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in subjects: "Resonators 430303* -- Particle Accelerators-- Experimental Facilities & Equipment"

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Single-cavity double-frequency buncher

A single-cavity buncher has been developed that resonates at both the fundamental and twice the fundamental frequency to form a more nearly ideal bunching voltage waveform in the gap. The cavity utilizes the TM/sub 020/-like mode as the first harmonic of the fundamental TM/sub 010/-like mode. Field distributions on or near the axis, which are seen by the beam, are essentially identical for the two modes. Many beam bunching applications require two bunchers with the harmonic buncher being physic… more

Date: January 1, 1979

Creator: Schriber, S.O. & Swenson, D.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The Los Alamos VXI-based modular RF control system

This paper describes the design and implementation of the Los Alamos modular RF control system, which provides high-performance feedback and/or feedforward control of RF accelerator cavities. This is a flexible, modular control system which has been realized in the industry-standard VXI cardmodular format. A wide spectrum of system functionality can be accommodated simply by incorporating only those modules and features required for a particular application. The fundamental principles of the de… more

Date: January 1, 1993

Creator: Jachim, S.P.; Ziomek, C.; Natter, E.F.; Regan, A.H.; Hill, J.; Eaton, L. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Buncher cavity resonant at the first and second harmonic

A buncher is an RF accelerator followed by a drift space. Its purpose is to bunch the dc ion source beam into suitable bunches for acceleration in a linac. The voltage in a simple buncher is a sine wave at the linac frequency. A more elaborate wave form can result in increased capture of ion source beam. The cavities discussed here are resonant at 12.5 and 25 MHz, the first and second harmonic of the Argonne National Laboratory (ANL) low beta linac. They will support a wave form which should gi… more

Date: January 1, 1979

Creator: Foss, M.H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Experimental and calculated rf properties of the disk-and-washer structure

A detailed study of the disk-and-washer structure using SUPERFISH has shown that the physical geometry can be optimized to make the structure more efficient than previously reported. The calculated ZT/sup 2/ is equal to that of an equivalent LAMPF cavity (neglecting any losses associated with the side-coupler slots) for ..beta.. = 0.6 and is 30% higher for ..beta.. = 1.0. Several techniques for supporting the washer were studied in addition to the conventional ''L'' supports. Two types of suppo… more

Date: January 1, 1979

Creator: Potter, J. M.; Schriber, S. O. & Humphry, F. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Beam Cavity Coupling Impedance

The beam-cavity coupling impedance is formulated in terms of the normal modes of the cavity. While the analysis is carried out only for the longitudinal beam-cavity coupling impedance, it should be easily adapted to the transverse impedance. The hope is that such a formulation may illuminate the behavior of the coupling impedance in various frequency limits.

Date: June 1984

Creator: Gluckstern, Robert

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Resonant impedance of bellows above cutoff

The perturbation method of Chatard-Moulin and Papiernik is used to calculate the longitudinal and transverse impedances, Z(..omega..) and Z/sub perpendicular/(..omega..), of a bellows. The bellows shape is defined by its radius a(z) = a (1 + epsilons(z)), where a is the mean radius, epsilon a small parameter, and s(z) describes the convolution of the bellows. A finite wall conductivity is considered and the resonant contribution to the impedance above the cutoff frequency of the unperturbed cha… more

Date: January 1, 1980

Creator: Krinsky, S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Vane fabrication for the proof-of-principle radio-frequency quadrupole accelerator

The electrodes for the Proof-of-Principle (POP) Radio-Frequency Quadrupole (RFQ) accelerator were machined on a numerically controlled, three-axis, vertical mill. These pole tips, or vanes, were prepared for, and used, in the successful demonstration of RFQ practicality at Los Alamos National Laboratory in February 1980. The data set that described the vanes contained about 10 million bits of tool position data. The vanes were cut from OFHC copper blanks. The tolerances achieved were approximat… more

Date: January 1, 1981

Creator: Williams, S. W. & Potter, J. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Some new methods of RF control

This presentation will focus on several recent developments at Los Alamos in the area of RF control for accelerators. Included in the discussion will be in-phase/quadrature (I/Q) field control, the application of six-port reflectometers for cavity instrumentation and resonance control, a technique for phase stabilization of critical RF cables, an application of state-variable feedback for field control, and the direct integration of RF and computer-interface hardware using the VXIbus standard. … more

