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High power, high frequency, vacuum flange

Description: This invention is comprised of 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.
Date: December 31, 1991
Creator: Felker, B. & McDaniel, M.
Partner: UNT Libraries Government Documents Department

The cryogenic helium cooling system for the Tokamak physics experiment

Description: The Tokamak Physics Experiment (TPX) will use supercritical helium to cool all the magnets and supply helium to the Vacuum cryopumping subsystem. The heat loads will come from the standard steady state conduction and thermal radiation sources and from the pulsed loads of the nuclear and eddy currents caused by the Central Solenoid Coils and the plasma positioning coils. The operations of the TPX will begin with pulses of up to 1000 seconds in duration every 75 minutes. The helium system utilizes a pulse load leveling scheme to buffer out the effects of the pulse load and maintain a constant cryogenic plant operation. The pulse load leveling scheme utilizes the thermal mass of liquid and gaseous helium stored in a remote dewar to absorb the pulses of the tokamak loads. The mass of the stored helium will buffer out the temperature pulses allowing 5 K helium to be delivered to the magnets throughout the length of the pulse. The temperature of the dewar will remain below 5 K with all the energy of the pulse absorbed. This paper will present the details of the heat load sources, of the pulse load leveling scheme operations, a partial helium schematic, dewar temperature as a function of time, the heat load sources as a function of time and the helium temperature as a function of length along the various components that will be cooled.
Date: September 29, 1995
Creator: Felker, B.; Slack, D.S. & Wendland, C.R.
Partner: UNT Libraries Government Documents Department

Fundamental mode rectangular waveguide system for electron-cyclotron resonant heating (ECRH) for tandem mirror experiment-upgrade (TMX-U)

Description: We present a brief history of TMX-U's electron cyclotron resonant heating (ECRH) progress. We emphasize the 2-year performance of the system, which is composed of four 200-kW pulsed gyrotrons operated at 28 GHz. This system uses WR42 waveguide inside the vacuum vessel, and includes barrier windows, twists, elbows, and antennas, as well as custom-formed waveguides. Outside the TMX-U vessel are directional couplers, detectors, elbows, and waveguide bends in WR42 rectangular waveguide. An arc detector, mode filter, eight-arm mode converter, and water load in the 2.5-in. circular waveguide are attached directly to the gyrotron. Other specific areas discussed include the operational performance of the TMX-U pulsed gyrotrons, windows and component arcing, alignment, mode generation, and extreme temperature variations. Solutions for a number of these problems are described.
Date: December 1, 1983
Creator: Rubert, R.R.; Felker, B.; Stallard, B.W. & Williams, C.W.
Partner: UNT Libraries Government Documents Department

Microwave measurement test results of circular waveguide components for electron cyclotron resonant heating (ECRH) of the Tandem Mirror Experiment-Upgrade (TMX-U)

Description: Development of high-power components for electron cyclotron resonant heating (ECRH) applications requires extensive testing. In this paper we describe the high-power testing of various circular waveguide components designed for application on the Tandem Mirror Experiment-Upgrade (TMX-U). These include a 2.5-in. vacuum valve, polarizing reflectors, directional couplers, mode converters, and flexible waveguides. All of these components were tested to 200 kW power level with 40-ms pulses. Cold tests were used to determine field distribution. The techniques used in these tests are illustrated. The new high-power test facility at Lawrence Livermore National Laboratory (LLNL) is described and test procedures are discussed. We discuss the following test results: efficiency at high power of mode converters, comparison of high power vs low power for waveguide components, and full power tests of the waveguide system. We also explain the reasons behind selection of these systems for use on TMX-U.
Date: December 1, 1983
Creator: Williams, C.W.; Rubert, R.R.; Coffield, F.E.; Felker, B.; Stallard, B.W. & Taska, J.
Partner: UNT Libraries Government Documents Department

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

TMX-Upgrade neutral-beam injection system

Description: The TMX experiment proved that axial confinement of central-cell ions is improved ninefold by the electrostatic potential of end-cell plasmas. The TMX Upgrade task is to improve this confinement further. This paper discusses the injector system aspects of the TMX Upgrade.
Date: October 5, 1981
Creator: Felker, B.; Kane, R.J.; Wong, R.L.; Calderon, M.O. & Moore, T.L.
Partner: UNT Libraries Government Documents Department

