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Options for an 11 GeV RF Beam Separator for the Jefferson Lab CEBAF Upgrade

Description: The CEBAF accelerator at Jefferson Lab has had, since first demonstration in 1996, the ability to deliver a 5-pass electron beam to experimental halls (A, B, and C) simultaneously. This capability was provided by a set of three, room temperature 499 MHz rf separators in the 5th pass beamline. The separator was two-rod, TEM mode type resonator, which has a high shunt impedance. The maximum rf power to deflect the 6 GeV beams was about 3.4kW. The 12 GeV baseline design does not preserve the capability of separating the 5th pass, 11 GeV beam for the 3 existing halls. Several options for restoring this capability, including extension of the present room temperature system or a new superconducting design in combination with magnetic systems, are under investigation and are presented.
Date: May 1, 2009
Creator: Jean Delayen, Michael Spata, Haipeng Wang
Partner: UNT Libraries Government Documents Department

COHERENT ELECTROMAGNETIC EFFECTS IN HIGH-CURRENT PARTICLE ACCELERATORS; III ELECTROMAGNETIC-COUPLING INSTABILITIES IN A COASTING BEAM

Description: The electromagnetic interaction of an intense relativistic coasting beam with itself, including the effect of a confining nonperfect vacuum tank, or a quiescent rf cavity, is investigated theoretically. It is shown that the resonances that may occur between harmonics of the particle circulation frequencies and the electromagnetic modes of the cavities can lead to a longitudinal instability of the beam. A criterion for stability of the beam against such longitudinal bunching is obtained as a restriction on the shunt impedance of the rf cavity, or the Q of the vacuum tank. This criterion contains the energy spread and intensity of the coasting beam, as well as the parameters of the accelerator. Numerical examples are given which indicate that in general the resonances with the vacuum tank will not cause instabilities, while those with an rf cavity can be prevented from causing instabilities by choosing the shunt impedance at a sufficiently low but still convenient value.
Date: August 4, 1960
Creator: Laslett, L. J.; Neil, V. Kelvin & Sessler, A. M.
Partner: UNT Libraries Government Documents Department

EVALUATION OF CONSTANT CURRENT WELD CONTROL FOR PINCH WELDING

Description: Modern weld controllers typically use current to control the weld process. SRS uses a legacy voltage control method. This task was undertaken to determine if the improvements in the weld control equipment could be implemented to provide improvements to the process control. The constant current mode of operation will reduce weld variability by about a factor of 4. The constant voltage welds were slightly hotter than the constant current welds of the same nominal current. The control mode did not appear to adversely affect the weld quality, but appropriate current ranges need to be established and a qualification methodology for both welding and shunt calibrations needs to be developed and documented.
Date: October 11, 2005
Creator: Korinko, P; STANLEY, S & HOWARD, H
Partner: UNT Libraries Government Documents Department

Experiments on HOM spectrum manipulation in a 1.3 GHz ILC SC cavity

Description: Superconducting cavities with high operating Q will be installed in the Project-X, a superconducting linac, which is under development at Fermilab. Possibility of cavity design without HOM couplers considered. Rich spectrum of the beam and large number of cavities in ProjectX linac can result to resonance excitation of some high order modes with high shunt impedance. Under scope of study of High order modes damping the manipulation with HOM spectrum in cold linac is considered. Results of detuning HOM spectrum of 1.3 GHz cavities at 2K in Horizontal Test Station of Fermilab are presented. Possible explanation of the phenomena is discussed.
Date: March 1, 2011
Creator: Khabiboulline, T.; Solyak, N.; Yakovlev, V. & /Fermilab
Partner: UNT Libraries Government Documents Department

Quench Protection for the MICE Cooling Channel Coupling Magnet

Description: This paper describes the passive quench protection system selected for the muon ionization cooling experiment (MICE) cooling channel coupling magnet. The MICE coupling magnet will employ two methods of quench protection simultaneously. The most important method of quench protection in the coupling magnet is the subdivision of the coil. Cold diodes and resistors are put across the subdivisions to reduce both the voltage to ground and the hot-spot temperature. The second method of quench protection is quench-back from the mandrel, which speeds up the spread of the normal region within the coils. Combining quench back with coil subdivision will reduce the hot spot temperature further. This paper explores the effect on the quench process of the number of coil sub-divisions, the quench propagation velocity within the magnet, and the shunt resistance.
Date: August 2, 2008
Creator: Guo, Xing Long; Xu, Feng Yu; Wang, Li; Green, Michael A.; Pan, Heng; Wu, Hong et al.
Partner: UNT Libraries Government Documents Department