Date: January 1, 1990

Creator: Jachim, S.P.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Development program for a 200 kW, CW, 110 GHz gyrotron. Quarterly report No. 1, June-September 1979

The objective of this program is the design and development of a millimeter-wave device to produce 200 kW of continuous-wave power at 110 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-varying rf load mismatch. Progress toward this goal is described and specifications of the gyrotron are … more

Date: January 1, 1979

Creator: Arnold, K.W.; Tancredi, J.J.; Caplan, M.; Ha, K.W.; Birnbaum, D.N. & Weiss, W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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FMIT prototype linac tank

The prototype linac tank (PLT) is an assembly of many components. This paper is limited to a discussion of the shell, and not the attaching components. Basically, the shell consists of an 8-ft-diam by 12-ft-long copper-lined tube. Despite the simplicity of this description, many special features not used nor needed in pulsed accelerators have been incorporated into this design, to handle the continuous duty cycle and high radiation levels expected for the Fusion Materials Irradiation (FMIT) Fac… more

Date: January 1, 1981

Creator: Coops, William

Item Type: Article

Partner: UNT Libraries Government Documents Department

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FMIT alignment cart

The Fusion Materials Irradiation Test (FMIT) Facility alignment cart must perform several functions. It must serve as a fixture to receive the drift-tube girder assembly when it is removed from the linac tank. It must transport the girder assembly from the linac vault to the area where alignment or disassembly is to take place. It must serve as a disassembly fixture to hold the girder while individual drift tubes are removed for repair. It must align the drift tube bores in a straight line para… more

Date: January 1, 1981

Creator: Potter, R. C.; Dauelsberg, L. B.; Clark, D. C. & Grieggs, R. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Resonators for heavily beam-loaded linacs

Capacitively loaded resonant line section accelerating structures are discussed. Prototype models were measured at low levels, and calculations were made to predict high level operation. High current composite beams of multiple-beamlets as accelerated by a MEQALAC were assumed.

Date: April 28, 1980

Creator: Sanders, R.T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Stability of klystron operation as a function of input parameters

Instabilities in the operation of a high-power multicavity klystron have been studied as a function of various input parameters. Among these, the focusing magnetic field, rf input power and tuning of the second harmonic cavity were observed to have a striking effect in deciding the regions of unstable operation. One region of instability could be identified with a value of magnetic field corresponding to cyclotron resonance, at the operating frequency. The magnetic field value in the region of … more

Date: March 1, 1984

Creator: Singh, A.; Konrad, G. T. & Griffin, C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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LAMPF 805-MHz accelerator structure tuning and its relation to fabrication and installation

In the course of construction of the 805-MHz linac, it was necessary to set 10,000 resonant cavities to precise frequencies and to check, and in some cases, to adjust the field distribution along the beam axis of the 104 rf tanks composing the linac. Since this was the first proton linac of the side-coupled type ever built, it was necessary to develop new techniques and instrumentation for structure tuning. An outline of the fabrication and installation process is given, showing how the tuning … more

Date: July 1, 1979

Creator: Swain, G.R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Microwave measurements of the ETA accelerating cavity

Microwave measurements of the ETA accelerating cavities have shown eleven resonances in the frequency range of 0 to 850 MHz. These modes have been identified according to their similarity with the modes of a cylindrical cavity. Measurements of the Q's of the modes yielded values from 14 to 70 and transverse shunt impedances (R/sub perpendicular/Q) of 9 to 12..cap omega... In particular, beam breakup mode (TM/sub 110/) has a Q of 20 to 40 and a transverse impedance of 9..cap omega... A later rep… more

Date: March 12, 1980

Creator: Birx, D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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rf coaxial couplers for high-intensity linear accelerators

Two rf coaxial couplers that are particularly suitable for intertank connection of the disk-and-washer accelerating structure for use in high-intensity linear accelerators have been developed. These devices have very high coupling to the accelerating structure and very low rf power loss at the operating frequency, and they can be designed for any relative particle velocity ..beta.. > 0.4. Focusing and monitoring devices can be located inside these couplers.

