole in the earth. These systems can deliver high power laser energy down a deep borehole, while maintaining the high power to perforate such boreholes.

  13. Photoconductive switching for high power microwave generation

    SciTech Connect

    Pocha, M.D.; Hofer, W.W.

    1990-10-01

    Photoconductive switching is a technology that is being increasingly applied to generation of high power microwaves. Two primary semiconductors used for these devices are silicon and gallium arsenide. Diamond is a promising future candidate material. This paper discusses the important material parameters and switching modes, critical issues for microwave generation, and future directions for this high power, photoconductive switching technology.

  14. Automated System Tests High-Power MOSFET's

    NASA Technical Reports Server (NTRS)

    Huston, Steven W.; Wendt, Isabel O.

    1994-01-01

    Computer-controlled system tests metal-oxide/semiconductor field-effect transistors (MOSFET's) at high voltages and currents. Measures seven parameters characterizing performance of MOSFET, with view toward obtaining early indication MOSFET defective. Use of test system prior to installation of power MOSFET in high-power circuit saves time and money.

  15. High temperature power electronics for space

    NASA Technical Reports Server (NTRS)

    Hammoud, Ahmad N.; Baumann, Eric D.; Myers, Ira T.; Overton, Eric

    1991-01-01

    A high temperature electronics program at NASA Lewis Research Center focuses on dielectric and insulating materials research, development and testing of high temperature power components, and integration of the developed components and devices into a demonstrable 200 C power system, such as inverter. An overview of the program and a description of the in-house high temperature facilities along with experimental data obtained on high temperature materials are presented.

  16. A high power TWT power processing system. [for communication satellites

    NASA Technical Reports Server (NTRS)

    Farber, B. F.; Goldin, D. S.; Siegert, C.; Gourash, F.

    1974-01-01

    A power processing system (PPS) is designed for a space-type high power (200W RF) multi-collector traveling-wave tube (TWT). The basic power circuit is presented along with the simplified block diagram and the input, output, and general requirements for the PPS design are tabulated. The paper covers the PPS design as to critical TWT/PPS interface requirements, high voltage cathode/collector supply, high voltage components material, packaging, grounding and isolation, and electrical performance. The use of a single two loop control system for the regulation of cathode and collector voltages is shown to give high efficiency, excellent steady-state and transient performance characteristics, and complete protection for TWT and PPS components under transient conditions.

  17. High Density Power Converters for Photovoltaic Power Management

    NASA Astrophysics Data System (ADS)

    Sangwan, Rahul

    In typical photovoltaic systems, PV cells are connected in series to achieve high output voltages, which decreases conduction losses and helps the downstream power electronics operate at higher efficiencies. A series connection means that the current through the string is limited by the worst case cell, substring, or module, which can result in suboptimal operation of the rest of the string. Given how even small shading can have a large effect on performance, there has been growing interest in the use of distributed power management architectures to mitigate losses from variation in PV systems. In particular, partial power processing converters have gained traction as a means to improve the performance of PV arrays with small, distributed converters that configure in parallel with PV cells. These converters can use low voltage components, only process a fraction of the total power allowing them to achieve higher efficiencies and power density and also have higher reliability. This work details the design and operation of a partial power processing converter implemented as a Resonant Switched Capacitor (ReSC) converter. An integrated circuit (IC) is designed in 0.18 mum CMOS process. Operation at high frequencies (20-50 MHz) allows high levels of integration with air core inductors directly attached to the die through a gold bump, solder reflow process. Test results for the IC are presented with power density and efficiency metrics. The IC is then used as a partial power processing converter to implement equalization with a specially constructed PV panel. The converter is shown to mitigate power loss due to mismatch.

  18. The NASA CSTI High Capacity Power Project

    NASA Technical Reports Server (NTRS)

    Winter, J.; Dudenhoefer, J.; Juhasz, A.; Schwarze, G.; Patterson, R.; Ferguson, D.; Schmitz, P.; Vandersande, J.

    1992-01-01

    The elements of the Civilian Space Technology Initiative (CSTI) High Capacity Power Project include Systems Analysis, Stirling Power Conversion, Thermoelectric Power Conversion, Thermal Management, Power Management, Systems Diagnostics, Environmental Interactions, and Material/Structural Development. The overall project will develop and demonstrate the technology base required to provide a wide range of modular power systems compatible with the SP-100 reactor which facilitates operation during lunar and planetary day/night cycles as well as allowing spacecraft operation at any attitude or distance from the sun. Significant accomplishments in all of the project elements are presented, along with revised goals and project timelines recently developed.