A Premliminary Report on Strength of 1/2 of a 3Q120

Description: Attached please find some data taken on the dates show at MTF on a 3Q12OA magnet by utilizing a Morgan Coil for determining the strength of the quadrupole component. The probe was inserted approximately 1/2 the distance through the magnet (accuracy of longitudinal placement about .25 inch) and was rotated to record the flux change at constant current. The data are listed twice: once in time order and once sorted by current. It should be noted that these measurements were begun when the magnet had not ever been powered and the initial flux was very small. The remanent after a 400 A excitation is also available in these results. As a guide to the activity planned for each measurement, Table 3 lists with each run the title created by the measurer. these results are plotted in Figures 1-3. This magnet is marked as No.4 and to match the MTF VAX measurement system conventions, it was labeled as QGGOO4 in the data. The analysis of strength is based on a nominal probe radius determined from shop drawings. The amplitude of the quadrupole component is converted to Tesla-m/m of strength in the regular data reduction program. It is reported in the frame in which the skew quadrupole component is zero. The data is taken with the current measured at the Transductor. This is known to be an inferior method of current measurement below about 50 A. The author has not corrected the data, but a special calibration against the shunt was carried out.
Date: April 12, 1985
Creator: Brown, B.
Partner: UNT Libraries Government Documents Department

Passive modal damping with piezoelectric shunts

Description: The use of piezoelectric materials in conjunction with passive inductance-resistance-capacitance (RLC) circuits to dampen specific vibration modes is explored. The piezoelectric materials convert mechanical energy to electrical energy, which is then dissipated in the RLC circuit through joule heating. An impulse is applied to a simple cantilevered beam and by varying the inductance and resistance values, the natural oscillation frequency fcir the RLC circuit is tuned to dampen the first mode of vibration.
Date: January 1, 2001
Creator: Granier, J. J. (John J.); Haundhausen, R. J. (R. Jason) & Gaytan, G. E. (Gabriel E.)
Partner: UNT Libraries Government Documents Department

Test of a new RF Separator Structure for CEBAF

Description: A prototype of the rf separator for CEBAF has been made and successfully beam tested. This structure is a new design which has a high transverse shunt impedance together with a small transverse dimension compared to more conventional structures. Five rf separators will be used at CEBAF to allow beam from any one of the five recirculation passes to be delivered to any of the three experimental halls. This paper presents the basic design of the structure, and theoretical, rf, and beam-test results.
Date: August 1, 1992
Creator: Krycuk, Anton; Sinclair, Charles; Fugitt, Jock & Turlington, Larry
Partner: UNT Libraries Government Documents Department

Guidelines for the Calculation of the Accumulator Magnet Bus Ramps for Fermilab Experiment E835

Description: This report lists the steps that are required to calculate deceleration ramps for all relevant Accumulator devices. The ramps used for the 1996-97 fixed target run (experiment E835) are saved in files associated with ACNET console application PA1627 (PAUX RAMP DEVELOP). These ramps cannot be re-used because the Accumulator {gamma}{sub t} upgrade has significantly changed the lattice since the last time the ramps were used. Consequently, new deceleration ramps must be calculated and commissioned before the next fixed target run. The deceleration ramp for a particular device is a table that gives the sequence of set values sent to the device as the ramp is executed. The 1997 ramps consist of ramp tables for 100 devices. Appendix 1 gives a list of the devices ramped. Most of these devices will still require ramps for the next fixed target run. Future decelerations will also require ramps for the quadrupole magnet shunts that were installed as part of the {gamma}{sub t} upgrade. Additionally, ramps must be constructed for the two skew-sextupole magnets that will be installed during the summer of 1999.
Date: April 15, 1999
Creator: McGinnis, Dave; Stancari, Giulio; Werkema, Steve & /Fermilab
Partner: UNT Libraries Government Documents Department

Plutonium Finishing Plant assessment of confinement system bypass leakage

Description: The purpose of this report is to document walk-through`s of the safety class confinement systems at the Plutonium Finishing Plant (PFP). In addition this document outlines the actions taken to assess the confinement system for bypass leakage as well as establishing disposition for discovered deficiencies at the PFP.
Date: September 30, 1996
Creator: Dick, J.D.
Partner: UNT Libraries Government Documents Department

