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in subjects: "Resonators"

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Numerical simulation of a short RFQ resonator using the MAFIA codes

The electrical characteristics of a short (2{beta}{lambda}=0.4 m) resonator with large modulation (m=4) have been studied using the three dimensional codes, MAFIA. The complete resonator, including the modulated electrodes and a complex support structure, has been simulated using {approximately} 350,000 mesh points. Important characteristics studied include the resonant frequency, electric and magnetic fields distributions, quality factor and stored energy. The results of the numerical simulati… more

Date: January 1, 1991

Creator: Wang, H.; Ben-Zvi, Ilan; Jain, A.; Paul, P. (State Univ. of New York, Stony Brook, NY (United States). Dept. of Physics) & Lombardi, A. (Istituto Nazionale di Fisica Nucleare, Legnaro (Italy). Lab. Nazionale di Legnaro)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Microwave longitudinal coupling impedance in ISABELLE vacuum chamber

The purpose of this paper is to investigate the modes above the cutoff frequency of the ISABELLE vacuum chamber, and to measure some typical values of the longitudinal coupling impedance. (The investigation was limited to only those modes that have fields in the beam pipe.) Measurements show that the impedance, Z, between 2.6 and 2.8 GHz, can be as high as 10 x n ohms, where n is the ratio of the excitation frequency of the beam divided by the fundamental rotational frequency of the ISABELLE ri… more

Date: March 1, 1980

Creator: Giordano, S. & Votruba, J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Advanced accelerator research at Argonne

A facility with which to experimentally measure methods of advanced acceleration is at the point of completion at Argonne National Laboratory. The new facility consists a system which produces pulse ''doublets'' of energetic electrons, pulse shaping hardware, a space for experimental apparatus, and a high resolution spectrometer. The leading 21 MeV pulse in a doublet can contain up to 15 nano-coulombs of charge and can be adjusted to be from 6 to over 100 pic-seconds in length. The trailing dou… more

Date: January 1, 1986

Creator: Konecny, R.; MacLachlan, J.; Norem, J.; Ruggiero, A.; Schoessow, P. & Simpson, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The laser switched linac and development of a high brilliance electron source

This task originated in 1987 to explore the possibility of accelerating short bursts of electrons by pulsed power. The principal effort of our group was to demonstrate that electrons can be accelerated by picosecond-long electrical pulses which are compressed in a radial transmission line. This goal has new been achieved and our results are presented in this paper. We have achieved a gradient of 45 MV/m across a 250 {mu}m accelerating gap and have accelerated 10{sup 6} electrons in a 1 ps long … more

Date: September 1, 1991

Creator: Melissinos, A.C.; Bamber, C.; Blalock, T.; Fry, A. & Wilson, T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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A bulk niobium superconducting quarter wave resonator

A bath-cooled all-niobium 160 MHz quarter wave resonator prototype was constructed and tested. The objective of this research has been the development of a high performance accelerating element with {beta}{sub opt} {approx equal} 0.11 for the ALPI linac at the Laboratori Nazionali di Legnaro. The design of this resonator was based upon a previous 150 MHz model, with minor changes due to the different frequency and to modified welding procedure. An accelerating field of 5 MV/m was achieved at a … more

Date: January 1, 1990

Creator: Ben-Zvi, Ilan; Chiaveri, E.; Elkonin, B. V.; Facco, A. & Sokolowski, J. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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NBS-LASL racetrack microtron

The NBS-LASL racetrack microtron (RTM) is a joint project of the National Bureau of Standards (NBS) and the Los Alamos Scientific Laboratory (LASL). This is a new accelerator research project whose goal is to determine the feasibility of building a high-energy, high-current, cw electron accelerator using beam recirculation and room-temperature rf acceleration structures. The NBS-LASL RTM is being designed and built to develop the required technology for a large national 1 to 2 GeV cw accelerato… more

Date: January 1, 1980

Creator: Penner, S.; Debenham, P.H. & Green, D.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Frontiers of particle beam physics

First, a review is given of various highly-developed techniques for particle handling which are, nevertheless, being vigorously advanced at the present time. These include soft superconductor radio frequency cavities, hard superconductor magnets, cooling rings for ions and anti-protons, and damping rings for electrons. Second, attention is focused upon novel devices for particle generation, acceleration, and focusing. These include relativistic klystrons and free electron laser power sources, b… more

Date: November 1, 1989

Creator: Sessler, Andrew M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Seismic isolation of an electron microscope