  19. 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.

  20. 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

  1. 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. PMID:17431442

  2. High power radial klystron oscillator

    SciTech Connect

    Arman, M.J.

    1995-11-01

    The advantages of the radial klystron amplifier over the conventional klystron amplifier have been reported by Arman et al. Briefly, the radial structure of this design allows for much smaller impedances and thus higher power, the beam-cavity coupling is stronger because the beam travels inside the cavity, and the source is much more compact because there is no need for external magnetic fields. Here the author reports on possible advantages of the radial klystron oscillator over the radial klystron amplifier. The amplifying nature of certain HPM sources is often mandated by the requirement for synchronization and phase-locking of a number of sources in specific applications. In situations where amplification is solely adhered to for the purpose of achieving higher powers, the oscillator will be a better choice if a mechanism can be found to grow the desired mode at the required frequency. By switching to the oscillator mode there will be no need for priming the cavity or maintaining the phase. This simplifies the design and reduces the operational and maintenance cost of the source. Here he reports that an oscillator version of the radial klystron is possible and in fact more suitable for many applications. The mechanism for exciting and growing the mode will be transit-time effects thus providing all the beneficial features of the transit-time oscillators. The complications due to the presence of thin foils in the radial design still persist and will be dealt with in subsequent works. Numerical simulations using the PIC codes MAGIC and SOS indicate the radial klystron oscillator is a viable and efficient means of rf generation.

  3. High-Temperature Passive Power Electronics

    NASA Technical Reports Server (NTRS)

    1997-01-01

    In many future NASA missions - such as deep-space exploration, the National AeroSpace Plane, minisatellites, integrated engine electronics, and ion or arcjet thrusters - high-power electrical components and systems must operate reliably and efficiently in high-temperature environments. The high-temperature power electronics program at the NASA Lewis Research Center focuses on dielectric and insulating material research, the development and characterization of high-temperature components, and the integration of the developed components into a demonstrable 200 C power system - such as an inverter. NASA Lewis has developed high-temperature power components through collaborative efforts with the Air Force Wright Laboratory, Northrop Grumman, and the University of Wisconsin. Ceramic and film capacitors, molypermalloy powder inductors, and a coaxially wound transformer were designed, developed, and evaluated for high-temperature operation.

  4. High power ultrashort pulse lasers

    SciTech Connect

    Perry, M.D.

    1994-10-07

    Small scale terawatt and soon even petawatt (1000 terawatt) class laser systems are made possible by application of the chirped-pulse amplification technique to solid-state lasers combined with the availability of broad bandwidth materials. These lasers make possible a new class of high gradient accelerators based on the large electric fields associated with intense laser-plasma interactions or from the intense laser field directly. Here, we concentrate on the laser technology to produce these intense pulses. Application of the smallest of these systems to the production of high brightness electron sources is also introduced.

  5. High power solid state switches

    NASA Astrophysics Data System (ADS)

    Gundersen, Martin

    1991-11-01

    We have successfully produced an optically triggered thyristor based in Gallium Arsenide, developed a model for breakdown, and are developing two related devices, including a Gallium Arsenide based static inductor thyristor. We are getting at the basic limitations of Gallium Arsenide for these applications, and are developing models for the physical processes that will determine device limitations. The previously supported gas phase work - resulting in the back-lighted thyratron (BLT) - has actually resulted in a very changed view of how switching can be accomplished, and this is impacting the design of important machines. The BLT is being studied internationally: in Japan for laser fusion and laser isotope separation. ITT has built a BLT that has switched 30 kA at 60 kV in testing at NSWC Dahlgren and the device is being commercialized by another American company. Versions of the switch are now being tested for excimer laser and other applications. Basically, the switch, which arose from pulse power physics studies at USC, can switch more current faster (higher di/dt), with less housekeeping, and with other advantageous properties. There are a large number of other new applications, include kinetic energy weapons, pulsed microwave sources and R.F. accelerators.

  6. HIGH AVERAGE POWER OPTICAL FEL AMPLIFIERS.

    SciTech Connect

    BEN-ZVI, ILAN, DAYRAN, D.; LITVINENKO, V.