Date: February 1, 1980

Creator: Manca, J. J. & Knapp, E. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Voltage breakdown testing for the radio-frequency quadrupole accelerator

Designs of radio-frequency quadrupole (RFQ) accelerators with reasonable length require operation with surface fields above the limit imposed by Kilpatrick's Criterion. A cavity was designed using SUPERFISH to test the validity of this Criterion and to determine operating limits for the RFQ. The experimental setup and procedure are described, as are the data and results. A method of calibrating the test is presented.

Date: January 1, 1979

Creator: Williams, S. W.; Rodenz, G. W.; Humphry, F. J. & Potter, J. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Discontinuity effects on radial cavity transmission lines

Pulse propagation in radial cavity transmission lines such as those found on a radial line accelerator is considered. Specifically, the effects of discontinuities along the line are examined in detail. It is found that previous analyses of such effects have been incorrect, and here two alternate solution techniques are presented. Depending upon the parameters of such a radial line, the discontinuity effects considered here may or may not be significant; however, if they are significant, it is r… more

Date: April 1, 1979

Creator: Seidel, D.B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Development of 400- to 450-MHz RFQ resonator-cavity mechanical designs

In the development of the radio-frequency quadrupole (RFQ) linac, the resonator cavity's mechanical design may be a challenge similar in magnitude to that of the development of the accelerator structure itself. Experience with the all-copper 425-MHz RFQ proof-of-principle linac has demonstrated that the resonator cavity must be structurally stiff and easily tunable. This experience has led to development of copper-plated steel structures having vanes that may be moved within a cylinder for tuni… more

Date: January 1, 1982

Creator: Hansborough, L.D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Reduction of the beam breakup mode Q values in the ETA/ATA Accelerating Cells

Earlier Microwave Measurements of the ETA Accelerating Cells has uncovered eleven resonances in the frequency range of 0 > 850 MHz. The Q values of these modes ranged from 14 to 70. A three phase program directed at substantially reducing these Q values is reported. In particular the dampening methods described below resulted in a decrease of Q value from 40 to 5 for the beam breakup mode (TM/sub 110/) with a corresponding reduction for most of the other cavity modes.

Date: May 20, 1980

Creator: Birx, D.L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Room-temperature cavities for high-beta accelerating structures

Properties of several room-temperature cavities for standing-wave linear accelerator structures are discussed. In particular, new results related to the disk-and-washer geometry are presented. Extensive calculations using the computer program SUPERFISH have shown that the ..beta.. = 1.0 the effective shunt impedance is at least 20% higher than that of an equivalent LAMPF cavity, while quality factors can be a factor of two higher.

Date: January 1, 1979

Creator: Schriber, S.O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Unique space saving accelerator cavity design

A cavity with 3 series gaps was designed and modeled to operate at 70 MHz as a SuperHILAC post acceleration buncher (8.5 MeV/A). Because of a cross-coupling scheme, the 3 cells operate in the 1/2 ..beta.. lambda mode instead of the ..beta.. lambda mode of an Alvarez cavity. This coupling results in a cavity with diameter reduced from 3 to less than one meter and a length half that of an Alvarez cavity for the same energy gain. The 3 gaps are electrically in parallel but mechanically in series. … more

Date: March 1, 1981

Creator: Kim, H.; Fugitt, J.; Crosby, F. & Johnson, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Phenomenological method of calculating microwave longitudinal coupling impedances

A previous paper described an investigation of the longitudinal coupling impedance of the TM/sub olm/ modes in the ISA vacuum chamber. A method was developed for calculating these impedances by using the data derived from pertubation measurements. This method gave accurate results between 2.6 and 2.8 GHz, but above 2.8 GHz measurements became difficult because of the mixing of the TM/sub olm/ modes with other modes. This paper presents a phenomenological approach for calculating these impedance… more

Date: May 1, 1980

Creator: Giordano, S. & Votruba, J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Performance characteristics of a 425 MHz RFQ linac

A radio-frequency quadrupole (RFQ) focused proton linac has been developed and successfully tested at the Los Alamos Scientific Laboratory (LASL) for the purpose of evaluating its performance and applicability as a low-beta accelerator. The geometry of the structure was designed to accept a 100-keV beam, focus, bunch, and accelerate it to 640 keV in 1.1 m with a high-capture efficiency and minimum emittance growth. The accelerator test facility includes an injector, low-energy transport section… more

Date: 1980

Creator: Stovall, J. E.; Crandall, K. R. & Hamm, R. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department