35 Matching Results

Search Results

Advanced search parameters have been applied.
in subjects: "Resonators"  
Results: 1 - 24 next
open access

Pump down rate for SRF cavities

Description: 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: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Recent developments in thermoacoustically-driven low-frequency projectors

Description: 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: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

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

Description: 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: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Stability of Resonator Configurations in the Presence of Free-Electron Laser Interactions

Description: The stability of empty resonators (or cold cavities) has been widely studied, and is well understood. Here we consider the stability of symmetric resonator systems when there is a free-electron laser (FEL) interaction present within the cavity. We first construct a linear thick-lens model of the FEL and analytically study the dependence of resonator stability on its geometry. Next, we employ a nonlinear, three-dimensional FEL oscillator code to study the dependence of FEL performance on the cav… more
Date: November 1, 1992
Creator: Krishnagopal, S. & Sessler, Andrew M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Recent developments in rf superconductivity for high-brightness and high-gradient ion beam accelerators

Description: Recent progress in on-going development program leading to the design of superconducting continuous-wave (cw) linear accelerators for high-brightness ion beams is reviewed. A new spoke-resonator geometry incorporating a half-wavelength resonant line was fabricated and tested. This geometry serves as the basis for the constituent cavities of a superconducting section being designed for high-current testing with a deuterium beam. Considerable progress has been made in the design of this section. … more
Date: January 1, 1992
Creator: Delayen, J. R.; Bohn, C. L.; Kennedy, W. L.; Nichols, G. L.; Roche, C. T. & Sagalovsky, L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

RF cavity development for the PEP-II B factory

Description: This paper describes the development of an RF cavity design for the proposed PEP-II asymmetric B factory. The high luminosity required of PEP-II provides challenges in the design of the RF cavities, most notably in the reduced higher-order mode (HOM) impedances that must be attained and in the power that must be dissipated in the cavity walls. This paper outlines the goals set in these regards, describes how the cavity has been developed to meet them, and presents the results of measurements on… more
Date: November 1, 1992
Creator: Rimmer, R.A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

TESLA test cell cryostat support post thermal and structural analysis

Description: TeV Superconducting Linear Accelerator (TESLA) cryostats consist of eight, 1-meter-long radio frequency (RF) cavity modules cryogenically connected in series with one focusing quadrupole. Each module contains one, 9-cell superconducting RF cavity operating at 1.3 GHz in a 1.8K helium bath. Individual modules are self-contained in the that they have their own input couplers, high order mode couplers, and tuning mechanisms. Services common to the entire cryostat consist of 70K and 4.5K thermal ra… more
Date: August 15, 1992
Creator: Nicol, T.H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Higher order mode damping studies on the PEP-II B-Factory RF cavity

Description: We describe studies of the higher-order-mode (HOM) properties of the prototype 476 MHz RF cavity for the proposed PEP-II B-Factory and a waveguide damping scheme to reduce possible HOM-driven coupled-bunch beam instability growth. Numerical studies include modelling of the HOM spectrum using MAFIA and ARGUS, and calculation of the loaded Q's of the damped modes using data from these codes and the Kroll-Yu method. We discuss briefly the experimental investigations of the modes, which will be mad… more
Date: March 1, 1992
Creator: Rimmer, R.; Goldberg, D.; Lambertson, G.; Voelker, F. (Lawrence Berkeley Lab., CA (United States)); Ko, K.; Kroll, N. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

An infrared free electron laser system for the proposed Chemical Dynamics Research Laboratory at LBL based on a 500 MHz superconducting linac

Description: We describe a new design of the Infrared Free Electron Laser (IRFEL) for the proposed Chemical Dynamics Research Laboratory (CDRL) at LBL. The design and choice of parameters are dictated by the unique requirements of the CDRL scientific program. The accelerator system is based on the 500 MHz superconducting cavity technology to achieve a wavelength stability of 10[sup [minus]4].
Date: September 1, 1992
Creator: Kim, K. J.; Byrns, R.; Chattopadhyay, S.; Donahue, R.; Edighoffer, J.; Gough, R. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Suppression of mode-beating in a saturated hole-coupled FEL oscillator

