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Microwave transport system for the MTX (Microwave Tokamak Experiment)

Description: This paper presents the design and construction, as well as the initial operation, of the Microwave Transmission System. The system consists of containment vessels, mirror boxes, mirrors, an alignment system, two turbo-molecular pump vacuum stations, and microwave source. Fifty-ns-length pulses of 6-MeV electrons pass through a free electron laser (FEL) wiggler. A 300 W extended interaction oscillator (EIO) of 140 GHz frequency supplies the seed signal for amplification in the wiggler. The electron beam is dumped and the microwave beam is transmitted quasi-optically 90 ft by six aluminum mirrors through an evacuated tube. Three of the mirrors are elliptical paraboloids and the others are flat. A seventh mirror is rotated into the microwave beam to divert it into a load tank. The transport vacuum vessel is 20-in.-diameter stainless steel tube with bellows and mirror boxes at each mirror. Two vacuum systems at each end of the transport tube allow a base pressure of 10{sup {minus}7} Torr to be attained by 7000 L/s of turbo-molecular pumping. Also at each mirror, at the MTX vessel, and at the two ends of the wiggler waveguide are HeNe laser detectors used for vacuum alignment. Descriptions of the major components, their requirements and system requirements will be presented, and the initial operation of the system and its performance will be described. 7 figs., 2 tabs.
Date: September 27, 1989
Creator: Felker, B. & Ferguson, S.W.
Partner: UNT Libraries Government Documents Department

Ion cyclotron resonant heating 2 x 170/sup 0/ loop antenna for the Tandem Mirror Experiment-Upgrade

Description: This paper reviews the mechanical design and improvements that have taken place on the loop type ion cyclotron resonance heating (ICRH) antennas that are located in the center cell region of the Tandem Mirror Experiment-Upgrade (TMX-U).
Date: November 14, 1985
Creator: Brooksby, C.A.; Ferguson, S.W.; Molvik, A.W. & Barter, J.
Partner: UNT Libraries Government Documents Department

Ion Cyclotron Resonant Heating slot antenna for the Tandem Mirror Experiment-Upgrade

Description: The Ion Cyclotron Resonant Heating (ICRH) slot antenna has been a part of the ion and electron plasma heating system in the central cell region of the Tandem Mirror Experiment-Upgrade (TMX-U). This paper presents the mechanical design and arrangement of the antenna, coax feed lines, feedthroughs, and matching network for the slot antenna.
Date: November 14, 1985
Creator: Brooksby, C.A.; Calderson, M.O.; Cummins, W.F.; Ferguson, S.W. & Williamson, V.L.
Partner: UNT Libraries Government Documents Department

Mean time between failures (MTBF) and availability of the Gyrotron system used on the Microwave Tokamak Experiment at Lawrence Livermore National Laboratory

Description: This paper presents an analysis of the mean time between failures (MTBF) and availability history of the Varian VGT8140, 400 Watt, 140 GHz Gyrotron that was operated on the Microwave Tokamak Experiment (MTX) at the Lawrence Livermore National Laboratory (LLNL).
Date: September 3, 1993
Creator: Ferguson, S. W.; Jackson, M. C. & Seilhymer, D. B.
Partner: UNT Libraries Government Documents Department

Impedance-power effects on plasma polymer surface finish using a helical resonator discharge

Description: Plasma polymerized organic coatings are used in the fabrication of targets for experiments in the Inertial Confinement Fusion (ICF) program at Lawrence Livermore National Laboratory. The authors are performing experiments to understand the process conditions leading to the preparation of smooth ({approx}100{Angstrom}) plasma polymer surfaces while maintaining the highest deposition rate possible. It had been reported by Howling et al., that the formation of particulate matter in the deposition of silicon by the plasma reaction of silane affected the plasma impedance. This suggested that experiments designed to examine the correlation of surface texture with plasma impedance would be of interest. Furthermore, it is possible that an impedance change may cause a change in the power coupling efficiency from the transmitter to the plasma. Preliminary work in the authors laboratory indicated that the reactor temperature influenced the surface texture. The focus of this paper is to carefully examine the effects of reactor temperature on the surface texture of the plasma polymer, ensuring constant reactor conditions especially with respect to rf power.
Date: December 9, 1992
Creator: Brusasco, R.; Ferguson, S. W. & Stever, R.
Partner: UNT Libraries Government Documents Department

ICRF heating of passing ions in TMX-U

Description: By placing ion-cyclotron resonant frequency (ICRF) antennas on both sides of a midplane gas-feed system in the central cell of the Tandem Mirror Experiment-Upgrade (TMX-U), our results have improved in the following areas: (a) The end losses out both ends show a factor of 3 to 4 increase in passing-ion temperatures and a factor of 2 to 3 decrease in passing-ion densities. (b) The passing-ion heating is consistent with Monte Carlo predictions. (c) The plasma density can be sustained by ICRF plus gas fueling as observed on other experiments.
Date: April 1, 1986
Creator: Molvik, A.W.; Dimonte, G.; Barter, J.; Campbell, R.; Cummins, W.F.; Falabella, S. et al.
Partner: UNT Libraries Government Documents Department