Microwave system for the microwave tokamak experiment (MTX)

Description: The microwave system for the Microwave Tokamak Experiment (MTX) will include part of the Lower Hybrid Heating (LHH) system used at Massachusetts Institute of Technology (MIT) on the Alcator machine and the new Free Electron Laser (FEL) microwave system being developed at LLNL. The LHH system for MTX will be two carts of four klystrons, each with a nominal total power of 2.1 MW at 4.6 GHz. The FEL system will deliver 2-MW average power at 250 GHz. 50 ns pulses every 200 ..mu..s of 8 gigawatt peak power will deliver the 2-MW average power. This paper will present both the LHH system from MIT and the FEL transmission system, which includes the master oscillator, launch into the FEL, mirrors, and transport system into the MTX. The microwave transmission system, microwave beam diagnostics, present design status, and other related issues will be presented. The MTX joins two devices, ETA-II and Alcator-C, through a beamline. 4 figs., 4 tabs.
Date: October 1, 1987
Creator: Felker, B.; Ferguson, W.; Heefner, J.; Krause, K.; Makowski, M. & Yamamoto, R.
Partner: UNT Libraries Government Documents Department

Mirror fusion test facility plasma diagnostics system

Description: During the past 25 years, experiments with several magnetic mirror machines were performed as part of the Magnetic Fusion Energy (MFE) Program at LLL. The latest MFE experiment, the Mirror Fusion Test Facility (MFTF), builds on the advances of earlier machines in initiating, stabilizing, heating, and sustaining plasmas formed with deuterium. The goals of this machine are to increase ion and electron temperatures and show a corresponding increase in containment time, to test theoretical scaling laws of plasma instabilities with increased physical dimensions, and to sustain high-beta plasmas for times that are long compared to the energy containment time. This paper describes the diagnostic system being developed to characterize these plasma parameters.
Date: November 8, 1979
Creator: Thomas, S.R. Jr., Coffield, F.E.; Davis, G.E. & Felker, B.
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

Polarizing holographic reflector for electron cyclotron resonant heating (ECRH) on the Tandem Mirror Experiment Upgrade (TMX-U)

Description: A reflector for electron cyclotron resonant heating on the Tandem Mirror Experiment Upgrade has been designed to convert the high-power TE/sub 01/ output of the circular waveguide system into a linearly polarized gaussian intensity pattern in the plasma. The reflector is a computer-generated holographic optical element with a twist polarizer. Its design, fabrication, and performance are discussed. Results of the low- and high-power tests are presented. Low-power tests were used to determine the beam pattern and the degree of cross-polarization. High-power tests verified that arcing across the grooves of the twist polarizer does not occur.
Date: November 14, 1983
Creator: Coffield, F.E.; Felker, B.; Gallagher, N.C. Jr.; Pedrotti, L.R.; Stallard, B.W.; Sweeney, D.W. et al.
Partner: UNT Libraries Government Documents Department

FENIX experimental results of large-scale CICC made of bronze-processed Nb{sub 3}Sn strands

Description: The Fusion ENgineering International eXperiments (FENIX) Test Facility recently has successfully complete the testing of a pair of Nb{sub 3}rSn cable-in-conduit conductors developed by the Japan Atomic Energy Research Institute. These conductors, made of bronze-processed strands, were designed to operate stably with 40-kA transport current at a magnetic field of 13 T. In addition to the measurements of major design parameters such as current-sharing temperature, FENIX provided several experiments specifically designed to provide results urgently needed by magnet designers. Performed experiments include measurements of ramp-rate limit, current-distribution, stability, and joint performance. This paper presents the design and results of these special experiments.
Date: October 13, 1994
Creator: Shen, S.S.; Felker, B.; Moller, J.M.; Parker, J.M.; Isono, T.; Yasukawa, Y. et al.
Partner: UNT Libraries Government Documents Department

Changes and developments in Electron Cyclotron Resonant Heating (ECRH) on the Tandem Mirror Experiment Upgrade (TMX-U)