    2005-08-21

    Historically, the first demonstration of the optical FEL was in an amplifier configuration at Stanford University [l]. There were other notable instances of amplifying a seed laser, such as the LLNL PALADIN amplifier [2] and the BNL ATF High-Gain Harmonic Generation FEL [3]. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance FEL's with average power of 100 kW or more. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting Energy Recovery Linacs (ERL) combine well with the high-gain FEL amplifier to produce unprecedented average power FELs. This combination has a number of advantages. In particular, we show that for a given FEL power, an FEL amplifier can introduce lower energy spread in the beam as compared to a traditional oscillator. This properly gives the ERL based FEL amplifier a great wall-plug to optical power efficiency advantage. The optics for an amplifier is simple and compact. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Linac which is under construction at Brookhaven National Laboratory's Collider-Accelerator Department.

  7. Performance Of The DIII-D ECH High Power Transmission Lines And Launching Systems

    NASA Astrophysics Data System (ADS)

    Cengher, Mirela; Lohr, J.; Gorelov, Y.; Torrezan, A.; Ponce, D.; Moeller, C.; Ellis, R. A.; Kolemen, E.

    2015-11-01

    The Electron Cyclotron Heating (ECH) transmission system on the DIII D tokamak consists of corrugated coaxial 31.75 mm waveguide transmission lines and steerable launching mirrors. Total power injected into plasma can reach up to 3.5 MW, with pulse length up to 5 seconds. The ECH power injected to the tokamak from each gyrotron is measured on a shot-to-shot basis and shows individual average injected powers from a gyrotron into the plasma between 540 and 700 kW. The transmission coefficient including the waveguide line and the MOU is between -1.04 dB and -1.43 dB. The maximum ECH energy injected into DIII-D is 16.6 MJ. The HE11 mode content is over 85 % for all the lines. The four dual waveguide launchers have increased poloidal scanning speed, and can steer the RF beams 40 degrees poloidally in 200 ms, with real-time poloidal motion control by the plasma control system. A new method of in-situ calibration of the mirror angle was used in conjunction with the upgrading of the encoders and motors for the launchers. Work supported by US DOE under DE-FC02-04ER54698 and DE-AC02-09CH11466.

  8. High Power Picosecond Laser Pulse Recirculation

    SciTech Connect

    Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P

    2010-04-12

    We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering based light sources. We demonstrate up to 36x average power enhancement of frequency doubled sub-millijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses.

  9. NASA GRC High Power Electromagnetic Thruster Program

    NASA Technical Reports Server (NTRS)

    LaPointe, Michael R.; Pensil, Eric J.

    2004-01-01

    High-power electromagnetic thrusters have been proposed as primary in-space propulsion options for several bold new interplanetary and deep-space missions. As the lead center for electric propulsion, the NASA Glenn Research Center designs, develops, and tests high-power electromagnetic technologies to meet these demanding mission requirements. Two high-power thruster concepts currently under investigation by Glenn are the magnetoplasmadynamic (MPD) thruster and the Pulsed Inductive Thruster (PIT). This paper describes the MPD thruster and the test facility.

  10. High voltage photovoltaic power converter

    DOEpatents

    Haigh, Ronald E.; Wojtczuk, Steve; Jacobson, Gerard F.; Hagans, Karla G.

    2001-01-01

    An array of independently connected photovoltaic cells on a semi-insulating substrate contains reflective coatings between the cells to enhance efficiency. A uniform, flat top laser beam profile is illuminated upon the array to produce electrical current having high voltage. An essentially wireless system includes a laser energy source being fed through optic fiber and cast upon the photovoltaic cell array to prevent stray electrical signals prior to use of the current from the array. Direct bandgap, single crystal semiconductor materials, such as GaAs, are commonly used in the array. Useful applications of the system include locations where high voltages are provided to confined spaces such as in explosive detonation, accelerators, photo cathodes and medical appliances.

  11. High Power Co-Axial Coupler

    SciTech Connect

    Neubauer, M.; Dudas, A.; Rimmer, Robert A.; Guo, Jiquan; Williams, R. Scott

    2013-12-01

    A very high power Coax RF Coupler (MW-Level) is very desirable for a number of accelerator and commercial applications. For example, the development of such a coupler operating at 1.5 GHz may permit the construction of a higher-luminosity version of the Electron-Ion Collider (EIC) being planned at JLab. Muons, Inc. is currently funded by a DOE STTR grant to develop a 1.5-GHz high-power doublewindowcoax coupler with JLab (about 150 kW). Excellent progress has been made on this R&D project, so we propose an extension of this development to build a very high power coax coupler (MW level peak power and a max duty factor of about 4%). The dimensions of the current coax coupler will be scaled up to provide higher power capability.

