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in subjects: "Waveguides"

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Power excitation by the use of a rf wiggler

It is well-known that there are difficulties to obtain rf power sources of significant amount for frequencies larger than 3 GHz. Yet, rf sources in the centimeter/millimeter wavelength range would be very useful to drive, for example, high-gradient accelerating linacs for electron-positron linear colliders. We would like to propose an alternative method to produce such radiation. It makes use of a short electron bunch traveling along the axis of a waveguide which is at the same time excited by … more

Date: January 1, 1992

Creator: Ruggiero, Alessandro G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

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

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 tes… more

Date: December 1, 1983

Creator: Williams, C.W.; Rubert, R.R.; Coffield, F.E.; Felker, B.; Stallard, B.W. & Taska, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A coaxial converter for transforming a whispering gallery mode to the HE sub 11 mode

A coaxial analogue of the Vlasov converter is described which transforms a whispering gallery mode into an oversize rectangular TE{sub 01} mode, which can in turn be transformed into the HE{sub 11} mode by standard techniques. 5 refs., 4 figs.

Date: August 1, 1991

Creator: Moeller, C.P. & Doane, J.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The Two-beam accelerator

The Two-Beam Accelerator (TBA) consists of a long high-gradient accelerator structure (HGS) adjacent to an equal-length Free Electron Laser (FEL). In the FEL, a beam propagates through a long series of undulators. At regular intervals, waveguides couple microwave power out of the FEL into the HGS. To replenish energy given up by the FEL beam to the microwave field, induction accelerator units are placed periodically along the length of the FEL. In this manner it is expected to achieve gradients… more

Date: June 1, 1986

Creator: Sessler, A. M. & Hopkins, D. B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Measurements of ICRF (ion cyclotron range of frequencies) loading with a ridged waveguide coupler on PLT

An ICRF ridged waveguide coupler has been installed on PLT for measurements of plasma loading. The coupler was partially filled with TiO/sub 2/ dielectric in order to sufficiently lower the cutoff frequency and utilized a tapered ridge for improved matching. Vacuum field measurements indicated a single propagating mode in the coupler and emphasized the importance of considering the fringing fields at the mouth of the waveguide. Low power experiments were carried out at 72.6 and 95.0 MHz without… more

Date: November 1, 1987

Creator: Greene, G. J.; Wilson, J. R.; Colestock, P. L.; Fortgang, C. M.; Hosea, J. C.; Hwang, D. Q. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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GRILL: a code to calculate the spectrum of lower-hybrid waves launched by a Brambilla waveguide array

A computer code for calculating the predictions of the Brambilla theory of lower-hybrid wave launching is documented.

Date: June 1, 1980

Creator: Boley, C. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Torsional ultrasonic technique for reactor vessel liquid level measurement

We have undertaken a detailed study of an ultrasonic waveguide employed as a level, density, and temperature sensor. The purpose of this study was to show how such a device might be used in the nuclear power industry to provide reliable level information with a multifunction sensor, thus overcomming several of the errors that led to the accident at Three Mile Island. Some additional work is needed to answer the questions raised by the current study, most noticably the damping effects of flowing… more

Date: January 1, 1983

Creator: Dress, W. B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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

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 dete… more

Date: December 1, 1983

Creator: Rubert, R.R.; Felker, B.; Stallard, B.W. & Williams, C.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Coupling to the fast wave via a phased waveguide array

A dielectric-loaded waveguide array has been used to launch fast waves into a plasma in which ..omega../sup pi/ < ..omega.. << ..omega../sub pe/ approx. ..omega../sub ce/. The wave propagates when accessibility and cutoff requirements are satisfied. Reflection coefficients as low as 1% have been measured. Use of the fast wave for steady-state current drive is suggested.

Date: March 1, 1984

Creator: Olson, L.; McWilliams, R.; Glanz, J. & Motley, R. W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Master oscillator stability requirements considerations

This note attempts to point out some ideas about the required stability of the 476 MHz master oscillator, assuming that the phase noise of the oscillator is the only source of noise in the accelerator system.

Date: June 24, 1986

Creator: Schwarz, H. & Vancraeynest, J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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

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 pa… more

Date: August 1, 1991

Creator: Vernon, R.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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A high-power SLED 2 pulse compression system

The enhancement of peak power by means of RF pulse compression has found important application for driving high energy electron linacs, the SLAC linac in particular. The SLAC Energy Doubler (SLED), however, yields a pulse shape in the form of a decaying exponential which limits the applicability of the method. Two methods of improving this situation have been suggested: binary pulse compression (BPC), in which the pulse is compressed by successive factors of two, and SLED II in which the pair o… more

Date: March 1, 1992

Creator: Kroll, N. M.; Farkas, Z. D.; Lavine, T. L.; Menegat, A.; Ruth, R. D.; Wilson, P. B. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Overmoded waveguide components for the ECH system on PDX

Waveguide components designed specifically for transmitting power into PDX for electron cyclotron heating (ECH) at 60 GHz are described. These include mode converters from the circular electric TE01 mode to the polarized HE11 mode, compact corrugated waveguide bends with a hyperbolic secant curvature variation, compact corrugated waveguide diameter tapers with a parabolic profile, and a high voltage dc break incorporating a section of dielectric waveguide, all designed for low-loss HE11 propaga… more

Date: January 1, 1984

Creator: Doane, J.L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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A three-gap klystron output cavity at X-band

A high-power X-band klystron employing a double-gap output cavity has been operating at SLAC. Multi-gap output circuits have lower surface gradients at the interaction gaps than single-gap ones but are prone to self-oscillate due to negative loading and trapped higher-order modes. In the double-gap circuit design, considerable attention had been directed to deal with these stability problems. The performance of the present tube appears to be limited by gap breakdown and beam interception partic… more