Description: In a hole-coupled resonator, either empty or loaded with a linear FEL gain medium, the phenomenon of mode-degeneracy and mode-beating have been studied. When the magnitudes of the eigenvalues, derived from a linear analysis, are equal for two or more dominant eigenmodes, the system cannot achieve a stable beam-profile. We investigate this phenomenon when a saturated FEL is present within the cavity, thus introducing non-linearity. We use a three-dimensional FEL oscillator code, based on the amp… more
Date: August 1, 1992
Creator: Krishnagopal, S.; Xie, M. & Kim, K. J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Computer codes for RF cavity design

Description: In RF cavity design, numerical modeling is assuming an increasingly important role with the help of sophisticated computer codes and powerful yet affordable computers. A description of the cavity codes in use in the accelerator community has been given previously. The present paper will address the latest developments and discuss their applications to cavity toning and matching problems.
Date: August 1, 1992
Creator: Ko, K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Fabrication and test of a superconducting RFQ

Description: The fabrication and first performance tests of a prototype superconducting radio-frequency quadrupole resonator (SRFQ) are described. The SRFQ operates at 57 MHz and is optimized for a particle velocity of [beta] = 0.033. It is constructed of copper electroplated with a lead-tin alloy. An accelerating field gradient of 1.25 MV/m was achieved with about 7 watts of helium dissipation. This corresponds to an energy gain of 700 keV per unit charge over the 56 cm overall diameter of the resonator.
Date: January 1, 1992
Creator: Jain, A.; Wang, H.; Ben-Zvi, Ilan; Paul, P.; Noe, J. W. (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: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Investigation of alternating-phase focusing for superconducting linacs

Description: The paper describes a new model of alternating-phase focusing (APF) dynamics applicable to ion linacs with short independently controlled superconducting cavities. The equations of motion are derived for a cylindrically symmetric electric field represented by a traveling wave with continuous periodic phase modulation. solutions are obtained and analyzed for both the linear and nonlinear particle motion. Problems of linear stability and overall longitudinal acceptance are solved using standard m… more
Date: January 1, 1992
Creator: Sagalovsky, L. & Delayen, J. R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Design for a superconducting niobium RFQ structure

Description: This paper reports a design for a niobium superconducting RFQ operating at 192 Mhz. The structure is of the rod and post type, novel in that each of four rods is supported by two posts oriented radially with respect to the beam axis. Although the geometry has four-fold rotation symmetry, the dipole-quadrupole mode splitting is large, giving good mechanical tolerances. The simplicity of the geometry enables designing for good mechanical stability while minimizing tooling cost for fabrication wit… more
Date: January 1, 1992
Creator: Shepard, K. W.; Kennedy, W. L. & Sagalovsky, L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Upgraded phase control system for superconducting low-velocity accelerating structures

Description: Microphonic-induced fluctuations in the RF eigenfrequency of superconducting (SC) slow-wave structures must be compensated by a fast-tuning system in order to control the RF phase. The tuning system must handle a reactive power proportional to the product of the frequency range and the RF energy content of the Rf cavity. The fast tuner for the SC resonators in the ATLAS heavy-ion linac is a voltage-controlled reactance based on an array of PIN diodes operating immersed in liquid nitrogen. This … more
Date: January 1, 1992
Creator: Added, N. (Sao Paulo Univ., SP (Brazil). Dept. de Fisica Nuclear); Clifft, B. E. & Shepard, K. W. (Argonne National Lab., IL (United States))
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Calculation of mechanical vibration frequencies of stiffened superconducting cavities