  12. High-efficiency solid state power amplifier

    NASA Technical Reports Server (NTRS)

    Wallis, Robert E. (Inventor); Cheng, Sheng (Inventor)

    2005-01-01

    A high-efficiency solid state power amplifier (SSPA) for specific use in a spacecraft is provided. The SSPA has a mass of less than 850 g and includes two different X-band power amplifier sections, i.e., a lumped power amplifier with a single 11-W output and a distributed power amplifier with eight 2.75-W outputs. These two amplifier sections provide output power that is scalable from 11 to 15 watts without major design changes. Five different hybrid microcircuits, including high-efficiency Heterostructure Field Effect Transistor (HFET) amplifiers and Monolithic Microwave Integrated Circuit (MMIC) phase shifters have been developed for use within the SSPA. A highly efficient packaging approach enables the integration of a large number of hybrid circuits into the SSPA.

  13. High-power red VCSEL arrays

    NASA Astrophysics Data System (ADS)

    Seurin, Jean-Francois; Khalfin, Viktor; Xu, Guoyang; Miglo, Alexander; Li, Daizong; Zhou, Delai; Sundaresh, Mukta; Zou, Wei-Xiong; Lu, Chien-Yao; Wynn, James D.; Ghosh, Chuni

    2013-03-01

    High-power red laser sources are used in many applications such as cosmetics, cancer photodynamic therapy, and DNA sequencing in the medical field, laser-based RGB projection display, and bar-code scanning to name a few. Verticalcavity surface-emitting lasers (VCSELs) can be used as high-power laser sources, as efficient single devices can be configured into high-power two-dimensional arrays and scaled into modules of arrays. VCSELs emit in a circular, uniform beam which can greatly reduce the complexity and cost of optics. Other advantages include a narrow and stable emission spectrum, low speckle of the far-field emission, and good reliability. However, developing efficient red VCSEL sources presents some challenges because of the reduced quantum-well carrier confinement and the increased Aluminum content (to avoid absorption) which increases thermal impedance, and also decreases the DBR index contrast resulting in increased penetration length and cavity losses. We have recently developed VCSEL devices lasing in the visible 6xx nm wavelength band, and reaching 30% power conversion efficiency. We fabricated high-power 2D arrays by removing the GaAs substrate entirely and soldered the chips on high thermal conductivity submounts. Such arrays have demonstrated several Watts of output power at room temperature, in continuous-wave (CW) operation. Several tens of Watts are obtained in QCW operation. Results and challenges of these high-power visible VCSEL arrays will be discussed.

  14. Dynamic nuclear polarization by frequency modulation of a tunable gyrotron of 260 GHz

    NASA Astrophysics Data System (ADS)

    Yoon, Dongyoung; Soundararajan, Murari; Cuanillon, Philippe; Braunmueller, Falk; Alberti, Stefano; Ansermet, Jean-Philippe

    2016-01-01

    An increase in Dynamic Nuclear Polarization (DNP) signal intensity is obtained with a tunable gyrotron producing frequency modulation around 260 GHz at power levels less than 1 W. The sweep rate of frequency modulation can reach 14 kHz, and its amplitude is fixed at 50 MHz. In water/glycerol glassy ice doped with 40 mM TEMPOL, the relative increase in the DNP enhancement was obtained as a function of frequency-sweep rate for several temperatures. A 68 % increase was obtained at 15 K, thus giving a DNP enhancement of about 80. By employing λ / 4 and λ / 8 polarizer mirrors, we transformed the polarization of the microwave beam from linear to circular, and achieved an increase in the enhancement by a factor of about 66% for a given power.

  15. 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.

  16. Dynamic nuclear polarization by frequency modulation of a tunable gyrotron of 260GHz.

    PubMed

    Yoon, Dongyoung; Soundararajan, Murari; Cuanillon, Philippe; Braunmueller, Falk; Alberti, Stefano; Ansermet, Jean-Philippe

    2016-01-01

    An increase in Dynamic Nuclear Polarization (DNP) signal intensity is obtained with a tunable gyrotron producing frequency modulation around 260GHz at power levels less than 1W. The sweep rate of frequency modulation can reach 14kHz, and its amplitude is fixed at 50MHz. In water/glycerol glassy ice doped with 40mM TEMPOL, the relative increase in the DNP enhancement was obtained as a function of frequency-sweep rate for several temperatures. A 68 % increase was obtained at 15K, thus giving a DNP enhancement of about 80. By employing λ/4 and λ/8 polarizer mirrors, we transformed the polarization of the microwave beam from linear to circular, and achieved an increase in the enhancement by a factor of about 66% for a given power. PMID:26759116

  17. High Power Amplifier Harmonic Output Level Measurement

    NASA Technical Reports Server (NTRS)

    Perez, R. M.; Hoppe, D. J.; Khan, A. R.