Date: March 1, 1992

Creator: Ko, K.; Lee, T.G.; Tonegawa, S. (Stanford Linear Accelerator Center, Menlo Park, CA (United States)) & Kroll, N. (Stanford Linear Accelerator Center, Menlo Park, CA (United States) California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics)

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Discrete cavity model of a standing-wave free-electron laser

A standing-wave free-electron laser (SWFEL) has been proposed for use in a two-beam accelerator (TBA). Unlike a conventional microwave free-electron laser, the SWFEL has a wiggler that is divided by irises into a series of standing-wave cavities, and the beam is reaccelerated by induction cells between cavities. We introduce a one-dimensional discrete-cavity model of the SWFEL. In contrast to the continuum model that has been extensively used to study the device, the new model takes into accoun… more

Date: August 1, 1991

Creator: Rangarajan, G.; Sessler, A. (Lawrence Berkeley Lab., CA (United States)) & Sharp, W.M. (Lawrence Livermore National Lab., CA (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Three-dimensional calculations of fields and loading for loop and folded waveguide ICRF antennas

The ANT and ORION codes have been combined and used to study the loading of various antenna geometries with simple three-dimensional (3-D) effects. Both codes use a slab model with periodic Fourier analysis for modeling the toroidal and poloidal directions. The ANT code is used to prescribe current sets in a vacuum region where the field solutions are obtained analytically of each Fourier mode and matching conditions are used at poloidal/toroidal current sheet locations. Multiple current sheets… more

Date: January 1, 1991

Creator: Carter, M. D.; Baity, F. W.; Batchelor, D. B.; Hoffman, D. J.; Jaeger, E. F.; Swain, D. W. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Electromagnetic fields in an axial symmetric waveguide with variable cross section

A new class of separable variables is found which allows one to find an approximate analytical solution of the Maxwell equations for axial symmetric waveguides with slow (but not necessarily small) varying boundary surfaces. An example of the solution is given. Possible applications and limitations of this approach are discussed.

Date: July 1, 1980

Creator: Kheifets, S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Start-up and ramp-up of the PLT tokamak by lower hybrid waves

Lower hybrid waves have been used on the PLT tokamak both to start the plasma current and to ramp it up from pre-existing levels. The waves, at 800 MHz, were launched from a 6-waveguide grill. The phasing between adjacent guides could be selected electronically, and thus the launched spectrum could be set and changed at will. For start-up, the waveguide phase difference was initially set at 0/sup 0/ in order to create a plasma, then switched to 90/sup 0/ to drive the current. Over 100 kA of pla… more

Date: August 1, 1985

Creator: Jobes, F. C.; Bernabei, S.; Chu, T. K.; Fisch, N. J.; Hooke, W. M.; Karney, C. F. F. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Laser driven grating linac

The fields induced over a grating exposed to plane parallel light are explored. It is shown that acceleration is possible if either the particles travel skew to the grating lines, or if the radiation is falling at a skew angle onto the grating. A general theory of diffraction in this skew case is given. In one particular case numerical solutions are worked out for some deep grating. It is found that accelerating fields larger even than the initial fields can be obtained, the limit being set by … more

Date: January 1, 1980

Creator: Palmer, R B

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Predicted performance of an Induction Linac Driven FEL amplifier designed for radar applications at 94 GHz

The saturated performance of an Induction Linac Driven FEL operating at 94 GHz with peak microwave powers in excess of 2 GW is evaluated using a self-consistent 3D waveguide mode-particle interaction code. The code includes the effect of AC longitudinal space charge and DC transverse space charge with the resulting prediction that operation is not possible below 2.5 MeV with a 2 kA beam and 10 cm wiggler. A design based around a 4 MeV beam predicts peak power in excess of 2.4 GW over a 10% band… more

Date: August 1, 1991

Creator: Caplan, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Some numbers on the SLAC klystron windows

The attenuation in our standard copper rectangular wave guides at 10 cm wave length is known to be 0.7 db/100 ft. If the wave guide were made of 70/30 Cupro-nickel, the same alloy the window sleeve is made of, the attenuation constant would go up by the inverse square root of the ratio of the conductivities (skin effect formula). Thus the attenuation constant would be ..beta.. = 12.8 10/sup -3/ m/sup -1/. The length of the sleeve L = 23 mm. Hence a piece of rectangular wave guide of equal lengt… more

Date: March 1, 1984

Creator: Krienen, F.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Class of deflection-modulated, high-power microwave amplifiers

An unusual deflection-modulated, fast-wave electron device is analyzed. It has several unique properties; the electron beam is unbunched and is perpendicular to the direction of power flow in the circuit, and the circuit could be a simple fundamental-mode rectangular waveguide. The amplifier consists of an electron gun, a deflection cavity, an optional beam-bending system, and an output interaction region. An idealized theory showing that 100 percent electronic efficiency may be achieved, and s… more

Date: January 1, 1977

Creator: Tallerico, P.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Conversion of power and frequency

This paper deals with a novel idea to excite electrons to radiate energy in the short (millimeter) wavelength range. A short electron bunch is made to travel along the axis of a waveguide where a TM electromagnetic wave is also traveling and causes the beam to perform transverse oscillations. The electrons radiate energy as a consequence of the oscillations. It is found that a convenient mode of operation is to drive the waveguide in proximity of the cut-off.

Date: January 1, 1992

Creator: Ruggiero, A. G. & Wei, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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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)

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… more

Date: September 27, 1989

Creator: Ferguson, S.W.; Stever, R.; Throop, A.; Felker, B. & Franklin, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department