A unique two-stage dynamic-isolation problem is presented by the conflicting design requirements for the foundations of an electron microscope in a seismic region. Under normal operational conditions the microscope must be isolated from ambient ground noise; this creates a system extremely vulnerable to seismic ground motions. Under earthquake loading the internal equipment forces must be limited to prevent damage or collapse. An analysis of the proposed design solution is presented. This study… more

Date: January 1, 1980

Creator: Godden, W.G.; Aslam, M. & Scalise, D.T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Brazing techniques for side-coupled electron accelerator structures

The collaboration between the Los Alamos National Laboratory and the National Bureau of Standards (NBS), started in 1979, has led to the development of an advanced c-w microtron accelerator design. The four 2380-MHz NBS accelerating structures, containing a total of 184 accelerating cavities, have been fabricated and delivered. New fabrication methods, coupled with refinements of hydrogen-furnace brazing techniques described in this paper, allow efficient production of side-coupled structures. … more

Date: January 1, 1986

Creator: Hansborough, L. D.; Clark, W. L.; DePaula, R. A.; Martinez, F. A.; Roybal, P. L.; Wilkerson, L. C. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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On bunch lengthening using the fourth harmonic cavity in the NSLS VUV ring

It has been suggested that the phase of the beam excited voltage in the harmonic cavity can be controlled by detuning its resonant frequency from the beam current harmonic. Unfortunately the detuning needed to flatten the acceleration waveform also corresponds to the region of Robinson instability for the harmonic cavity. Therefore, lengthening the bunch may be followed by large amplitude synchrotron oscillation of the bunch center of mass. Bunch lengthening is discussed in this note from sever… more

Date: February 1, 1988

Creator: Wachtel, J.M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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BNL RFQ

A brief outline of the theoretical design has been presented at the Symposium. Particular emphasis has been placed on the rf design of the main cavity, end cells, and power feed. The relevance of the design has been considered with respect to the tuning and operating characteristics of the structure.

Date: January 1, 1983

Creator: Giordano, S.T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Three-dimensional simulation of a hole-coupled FEL oscillator

The performance of a two-mirror resonator with holes for out-coupling has been examined in a previous study in which the FEL gain was neglected, but the geometrical effect of the wiggler aperture was included in the optical calculation. The phenomenon of mode degeneracy was found to occur, that has serious implications for the stability of performance when the FEL gain is included. We have developed a FEL oscillator code based on TDA'', a three-dimensional FEL amplifier code, to study the mode … more

Date: August 1, 1991

Creator: Krishnagopal, S.; Xie, M.; Kim, K. J. & Sessler, A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Pump down rate for SRF cavities

This note is about calculations aimed at quantifying adequate pumping speeds of evacuation of normally humid clean-room air from typical Superconducting Radiofrequency (SRF) cavities. The subject is of high relevance to the semiconductor industry, where the yield of VLSI (Very Large Scale Integration) chip production is affected by micron size particles which may cause fatal defects to their micron and sub-micron features. The recent availability of particle counters capable of operating in vac… more

Date: February 1, 1992

Creator: Kuchnir, M. (Fermi National Accelerator Lab., Batavia, IL (United States)) & Knobloch, J. (Cornell Univ., Ithaca, NY (United States). Lab. of Nuclear Studies)

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Toward more accurate loss tangent measurements in reentrant cavities

Karpova has described an absolute method for measurement of dielectric properties of a solid in a coaxial reentrant cavity. His cavity resonance equation yields very accurate results for dielectric constants. However, he presented only approximate expressions for the loss tangent. This report presents more exact expressions for that quantity and summarizes some experimental results.

Date: May 1, 1980

Creator: Moyer, R. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Development of a heavy-ion linac based on superconducting interdigital accelerating structures

Four types of superconducting accelerating structures are being developed for use in a low-velocity positive-ion injector linac planned for ATLAS heavy-ion accelerator. A prototype of the first of these, an interdigital four-gap structure, has been completed and tested at accelerating gradients up to 10 MV/m, corresponding to a maximum surface electric field of 40 MV/m and an effective accelerating potential of 1 MV/resonator. The 48.5 MHz resonant cavity has an active length of 10 cm and is de… more

Date: January 1, 1986

Creator: Shepard, K.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Recent developments in thermoacoustically-driven low-frequency projectors

Thermoacoustic engines are a recent class of devices that can efficiently convert heat to acoustic energy without moving parts or intervening mechanisms. These engines have a natural potential for powering low-frequency sonar projectors with high reliability and efficiencies that cannot be matched by conventional technologies. A recent design study has produced thermoacoustic projector configurations that can execute standard projector performance requirements such as FM sweep and velocity magn… more