FFAGS for rapid acceleration

Description: When large transverse and longitudinal emittances are to be transported through a circular machine, extremely rapid acceleration holds the advantage that the beam becomes immune to nonlinear resonances because there is insufficient time for amplitudes to build up. Uncooled muon beams exhibit large emittances and require fast acceleration to avoid decay losses and would benefit from this style of acceleration. The approach here employs a fixed-field alternating gradient or FFAG magnet structure and a fixed frequency acceleration system. Acceptance is enhanced by the use only of linear lattice elements, and fixed-frequency rf enables the use of cavities with large shunt resistance and quality factor.
Date: September 30, 2002
Creator: Koscielniak, Carol J. Johnstone and Shane
Partner: UNT Libraries Government Documents Department

Improvements for Murrells Inlet, South Carolina: Hydraulic Model Investigation

Description: Final report of a project for the improvement and stabilization of Murrells Inlet, near Myrtle Beach, South Carolina. A model study was performed to aid in preconstruction planning and design of structural solutions to the problem of providing a stabilized channel of sufficient depth and width with provisions for sand bypassing.
Date: April 1978
Creator: Perry, Frederick C., Jr.; Seabergh, William C. & Lane, Edgar F.
Partner: UNT Libraries Government Documents Department

Design and Development of Superconducting Parallel-Bar Deflecting/Crabbing Cavities

Description: The superconducting parallel-bar cavity is a deflecting/crabbing cavity with attractive properties that is being considered for a number of applications. We present the designs of a 499 MHz deflecting cavity developed for the Jefferson Lab 12 GeV Upgrade and a 400 MHz crabbing cavity for the LHC High Luminosity Upgrade. Prototypes of these two cavities are now under development and fabrication.
Date: July 1, 2012
Creator: Payagalage Subashini Uddi De Silva, Jean Delayen
Partner: UNT Libraries Government Documents Department

COHERENT ELECTROMAGNETIC EFFECTS IN HIGH-CURRENT PARTICLE ACCELERATORS: I. INTERACTION OF A PARTICLE BEAM WITH AN EXTERNALLY DRIVEN RADIO-FREQUENCY CAVITY

Description: A calculation is made of the interaction of a beam of particles in an accelerator with the radio-frequency cavity that provides the accelerating mechanism of the machine. A Hamiltonian for synchrotron motion is employed that makes possible the simultaneous solution of Maxwell's equations and the Vlasov equation, so that a self-consistent distribution of particles in synchrotron phase space is determined. The effective voltage on the cavity due to the beam of charged particles is of the order of magnitude of the product of the total circulating current in the accelerator and the shunt impedance of the rf cavity. It has the net effect of producing a total voltage on the cavity which is both less than the applied voltage, and shifted in phase with respect to it. The increase in the stable phase angle required so the particles will remain in phase with the accelerating radio frequency is calculated. The decrease in total voltage and increase in stable phase angle result in a decrease in stable phase space available for acceleration, and convenient expressions are given for these quantities in terms of parameters of the accelerator. It is shown that the consequences of the induced voltage may be alleviated by increasing the voltage applied to the cavity.
Date: July 1, 1960
Creator: Neil, V. Kelvin & Sessler, Andrew M.
Partner: UNT Libraries Government Documents Department

Precision, 32 Channel Power Supply System

Description: A modular, multichannel current regulator system has been developed to power the low current correction and focusing magnets used for beam transport. The basic module consists of a relay rack housing four card crates with eight regulators per crate. The rack also contains a utility chassis and common power supplies. Each regulator card includes a communications microprocessor and a temperature controlled analog circuit block containing precision reference, serial DAC, shunt resistor and error amplifier. The regulators are linear, bipolar units capable of furnishing up to 10 amps at 20 volts with less than 0.01% ripple and drift.
Date: September 1, 1990
Creator: Boettcher, E.; La Mora, B.; O'Sullivan, Michael; Dobeck, Nicholas; Francis, Peter; Beaufait, Joseph et al.
Partner: UNT Libraries Government Documents Department

The SPi chip as an integrated power management device for serial powering of future HEP experiments