Description: This paper will describe changes to the previously reported Electron Cyclotron Resonant Heating (ECRH) circular waveguide systems that deliver power to the Tandem Mirror Experiment Upgrade (TMX-U) machine. Four gyrotrons and associated waveguide systems, operating at 28-GHz and 200 kW each, helped establish electrostatic plugging in the end cells of TMX-U. A fifth gyrotron has been installed to power two resonant locations in the end plugs. This system and the pair of 10 kG heaters now use a slot radiator to obtain a more uniform coverage of the plasma. In addition, four 18-GHz ECRH systems have been added to the machine. 3 refs., 7 figs.
Date: November 14, 1985
Creator: Anderson, A.T.; Brooksby, C.A.; Calderon, M.O.; Ellis, R.; Felker, B.; Horton, R.D. et al.
Partner: UNT Libraries Government Documents Department

Assessment and Mitigation of Diagnostic-Generated Electromagnetic Interference at the National Ignition Facility

Description: Electromagnetic interference (EMI) is an ever-present challenge at laser facilities such as the National Ignition Facility (NIF). The major source of EMI at such facilities is laser-target interaction that can generate intense electromagnetic fields within, and outside of, the laser target chamber. In addition, the diagnostics themselves can be a source of EMI, even interfering with themselves. In this paper we describe EMI generated by ARIANE and DIXI, present measurements, and discuss effects of the diagnostic-generated EMI on ARIANE's CCD and on a PMT nearby DIXI. Finally we present some of the efforts we have made to mitigate the effects of diagnostic-generated EMI on NIF diagnostics.
Date: April 20, 2012
Creator: Brown, C. G.; Ayers, M. J.; Felker, B.; Ferguson, W.; Holder, J P; Nagel, S. R. et al.
Partner: UNT Libraries Government Documents Department

Design and fabrication of circular and rectangular components for electron-cyclotron-resonant heating of tandem mirror experiment-upgrade

Description: The electron-cyclotron-resonant heating (ECRH) systems of rectangular waveguides on Tandem Mirror Experiment-Upgrade (TMX-U) operated with a overall efficiency of 50%, each system using a 28-GHz, 200-kW pulsed gyrotron. We designed and built four circular-waveguide systems with greater efficiency and greater power-handling capabilities to replace the rectangular waveguides. Two of these circular systems, at the 5-kG second-harmonic heating locations, have a total transmission efficiency of >90%. The two systems at the 10-kG fundamental heating locations have a total transmission efficiency of 80%. The difference in efficiency is due to the additional components required to launch the microwaves in the desired orientation and polarization with respect to magnetic-field lines at the 10-kG points. These systems handle the total power available from each gyrotron but do not have the arcing limitation problem of the rectangular waveguide. Each system requires several complex components. The overall physical layout and the design considerations for the rectangular and circular waveguide components are described here.
Date: November 18, 1983
Creator: Felker, B.; Calderon, M.O.; Chargin, A.K.; Coffield, F.E.; Lang, D.D.; Rubert, R.R. et al.
Partner: UNT Libraries Government Documents Department

Circular waveguide systems for electron-cyclotron-resonant heating of the tandem mirror experiment-upgrade

Description: Extensive use of electron cyclotron resonant heating (ECRH) in the Tandem Mirror Experiment-Upgrade (TMX-U) requires continuous development of components to improve efficiency, increase reliability, and deliver power to new locations with respect to the plasma. We have used rectangular waveguide components on the experiment and have developed, tested, and installed circular waveguide components. We replaced the rectangular with the circular components because of the greater transmission efficiency and power-handling capability of the circular ones. Design, fabrication, and testing of all components are complete for all systems. In this paper we describe the design criteria for the system.
Date: November 18, 1983
Creator: Felker, B.; Calderon, M.O.; Chargin, A.K.; Coffield, F.E.; Gallagher, N.C. Jr.; Lang, D.D. et al.
Partner: UNT Libraries Government Documents Department

The Neutron Imaging System Fielded at the National Ignition Facility

Description: We have fielded a neutron imaging system at the National Ignition Facility to collect images of fusion neutrons produced in the implosion of inertial confinement fusion experiments and scattered neutrons from (n, n') reactions of the source neutrons in the surrounding dense material. A description of the neutron imaging system will be presented, including the pinhole array aperture, the line-of-sight collimation, the scintillator-based detection system and the alignment systems and methods. Discussion of the alignment and resolution of the system will be presented. We will also discuss future improvements to the system hardware.
Date: October 24, 2011
Creator: Fittinghoff, D N; Atkinson, D P; Bower, D E; Drury, O B; Dzenitis, J M; Felker, B et al.
Partner: UNT Libraries Government Documents Department