MTX/ELF II (Microwave Tokamak Experiment/ Electron Laser Facility II) microwave power measurements and calibration for the 2-GW, 140-GHZ, ELF II free-electron laser (FEL)

Description: We have developed techniques for measuring the power and frequency of the Electron Laser Facility (ELF) II free-electron laser (FEL) used for plasma heating experiments on the Microwave Tokamak Experiment (MTX). We also have designed a multichannel, 140-GHz receiver capable of measuring FEL power levels from 10 mW to 0.1 {mu}W within an accuracy of {plus minus}1 dB with a 50-dB dynamic range and a 2-ns response time. By using calibrated attenuators, we can measure power levels from 10 GW to 0.1 {mu}W. We sample the microwave output of the FEL in a microwave load tank by using WR-8 or WR-28 stub waveguide antennas. Microwave turning mirrors are used to guide the microwave beam down an evacuated beam tube to the MTX. Stub, WR-8, fundamental-mode, waveguide antennas are used for beam detection on the microwave turning mirrors. Orthogonal, WR-8, stub waveguides are machined into the surfaces of the mirrors and used as directional couplers to measure forward and reflected power from the FEL. The microwave power is then transported to the microwave receiver via a low-loss, over-moded, WR-28 waveguide. A movable modes probe in the microwave load tank is used to scan across the microwave beam to determine the modes content of the beam. Frequency stability of the FEL is measured with a fast, frequency-modulation detector (FFMD) capable of measuring frequency shifts and modulation on a 2- to 4-ns time frame. 2 refs., 14 figs.
Date: September 27, 1989
Creator: Ferguson, S.W.; Stever, R.; Throop, A.; Felker, B. & Franklin, R.
Partner: UNT Libraries Government Documents Department

RF power diagnostics and control on the DIII-D, 4 MW 30--120 MHz fast wave current drive system (FWCD)

Description: The Fast Wave Current Drive System uses three 2 MW transmitters to drive three antennas inside the DIII-D vacuum vessel. This paper describes the diagnostics for this system. The diagnostics associated with the General Atomics Fast Wave Current Drive System allow the system tuning to be analyzed and modified on a between shot basis. The transmitters can be exactly tuned to match the plasma with only one tuning shot into the plasma. This facilitates maximum rf power utilization.
Date: October 1, 1995
Creator: Ferguson, S.W.; Allen, J.C.; Callis, R.W.; Cary, W.P. & Harris, T.E.
Partner: UNT Libraries Government Documents Department

RF high voltage performance of RF transmission line components on the DIII-D Fast Wave Current Drive (FWCD) System

Description: The performance of the high voltage rf components of the DIII-D Fast Wave Current Drive System (FWCD) have been evaluated under various conditions of insulator configuration, insulator material, insulating gas and gas pressure. The insulator materials that have been investigated are alumina, steatite, pyrex, quartz, and teflon. The results of this evaluation are discussed in this paper. Additionally a rf high potter was developed to aid in the evaluation of rf high voltage components. The high potter consists of a 50 {Omega}, 1/4 wavelength cavity with a variable position short and a 50 ohm matched tap at one end of the cavity. With this configuration rf voltages were generated in excess of 100 kVp in the frequency range 30 to 60 MHz.
Date: December 1, 1995
Creator: Ferguson, S.W.; Callis, R.W.; Cary, W.P.; Phelps, D.A.; Ponce, D.; Baity, F.W. et al.
Partner: UNT Libraries Government Documents Department

Ion Cyclotron Resonant Heating (ICRH) system used on the Tandem Mirror Experiment-Upgrade (TMX-U)

Description: Ion Cyclotron Resonant Heating (ICRH) is part of the plasma heating system used on the TMX-U experiment. Radio frequency (RF) energy is injected into the TMX-U plasma at a frequency near the fundamental ion resonance (2 to 5 MHz). The RF fields impart high velocities to the ions in a direction perpendicular to the TMX-U magnetic field. Particle collision then converts this perpendicular heating to uniform plasma heating. This paper describes the various aspects of the ICRH system: antennas, power supplies, computer control, and data acquisition. 4 refs., 10 figs.
Date: November 11, 1985
Creator: Ferguson, S.W.; Maxwell, T.M.; Antelman, D.R.; Scofield, D.W.; Brooksby, C.A.; Karsner, P.G. et al.
Partner: UNT Libraries Government Documents Department