Date: January 1, 1992

Creator: Ward, W.C. & Merrigan, M.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Automatic network analyzer procedures for 5045 klystron cavities

This Note describes the results of using Automatic Network Analyzers in measuring SLAC 5045 klystron cavities. Two different analyzers were compared; the HP8753 and HP8510. Both analyzers have frequency synthesizer accuracy and stability to perform the measurement without the need for a frequency counter. The klystron has six cavities which can be put into three categories; input, gain and output. The input and output cavities require an external Q measurement (Qe) to determine coupling ({beta}… more

Date: July 1, 1991

Creator: Judkins, J.G.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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High power testing of the prototype accelerating cavity (352 MHz) for the advanced photon source (APS)

Measurement of the higher order of modes of a prototype single-cell 352 MHz cavity for the APS 7-Gev storage ring will be presented and discussed. A cavity made from solid copper was built according to dimensions derived from URMEL program runs. The longitudinal and transverse impedances of the first several higher order modes have been measured using various-shaped metal beads. High power ( > 60 kW) testing of the cavity will be described along with design and operation of dampers for those mo… more

Date: January 1, 1992

Creator: Bridges, J.F.; Kang, Y.W.; Kustom, R.L. & Primdahl, K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Proceedings of the third workshop on RF (radiofrequency) superconductivity

Separate abstracts were prepared for 26 papers in these proceedings. (LEW)

Date: January 1, 1988

Creator: Shepard, K.W. (ed.)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Resonator design for a visible wavelength free-electron laser (*)

Design requirements for a visible wavelength free-electron laser being developed at the Accelerator Test Facility at Brookhaven National Laboratory are presented along with predictions of laser performance from 3-D numerical simulations. The design and construction of the optical resonator, its alignment and control systems are also described. 15 refs., 8 figs., 4 tabs.

Date: January 1, 1990

Creator: Bhowmik, A.; Lordi, N. (Rockwell International Corp., Canoga Park, CA (United States). Rocketdyne Div.); Ben-Zvi, Ilan & Gallardo, J. (Brookhaven National Lab., Upton, NY (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Status of the SUNY superconducting RFQ

A RFQ resonator is presently being developed at SUNY. This resonator is a prototype for a chain of six short ({approximately}0.5m long), superconducting (Pb plated Cu), 50 MHz resonators designed to accelerate beam from {beta} = 0.01 to 0.05. The chain accepts a prebunched beam to save on superconducting length. The resonators are of four-rods type with vane-like electrodes. The prototype resonator is designed to accelerate ions of q/A = 1/6 from {beta} = 0.030 to 0.036, operating at a peak sur… more

Date: January 1, 1991

Creator: Jain, A.; Ben-Zvi, Ilan; Paul, P.; Wang, H. (Brookhaven National Lab., Upton, NY (United States)) & Lombardi, A. (Istituto Nazionale di Fisica Nucleare, Legnaro (Italy). Lab. Nazionale di Legnaro)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Experimental studies of the beam-breakup mode on ETA: comparison with theory

The beam breakup mode has been observed and measured on ETA. Comparison between the measurements and the results of a computer code indicate that the beam breakup instability will be the most important limitation on current transport thru ATA. ETA Experiments that will enable a more accurate determination of the magnitude of the instability on ATA are discussed.

Date: January 29, 1982

Creator: Caporaso, G.J. & Struve, K.W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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LEB tuner made out of titanium alloy

A proposed design of a closed shell tuner for the LEB cavity is presented. The tuner is made out of Ti alloy which has a high electrical resistivity as well as very good mechanical strength. Using this alloy results in a substantial reduction in the eddy current heating as well as allowing for faster frequency control. 9 figs.

Date: September 1, 1991

Creator: Goren, Y. & Campbell, B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Resonator modes in high gain free electron lasers

When the gain in a free electron laser is high enough to produce optical guiding, the resonator mode distorts and loses its forward-backward symmetry. We show that the resonator mode in a high gain FEL can be easily constructed using the mode expansion technique taken separately in the interaction and the free-space regions. We propose design strategies to achieve maximal gain and optimal mode quality, and discuss the stability of the optimized mode. 11 refs., 4 figs.

Date: October 1, 1989

Creator: Xie, Ming (Lawrence Berkeley Lab., CA (USA)); Deacon, D.A.G. (Deacon Research, Palo Alto, CA (USA)) & Madey, J.M.J. (Duke Univ., Durham, NC (USA). Dept. of Physics)

Item Type: Article

Partner: UNT Libraries Government Documents Department