    1995-01-01

    A method is presented for the measurement of the harmonic output power of high power klystron amplifiers, involving coherent hemispherical radiation pattern measurements of the radiated klystron output. Results are discussed for the operation in saturated and unsaturated conditions, and with a waveguide harmonic filter included.

  18. High-power VCSEL systems and applications

    NASA Astrophysics Data System (ADS)

    Moench, Holger; Conrads, Ralf; Deppe, Carsten; Derra, Guenther; Gronenborn, Stephan; Gu, Xi; Heusler, Gero; Kolb, Johanna; Miller, Michael; Pekarski, Pavel; Pollmann-Retsch, Jens; Pruijmboom, Armand; Weichmann, Ulrich

    2015-03-01

    Easy system design, compactness and a uniform power distribution define the basic advantages of high power VCSEL systems. Full addressability in space and time add new dimensions for optimization and enable "digital photonic production". Many thermal processes benefit from the improved control i.e. heat is applied exactly where and when it is needed. The compact VCSEL systems can be integrated into most manufacturing equipment, replacing batch processes using large furnaces and reducing energy consumption. This paper will present how recent technological development of high power VCSEL systems will extend efficiency and flexibility of thermal processes and replace not only laser systems, lamps and furnaces but enable new ways of production. High power VCSEL systems are made from many VCSEL chips, each comprising thousands of low power VCSELs. Systems scalable in power from watts to multiple ten kilowatts and with various form factors utilize a common modular building block concept. Designs for reliable high power VCSEL arrays and systems can be developed and tested on each building block level and benefit from the low power density and excellent reliability of the VCSELs. Furthermore advanced assembly concepts aim to reduce the number of individual processes and components and make the whole system even more simple and reliable.

  19. Driver Circuit For High-Power MOSFET's

    NASA Technical Reports Server (NTRS)

    Letzer, Kevin A.

    1991-01-01

    Driver circuit generates rapid-voltage-transition pulses needed to switch high-power metal oxide/semiconductor field-effect transistor (MOSFET) modules rapidly between full "on" and full "off". Rapid switching reduces time of overlap between appreciable current through and appreciable voltage across such modules, thereby increasing power efficiency.

  20. Test results of high-voltage, high-power, solid-state remote power controllers

    NASA Technical Reports Server (NTRS)

    Johnson, Yvette Binford; Kapustka, Robert E.

    1988-01-01

    This report discusses the results of testing high-voltage, high-power, solid-state remote power controllers (RPC) using RPCs designed and built by John C. Sturman at the Lewis Research Center, Cleveland, Ohio, and utilizing the Autonomously Managed Power Systems (AMPS) breadboard/test facility. These test results are used to determine usefulness of the RPCs for future applications in high-voltage direct-current space power.

  1. High-Speed, high-power, switching transistor

    NASA Technical Reports Server (NTRS)

    Carnahan, D.; Ohu, C. K.; Hower, P. L.

    1979-01-01

    Silicon transistor rate for 200 angstroms at 400 to 600 volts combines switching speed of transistors with ruggedness, power capacity of thyristor. Transistor introduces unique combination of increased power-handling capability, unusally low saturation and switching losses, and submicrosecond switching speeds. Potential applications include high power switching regulators, linear amplifiers, chopper controls for high frequency electrical vehicle drives, VLF transmitters, RF induction heaters, kitchen cooking ranges, and electronic scalpels for medical surgery.

  2. ECH control system for new 1 MW 110 GHz gyrotrons at DIII-D

    SciTech Connect

    Wright, A.L.; Tooker, J.; Allen, J.C.; Cary, W.P.; Harris, T.E.

    1995-10-01

    Two new Varian 1 MW 110 GHz gyrotrons are currently being developed and are due to be tested at General Atomics next year. A new cost-effective gyrotron control system to operate multiple gyrotrons simultaneously is being developed. Different systems and combinations that were considered include CAMAC, PLC, VXIbus, and a local computer. This paper will explain the decision making processes used in choosing and implementing the new control system architecture.

  3. 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.