Description: Serial powering is one viable and very efficient way to distribute power to future high energy physics (HEP) experiments. One promising way to realize serial powering is to have a power management device on the module level that provides the necessary voltage levels and features monitoring functionality. The SPi (Serial Powering Interface) chip is such a power manager and is designed to meet the requirements imposed by current SLHC upgrade plans. It incorporates a programmable shunt regulator, two linear regulators, current mode ADCs to monitor the current distribution on the module, over-current detection, and also provides module power-down capabilities. Compared to serially powered setups that use discrete components, the SPi offers a higher level of functionality in much less real estate and is designed to be radiation tolerant. Bump bonding techniques are used for chip on board assembly providing the most reliable connection at lowest impedance. This paper gives an overview of the SPi and outlines the main building blocks of the chip. First stand alone tests are presented showing that the chip is ready for operation in serially powered setups.
Date: January 1, 2009
Creator: Trimpl, M.; Deptuch, G.; Gingu, C.; Yarema, R.; /Fermilab; Holt, R. et al.
Partner: UNT Libraries Government Documents Department

High Power, High Voltage FETs in Linear Applications: A User's Perspective

Description: The specifications of the current crop of highpower, high-voltage field-effect transistors (FETs) can lure a designer into employing them in high-voltage DC equipment. Devices with extremely low on-resistance and very high power ratings are available from several manufacturers. However, our experience shows that high-voltage, linear operation of these devices at near-continuous duty can present difficult reliability challenges at stress levels well-below their published specifications. This paper chronicles the design evolution of a 600 volt, 8 ampere shunt regulator for use with megawatt-class radio transmitters, and presents a final design that has met its reliability criteria.
Date: September 21, 2009
Creator: Greenough, N.; Fredd, E. & DePasquale, S.
Partner: UNT Libraries Government Documents Department

Quench anaylsis of MICE spectrometer superconducting solenoid

Description: MICE superconducting spectrometer solenoids fabrication and tests are in progress now. First tests of the Spectrometer Solenoid discovered some issues which could be related to the chosen passive quench protection system. Both solenoids do not have heaters and quench propagation relied on the 'quench back' effect, cold diodes, and shunt resistors. The solenoids have very large inductances and stored energy which is 100% dissipated in the cold mass during a quench. This makes their protection a challenging task. The paper presents the quench analysis of these solenoids based on 3D FEA solution of coupled transient electromagnetic and thermal problems. The simulations used the Vector Fields QUENCH code. It is shown that in some quench scenarios, the quench propagation is relatively slow and some areas can be overheated. They describe ways of improving the solenoids quench protection in order to reduce the risk of possible failure.
Date: September 1, 2011
Creator: Kashikhin, Vladimir; Bross, Alan & Prestemon, Soren
Partner: UNT Libraries Government Documents Department

High-Efficiency Resonant Cavity Quadrupole Moment Monitor

Description: Measurement of the beam quadrupole moment at several locations can be used to reconstruct the beam envelope and emittance parameters. The measurements can be performed in a non-intercepting way using a set of quadrupole-mode cavities. We present a cavity design with an optimized quadrupole moment shunt impedance. The cavity properties can be characterized using a wire test method to insure symmetry about the central axis, and alignment to nearby position sensing cavities. The design and characterization of the prototype structure is discussed.
Date: April 13, 2007
Creator: Barov, N.; Nantista, C. D.; Miller, R. H. & Kim, J. S.
Partner: UNT Libraries Government Documents Department

X-Band Traveling Wave Rf Deflector Structures

Description: Design studies on the X-Band transverse RF deflectors operating at HEM{sub ll} mode have been made for two different applications. One is for beam measurement of time-sliced emittance and slice energy spread for the upgraded LCLS project, its optimization in RF efficiency and system design are carefully considered. Another is to design an ultra-fast RF kicker in order to pick up single bunches from the bunch-train of the B-factory storage ring. The challenges are to obtain very short structure filling time with high RF group velocity and good RF efficiency with reasonable transverse shunt impedance. Its RF system will be discussed.
Date: December 18, 2008
Creator: Wang, J. W. & Tantawi, S.
Partner: UNT Libraries Government Documents Department