Analysis and experiments of a whistler-wave plasma thruster

Description: A plasma thruster operating at high specific impulse ({ge} 3500 s) has been proposed to be based on electron-cyclotron resonance heating of whistler waves propagating on a plasma column on a magnetic hill. Calculations using a particle-in-cell code demonstrate that the distortion of the electron velocity distribution by the heating significantly reduces the flow of plasma up the field, greatly improving efficiency and reducing material interactions relative to a thermal plasma. These and other calculations are presented together with initial experiments on the plasma generated in the proposed device. The experiments are conducted in a magnetic field (3.3 {times} 10{sup {minus}2} T at resonance) and a magnetic mirror ratio of 5. Microwaves (0.915 GHz, <20 kW) are coupled to the plasma with a helical antenna. Vacuum field measurements are in good agreement with prediction. The desired plasma spatial distribution has not yet been achieved.
Date: August 6, 1993
Creator: Hooper, E. B.; Ferguson, S. W.; Makowski, M. A.; Stallard, B. W. & Power, J. L.
Partner: UNT Libraries Government Documents Department

4 MW upgrade to DIII-D FWCD system: System commissioning and initial operation

Description: The initial installation of the 4 MW fast wave current drive (FWCD) upgrade started in 1992 with the purchase of two ABB/Thomcast AG rf power amplifiers. These amplifiers cover the frequency range 30 MHz to 120 MHz. A maximum output power of over 2 MW between 30 MHz and 80 MHz and 1 MW at 120 MHz were the specification requirements. The system as installed is comprised of the two mentioned rf amplifiers, coaxial transmission and matching components, rf phase and amplitude monitoring, and a SUN SparcStation 10 control system. Due to various reasons almost every major component in the system required redesign and engineering in order to meet the system requirements. The failures, probable cause and the final redesigns will be discussed as well as some thoughts on how better to specify system requirements for future systems.
Date: October 1995
Creator: Cary, W. P.; Callis, R. W.; de Grassie, J. S.; Harris, T. E.; O`Neill, R. C.; Pinsker, R. I. et al.
Partner: UNT Libraries Government Documents Department

Lawrence Livermore National Laboratory DIII-D cooperation: 1987 annual report

Description: This report summarizes the Lawrence Livermore National Laboratory (LLNL) DIII-D cooperation during FY87. The LLNL participation in DIII-D concentrated on three principal areas: ECH and current-drive physics, divertor and edge physics, and tokamak operations. These topics are dicussed in this report. 27 refs., 11 figs.
Date: February 24, 1988
Creator: Allen, S.L.; Calderon, M.O.; Ellis, R.M.; Evans, J.C.; Ferguson, S.W.; Hill, D.N. et al.
Partner: UNT Libraries Government Documents Department

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

Description: 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.
Date: August 9, 1990
Creator: Stallard, B.W.; Turner, W.C.; Allen, S.L.; Byers, J.A.; Felker, B.; Fenstermacher, M.E. et al.
Partner: UNT Libraries Government Documents Department

Status of the National Ignition Facility Integrated Computer Control System (ICCS) on the Path to Ignition

Description: The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a stadium-sized facility under construction that will contain a 192-beam, 1.8-Megajoule, 500-Terawatt, ultraviolet laser system together with a 10-meter diameter target chamber with room for multiple experimental diagnostics. NIF is the world's largest and most energetic laser experimental system, providing a scientific center to study inertial confinement fusion (ICF) and matter at extreme energy densities and pressures. NIF's laser beams are designed to compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. NIF is comprised of 24 independent bundles of 8 beams each using laser hardware that is modularized into more than 6,000 line replaceable units such as optical assemblies, laser amplifiers, and multifunction sensor packages containing 60,000 control and diagnostic points. NIF is operated by the large-scale Integrated Computer Control System (ICCS) in an architecture partitioned by bundle and distributed among over 800 front-end processors and 50 supervisory servers. NIF's automated control subsystems are built from a common object-oriented software framework based on CORBA distribution that deploys the software across the computer network and achieves interoperation between different languages and target architectures. A shot automation framework has been deployed during the past year to orchestrate and automate shots performed at the NIF using the ICCS. In December 2006, a full cluster of 48 beams of NIF was fired simultaneously, demonstrating that the independent bundle control system will scale to full scale of 192 beams. At present, 72 beams have been commissioned and have demonstrated 1.4-Megajoule capability of infrared light. During the next two years, the control system will be expanded to include automation of target area systems including final optics, target positioners and diagnostics, in preparation for project completion in 2009. Additional capabilities to support fusion ignition ...
Date: September 11, 2007
Creator: Lagin, L. J.; Bettenhauasen, R. C.; Bowers, G. A.; Carey, R. W.; Edwards, O. D.; Estes, C. M. et al.
Partner: UNT Libraries Government Documents Department