  4. Coupling output of multichannel high power microwaves

    SciTech Connect

    Li Guolin; Shu Ting; Yuan Chengwei; Zhang Jun; Yang Jianhua; Jin Zhenxing; Yin Yi; Wu Dapeng; Zhu Jun; Ren Heming; Yang Jie

    2010-12-15

    The coupling output of multichannel high power microwaves is a promising technique for the development of high power microwave technologies, as it can enhance the output capacities of presently studied devices. According to the investigations on the spatial filtering method and waveguide filtering method, the hybrid filtering method is proposed for the coupling output of multichannel high power microwaves. As an example, a specific structure is designed for the coupling output of S/X/X band three-channel high power microwaves and investigated with the hybrid filtering method. In the experiments, a pulse of 4 GW X band beat waves and a pulse of 1.8 GW S band microwave are obtained.

  5. High power density carbonate fuel cell

    SciTech Connect

    Yuh, C.; Johnsen, R.; Doyon, J.; Allen, J.

    1996-12-31

    Carbonate fuel cell is a highly efficient and environmentally clean source of power generation. Many organizations worldwide are actively pursuing the development of the technology. Field demonstration of multi-MW size power plant has been initiated in 1996, a step toward commercialization before the turn of the century, Energy Research Corporation (ERC) is planning to introduce a 2.85MW commercial fuel cell power plant with an efficiency of 58%, which is quite attractive for distributed power generation. However, to further expand competitive edge over alternative systems and to achieve wider market penetration, ERC is exploring advanced carbonate fuel cells having significantly higher power densities. A more compact power plant would also stimulate interest in new markets such as ships and submarines where space limitations exist. The activities focused on reducing cell polarization and internal resistance as well as on advanced thin cell components.

  6. Very high power THz radiation sources

    SciTech Connect

    Carr, G.L.; Martin, Michael C.; McKinney, Wayne R.; Jordan, K.; Neil, George R.; Williams, G.P.

    2002-10-31

    We report the production of high power (20 watts average, {approx} 1 Megawatt peak) broadband THz light based on coherent emission from relativistic electrons. Such sources are ideal for imaging, for high power damage studies and for studies of non-linear phenomena in this spectral range. We describe the source, presenting theoretical calculations and their experimental verification. For clarity we compare this source to one based on ultrafast laser techniques.

  7. Spacecraft high-voltage power supply construction

    NASA Technical Reports Server (NTRS)

    Sutton, J. F.; Stern, J. E.

    1975-01-01

    The design techniques, circuit components, fabrication techniques, and past experience used in successful high-voltage power supplies for spacecraft flight systems are described. A discussion of the basic physics of electrical discharges in gases is included and a design rationale for the prevention of electrical discharges is provided. Also included are typical examples of proven spacecraft high-voltage power supplies with typical specifications for design, fabrication, and testing.

  8. High power regenerative laser amplifier

    DOEpatents

    Miller, J.L.; Hackel, L.A.; Dane, C.B.; Zapata, L.E.

    1994-02-08

    A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse. 7 figures.

  9. High power regenerative laser amplifier

    DOEpatents

    Miller, John L.; Hackel, Lloyd A.; Dane, Clifford B.; Zapata, Luis E.

    1994-01-01

    A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse.

  10. High Voltage Power Transmission for Wind Energy

    NASA Astrophysics Data System (ADS)

    Kim, Young il

    The high wind speeds and wide available area at sea have recently increased the interests on offshore wind farms in the U.S.A. As offshore wind farms become larger and are placed further from the shore, the power transmission to the onshore grid becomes a key feature. Power transmission of the offshore wind farm, in which good wind conditions and a larger installation area than an onshore site are available, requires the use of submarine cable systems. Therefore, an underground power cable system requires unique design and installation challenges not found in the overhead power cable environment. This paper presents analysis about the benefit and drawbacks of three different transmission solutions: HVAC, LCC/VSC HVDC in the grid connecting offshore wind farms and also analyzed the electrical characteristics of underground cables. In particular, loss of HV (High Voltage) subsea power of the transmission cables was evaluated by the Brakelmann's theory, taking into account the distributions of current and temperature.

  11. Inverter design for high frequency power distribution

    NASA Technical Reports Server (NTRS)

    King, R. J.