Implementation of Seismic Stops in Piping Systems

Description: Commonwealth Edison has submitted a request to NRC to replace the snubbers in the Reactor Coolant Bypass Line of Byron Station-Unit 2 with gapped pipe supports. The specific supports intended for use are commercial units designated ''Seismic Stops'' manufactured by Robert L. Cloud Associates, Inc. (RLCA). These devices have the physical appearance of snubbers and are essentially spring supports incorporating clearance gaps sized for the Byron Station application. Although the devices have a nonlinear stiffness characteristic, their design adequacy is demonstrated through the use of a proprietary linear elastic piping analysis code ''GAPPIPE'' developed by RLCA. The code essentially has all the capabilities of a conventional piping analysis code while including an equivalent linearization technique to process the nonlinear spring elements. Brookhaven National Laboratory (BNL) has assisted the NRC staff in its evaluation of the RLCA implementation of the equivalent Linearization technique and the GAPPIPE code. Towards this end, BNL performed a detailed review of the theoretical basis for the method, an independent evaluation of the Byron piping using the nonlinear time history capability of the ANSYS computer code and by result comparisons to the RLCA developed results, an assessment of the adequacy of the response estimates developed with GAPPIPE. Associated studies included efforts to verify the ANSYS analysis results and the development of bounding calculations for the Byron Piping using linear response spectrum methods.
Date: February 1, 1993
Creator: Bezler, P.; Simos, N. & Wang, Y.K.
Partner: UNT Libraries Government Documents Department

Waste Package Neutron Absorber, Thermal Shunt, and Fill Gas Selection Report

Description: Materials for neutron absorber, thermal shunt, and fill gas for use in the waste package were selected using a qualitative approach. For each component, selection criteria were identified; candidate materials were selected; and candidates were evaluated against these criteria. The neutron absorber materials evaluated were essentially boron-containing stainless steels. Two candidates were evaluated for the thermal shunt material. The fill gas candidates were common gases such as helium, argon, nitrogen, carbon dioxide, and dry air. Based on the performance of each candidate against the criteria, the following selections were made: Neutron absorber--Neutronit A978; Thermal shunt--Aluminum 6061 or 6063; and Fill gas--Helium.
Date: January 28, 2000
Creator: Pasupathi, V.
Partner: UNT Libraries Government Documents Department

Analysis of a grid window structure for RF cavities in a Muon cooling channel

Description: We report on the electromagnetic and thermal analysis of a grid window structure for high gradient, low frequency RF cavities. Windows may be utilized to close the beam iris and increase shunt impedance of closed-cell RF cavities. This work complements previous work presented for windows made of solid beryllium foil. An electromagnetic and thermal analysis of the thin wall tubes in a grid pattern was conducted using both MAFIA4 and ANSYS finite element analyses. The results from both codes agreed well for a variety of grid configurations and spacing. The grid configuration where the crossing tubes touched was found to have acceptable E-Fields and H-Fields performance. The thermal profiles for the grid will also be shown to determine a viable cooling profile.
Date: May 1, 2003
Creator: Ladran, A.; Li, D.; Moretti, A.; Rimmer, R.; Staples, J.; Virostek, S. et al.
Partner: UNT Libraries Government Documents Department

SPi User Manual V0.1

Description: This document describes the Serial Powering Interface (SPi) ASIC. SPi is a general purpose ASIC prototype designed for use in serial powering of silicon detector instrumentation. This description is written as a user manual to aid application, not as a design description. SPi is a generic custom ASIC, manufactured in 0.25 {mu}m CMOS by TSMC, to interface between a constant current source and silicon detector read-out chips. There is no SEU (single event upset) protection, but most (not all) components are radiation tolerant design. An operating voltage of 1.2 to 2.5 volts and other design features make the IC suitable for a variety of serial powering architectures and ROICs. It should be noted that the device is likely to be a prototype for demonstration rather than a product for inclusion in a detector. The next design(s), SPin, are likely to be designed for a specific application (eg SLHC). The component includes: (1) Seven bi-directional LVDS-like buffers for high data rate links to/from the read-out chips. These are AC coupled (series capacitor) off-chip for DC level conversion; (2) A programmable internal programmable shunt regulator to provide a defined voltage to readout chips when linked in a serial powering chain; (3) A programmable internal shunt regulator control circuit for external transistor control; (4) Shunt current measurement (for internal shunt regulator); (5) A programmable internal shunt regulator current alarm; and (6) Two programmable linear regulators.
Date: May 1, 2011
Creator: Trimpl, M.; Yarema, R.; /Fermilab; Newcomer, M.; Dressnandt, N.; U., /Pennsylvania et al.
Partner: UNT Libraries Government Documents Department