Description: We calculated the frequencies of transverse and longitudinal mechanical-vibration modes of the HEPL- modified, CERN/DESY four-cell superconducting cavity, using finite-element techniques. We compared the results of these calculations, including the stiffening of the cavity with rods, with mode frequencies measured at HEPL. The correlation between data was significant. The same techniques were also used to design and optimize the stiffening scheme for the seven-cell 805-MHz superconducting cavit… more
Date: January 1, 1992
Creator: Black, S. J. & Spalek, G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Design and test of a superconducting structure for high-velocity ions

Description: Following the successful development of a niobium coaxial half-wave structure we have designed, built and tested a new half-wave geometry: the spoke resonator. This geometry is better suited for high frequency resonators and for the acceleration of high velocity ions. The prototype cavity is a 2-gap structure resonating at 855 MHz, and optimized for particle velocity of 0.30 c. It is easier to manufacture than the coaxial half-wave resonator and the geometry can be straightforwardly extended to… more
Date: January 1, 1992
Creator: Delayen, J. R.; Kennedy, W. L. & Roche, C. T.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Electron beam transport for the LBL IR-FEL. [Infrared free-electron laser]

Description: The infrared flee-electron laser (IR-FEL) proposed by LBL as part of the Combustion Dynamics Research Laboratory (CDRL) consists of a multiple-pass accelerator with superconducting cavities supplying a 55 MeV 12 mA beam to an undulator within a 24-meter optical cavity. Future options include deceleration through the same cavities for energy recovery and reducing the power in the beam dump. The electron transport system from the injector through the cavities and undulator must satisfy conditions… more
Date: July 1, 1992
Creator: Staples, J.; Edighoffer, J. & Kim, Kwang-Je.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Alternating-Phase Focusing: A Model to Study Nonlinear Dynamics

Description: We discuss a new model to study alternating-phase focusing (APF). Our approach is based on representing the accelerating electric field with a continuous phase modulated traveling wave. The resulting nonlinear equations of motion can be solved analytically to predict the regions of stable APF motion. We also identify the key parameters which adequately describe the physics of APF. The model is believed to be applicable to low-{beta} ion linacs with short independently-controlled superconducting… more
Date: January 1, 1992
Creator: Sagalovsky, L. & Delayen, J. R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Phase and amplitude stabilization of beam-loaded superconducting resonators

Description: A model has been developed to analyze the static and dynamic behavior of superconducting accelerating cavities operated in self-excited loops in the presence of phase and amplitude feedback, ponderomotive effects, and beam loading. This is an extension of an earlier analysis of the stabilization of superconducting cavities which has been the basis of the control system of several superconducting accelerators but did not include beam loading. Conditions have been derived to ensure static and dyn… more
Date: January 1, 1992
Creator: Delayen, J. R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Effects of the second harmonic cavity on rf capture and transition crossing

Description: Presented is an analysis of longitudinal beam dynamics and results of numerical simulations showing that the addition of a second harmonic cavity to the fundamental one during rf capture helps to increase the bunching factor by 23--28%, and hence reduces the space charge tune spread by an equal amount. The addition of a second harmonic cavity also helps to prevent particle losses during transition crossing by confinement of the energy spread within the bunch. A numerical simulation study shows … more
Date: January 1, 1992
Creator: Kats, J. M. & Weng, W. T.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Review of superconducting ion linacs

Description: This paper summarizes the status of the technology of superconducting (SC) linacs designed for the acceleration of ions. The emphasis is on the technical issues involved, with only brief descriptions of the numerous linacs now in operation or under construction. Recent developments of special interest are treated in more detail, and remaining technical challenges are outlined. The technology required for the acceleration of ions with velocity [beta]=1 is not discussed because it is almost the s… more
Date: January 1, 1992
Creator: Bollinger, L. M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Recent developments in thermoacoustically-driven low-frequency projectors

Description: 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: May 1, 1992
Creator: Ward, W. C. & Merrigan, M. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
Back to Top of Screen