    1985-01-01

    A class of simple resonantly commutated inverters are investigated for use in a high power (100 KW - 1000 KW) high frequency (10 KHz - 20 KHz) AC power distribution system. The Mapham inverter is found to provide a unique combination of large thyristor turn-off angle and good utilization factor, much better than an alternate 'current-fed' inverter. The effects of loading the Mapham inverter entirely with rectifier loads are investigated by simulation and with an experimental 3 KW 20 KHz inverter. This inverter is found to be well suited to a power system with heavy rectifier loading.

  12. Optical power splitter for splitting high power light

    DOEpatents

    English, Jr., Ronald E.; Christensen, John J.

    1995-01-01

    An optical power splitter for the distribution of high-power light energy has a plurality of prisms arranged about a central axis to form a central channel. The input faces of the prisms are in a common plane which is substantially perpendicular to the central axis. A beam of light which is substantially coaxial to the central axis is incident on the prisms and at least partially strikes a surface area of each prism input face. The incident beam also partially passes through the central channel.

  13. Optical power splitter for splitting high power light

    DOEpatents

    English, R.E. Jr.; Christensen, J.J.

    1995-04-18

    An optical power splitter for the distribution of high-power light energy has a plurality of prisms arranged about a central axis to form a central channel. The input faces of the prisms are in a common plane which is substantially perpendicular to the central axis. A beam of light which is substantially coaxial to the central axis is incident on the prisms and at least partially strikes a surface area of each prism input face. The incident beam also partially passes through the central channel. 5 figs.

  14. Stability analysis of a coaxial-waveguide gyrotron traveling-wave amplifier

    SciTech Connect

    Hung, C.L.; Yeh, Y.S.

    2005-10-01

    The gyrotron traveling-wave tube (gyro-TWT) amplifier is known to be highly susceptible to spurious oscillations. This study develops a simulation approach to analyze the stability of a coaxial-waveguide gyro-TWT with distributed wall losses. The interplay among the absolute instabilities, the gyrotron backward-wave oscillations, and the circuit parameters is analyzed. Simulation results reveal that the distributed wall losses effectively stabilize spurious oscillations in the coaxial gyro-TWT. Furthermore, the wall resistivity of the center conductor is shown to be an additional effective mechanism for suppressing oscillations. Under stable operation conditions, the coaxial gyro-TWT with distributed losses is predicted to generate 435 kW in the Ka band with 31% efficiency, a saturated gain of 45 dB, and a bandwidth of 1.86 GHz ({approx_equal}5.8%) for a 70 kV, 20 A electron beam with an {alpha}(={nu}{sub perpendicular})/{nu}{sub z})=1.0 and an axial velocity spread of {delta}{nu}{sub z}/{nu}{sub z}=5%.

  15. Plasma structures observed in gas breakdown using a 1.5 MW, 110 GHz pulsed gyrotron

    SciTech Connect

    Hidaka, Yoshiteru; Choi, E. M.; Mastovsky, I.; Shapiro, M. A.; Sirigiri, J. R.; Temkin, R. J.; Edmiston, G. F.; Neuber, A. A.; Oda, Y.

    2009-05-15

    Regular two-dimensional plasma filamentary arrays have been observed in gas breakdown experiments using a pulsed 1.5 MW, 110 GHz gyrotron. The gyrotron Gaussian output beam is focused to an intensity of up to 4 MW/cm{sup 2}. The plasma filaments develop in an array with a spacing of about one quarter wavelength, elongated in the electric field direction. The array was imaged using photodiodes, a slow camera, which captures the entire breakdown event, and a fast camera with a 6 ns window. These diagnostics demonstrate the sequential development of the array propagating back toward the source. Gases studied included air, nitrogen, SF{sub 6}, and helium at various pressures. A discrete plasma array structure is observed at high pressure, while a diffuse plasma is observed at lower pressure. The propagation speed of the ionization front for air and nitrogen at atmospheric pressure for 3 MW/cm{sup 2} was found to be of the order of 10 km/s.

  16. 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.

  17. High Power Particle Beams and Pulsed Power for Industrial Applications

    NASA Astrophysics Data System (ADS)

    Bluhm, Hansjoachim; An, Wladimir; Engelko, Wladimir; Giese, Harald; Frey, Wolfgang; Heinzel, Annette; Hoppé, Peter; Mueller, Georg; Schultheiss, Christoph; Singer, Josef; Strässner, Ralf; Strauß, Dirk; Weisenburger, Alfons; Zimmermann, Fritz

    2002-12-01

    Several industrial scale projects with economic and ecologic potential are presently emanating from research and development in the fields of high power particle beams and pulsed power in Europe. Material surface modifications with large area pulsed electron beams are used to protect high temperature gas turbine blades and steel structures in Pb/Bi cooled accelerator driven nuclear reactor systems against oxidation and corrosion respectively. Channel spark electron beams are applied to deposit bio-compatible or bio-active layers on medical implants. Cell membranes are perforated with strong pulsed electric fields to extract nutritive substances or raw materials from the cells and to kill bacteria for sterilization of liquids. Eletrodynamic fragmentation devices are developed to reutilize concrete aggregates for the production of high quality secondary concrete. All activities have a large potential to contribute to a more sustainable economy.

  18. High power impulse magnetron sputtering discharge

    SciTech Connect

    Gudmundsson, J. T.; Brenning, N.; Lundin, D.; Helmersson, U.

    2012-05-15

    The high power impulse magnetron sputtering (HiPIMS) discharge is a recent addition to plasma based sputtering technology. In HiPIMS, high power is applied to the magnetron target in unipolar pulses at low duty cycle and low repetition frequency while keeping the average power about 2 orders of magnitude lower than the peak power. This results in a high plasma density, and high ionization fraction of the sputtered vapor, which allows better control of the film growth by controlling the energy and direction of the deposition species. This is a significant advantage over conventional dc magnetron sputtering where the sputtered vapor consists mainly of neutral species. The HiPIMS discharge is now an established ionized physical vapor deposition technique, which is easily scalable and has been successfully introduced into various industrial applications. The authors give an overview of the development of the HiPIMS discharge, and the underlying mechanisms that dictate the discharge properties. First, an introduction to the magnetron sputtering discharge and its various configurations and modifications is given. Then the development and properties of the high power pulsed power supply are discussed, followed by an overview of the measured plasma parameters in the HiPIMS discharge, the electron energy and density, the ion energy, ion flux and plasma composition, and a discussion on the deposition rate. Finally, some of the models that have been developed to gain understanding of the discharge processes are reviewed, including the phenomenological material pathway model, and the ionization region model.

  19. High-Power, High-Temperature Superconductor Technology Development

    NASA Technical Reports Server (NTRS)

    Bhasin, Kul B.

    2005-01-01

    Since the first discovery of high-temperature superconductors (HTS) 10 years ago, the most promising areas for their applications in microwave systems have been as passive components for communication systems. Soon after the discovery, experiments showed that passive microwave circuits made from HTS material exceeded the performance of conventional devices for low-power applications and could be 10 times as small or smaller. However, for superconducting microwave components, high-power microwave applications have remained elusive until now. In 1996, DuPont and Com Dev Ltd. developed high-power superconducting materials and components for communication applications under a NASA Lewis Research Center cooperative agreement, NCC3-344 "High Power High Temperature Superconductor (HTS) Technology Development." The agreement was cost shared between the Defense Advanced Research Projects Agency's (DARPA) Technology Reinvestment Program Office and the two industrial partners. It has the following objectives: 1) Material development and characterization for high-power HTS applications; 2) Development and validation of generic high-power microwave components; 3) Development of a proof-of-concept model for a high-power six-channel HTS output multiplexer.

  20. The NASA CSTI High Capacity Power Project

    SciTech Connect

    Winter, J.; Dudenhoefer, J.; Juhasz, A.; Schwarze, G.; Patterson, R.; Ferguson, D.; Titran, R.; Schmitz, P.; Vandersande, J.

    1994-09-01

    The SP-100 Space Nuclear Power Program was established in 1983 by DOD, DOE, and NASA as a joint program to develop technology for military and civil applications. Starting in 1986, NASA has funded a technology program to maintain the momentum of promising aerospace technology advancement started during Phase I of SP-100 and to strengthen, in key areas, the changes for successful development and growth capability of space nuclear reactor power systems for a wide range of future space applications. The elements of the CSTI High Capacity Power Project include Systems Analysis, Stirling Power Conversion, Thermoelectric Power Conversion, Thermal Management, Power Management, Systems Diagnostics, Environmental Interactions, and Material/Structural Development. Technology advancement in all elements is required to provide the growth capability, high reliability and 7 to 10 year lifetime demanded for future space nuclear power systems. The overall project with develop and demonstrate the technology base required to provide a wide range of modular power systems compatible with the SP-100 reactor which facilitates operation during lunar and planetary day/night cycles as well as allowing spacecraft operation at any attitude or distance from the sun. Significant accomplishments in all of the project elements will be presented, along with revised goals and project timelines recently developed.