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Field emission and rf breakdown in copper linac structures

Description: This paper presents a status report on rf field emission and high-gradient breakdown studies in linac structures at SLAC. The motivation behind these studies, begun in 1984, is to determine the maximum accelerating field gradients that could be used safely in future e/sup /plus minus// colliders, to contribute to the basic understanding of the rf breakdown mechanism, and to discover if special surface treatments might make it possible to shorten the time needed for rf processing and to supersede the field limits presently reachable in room temperature copper structures. Both theoretical ideas and experimental results are discussed. 8 refs., 3 figs., 1 tab.
Date: August 1, 1989
Creator: Loew, G.A. & Wang, J.W.
Partner: UNT Libraries Government Documents Department

Scintillating fiber ribbon --- tungsten calorimeter

Description: We describe an ultra-high density scintillating fiber and tungsten calorimeter used as an active beam-dump for electrons. Data showing the calorimeter response to electrons with momenta between 50 and 350 GeV/c are presented. 9 figs.
Date: July 14, 1989
Creator: Bross, A.; Crisler, M.; Kross, B. & Wrbanek, J.
Partner: UNT Libraries Government Documents Department

Construction of a Fermilab superferric test magnet

Description: This technical memo documents the construction of a cold iron superconducting test magnet. The superferric magnet design was based on a concept sketch provided by Bob Wilson. Construction and dunk testing of the magnet in a liquid helium dewar took place in a time period of less than one week. The magnet operated successfully to its design field of 2 Tesla with no training.
Date: July 1, 1982
Creator: Heim, J.; Hinterberger, H. & Jagger, J.
Partner: UNT Libraries Government Documents Department

A design chart for long vacuum pipes and shells

Description: This paper presents a design chart to aid designers in the selection of a wall thickness for long cylindrical shells having atmospheric pressure outside the shell and a pressure less than atmospheric inside the shell. The chart indicates a conservative value for the minimum wall thickness for a given shell diameter and material when the shell is completely evacuated.
Date: July 22, 1986
Creator: Krempetz, K.; Grimson, J. & Kelly, P.
Partner: UNT Libraries Government Documents Department

Performance testing of super Fe magnet

Description: A summary is given of the data obtained during the testing of a proof of principle iron-dominated low field and cost, high efficiency dipole. The magnet was tested for performance with the design field of 2.0T.
Date: June 30, 1982
Creator: McInturff, A.D.
Partner: UNT Libraries Government Documents Department

Transient high-field behavior of niobium superconducting cavities

Description: Tests have been performed on the breakdown behavior of a TM/sub 010/ mode, S-band niobium cavity at low temperatures. Unloaded Q's of 9 x 10/sup 7/ at 4.2 K and of 7 x 10/sup 9/ at 1.35 K were measured during several tests performed using pulses long enough for the cavity to reach steady state. The breakdown field at 1.35 K was increased from 15 to 20 MV/m by processing the cavity at room temperature using 1 MW, 2.5 ..mu..s pulses. The response of the cavity at 4.2 K to 1 MW, 2.5..mu..s pulses was also tested in several cool-downs. In these tests the cavity was heavily overcoupled to lower its time constant to a value of 0.80 times the RF pulse length of 2.5 ..mu..s. This condition maximizes the energy transfer from the klystron source to the cavity. Measurements made during these experiments clearly indicated that fields of about 50 MV/m were being reached in the cavity without breakdown.
Date: March 1, 1983
Creator: Campisi, I.E.; Farkas, Z.D.; Deruyter, H. & Hogg, H.A.
Partner: UNT Libraries Government Documents Department

Water cooled metal optics for the Advanced Light Source

Description: The program for providing water cooled metal optics for the Advanced Light Source at Berkeley is reviewed with respect to fabrication and metrology of the surfaces. Materials choices, surface figure and smoothness specifications, and metrology systems for measuring the plated metal surfaces are discussed. Results from prototype mirrors and grating blanks will be presented, which show exceptionally low microroughness and mid-period error. We will briefly describe out improved version of the Long Trace Profiler, and its importance to out metrology program. We have completely redesigned the mechanical, optical and computational parts of the profiler system with the cooperation of Peter Takacs of Brookhaven, Continental Optical, and Baker Manufacturing. Most important is that one of our profilers is in use at the vendor to allow testing during fabrication. Metrology from the first water cooled mirror for an ALS beamline is presented as an example. The preplating processing and grinding and polishing were done by Tucson Optical. We will show significantly better surface microroughness on electroless nickel, over large areas, than has been reported previously.
Date: October 28, 1991
Creator: McKinney, W.R.; Irick, S.C. (Lawrence Berkeley Lab., CA (United States)) & Lunt, D.L.J. (Tucson Optical Research Corp., AZ (United States))
Partner: UNT Libraries Government Documents Department

Fast excitation variable period wiggler

Description: The design of an easily stackable, variable period length, fast excitation driven wiggler, making use of geometrically alternating substacks of Vanadium Permandur ferromagnetic laminations, interspaced with conductive, non magnetic, laminations which act as eddy current induced field reflectors,'' is discussed and experimental results obtained with short wiggler models are presented.
Date: January 1, 1991
Creator: van Steenbergen, A.; Gallardo, J.; Romano, T. & Woodle, M.
Partner: UNT Libraries Government Documents Department

A water-cooled mirror system for synchrotron radiation

Description: This paper describes the design and performance of a directly-cooled soft x-ray mirror system which has been developed at Lawrence Berkeley Laboratory for synchrotron radiation beam lines in which mirror thermal distortion must be minimized for acceptable optical performance. Two similar mirror systems are being built: the first mirror has been installed and operated at the National Synchrotron Light Source on the X-17T mini-undulator beam line and will be moved to the permanent X-1 beam line when a new, more powerful undulator is installed there. The second system is being built for installation at the Stanford Synchrotron Radiation Laboratory on Beam Line VI, where the total absorbed power on the mirror may be as high as 2400 W with peak absorbed power density of 520 W/cm/sup 2/. Direct cooling by convection is achieved using internal water channels in a brazed, dispersion-strengthened copper and OFHC copper substrate with a polished electroless-nickel surface. A simple kinematic linkage and flexural pivot mounting provide for mirror positioning about two rotational axes that coincide with the optical surface. Surface figure metrology, optical configurations, and tolerancing are also discussed. 11 refs., 8 figs.
Date: June 1, 1987
Creator: DiGennaro, R.; Gee, B.; Guigli, J.; Hogrefe, H.; Howells, M. & Rarback, H.
Partner: UNT Libraries Government Documents Department

A simple cantilevered mirror for focussing synchrotron radiation

Description: A large cantilevered mirror was constructed to focus the vertical divergence from a synchrotron radiation source. The advantages of this mirror are its compactness, simple bending device, simplicity of construction, and good thermal contact to structures outside the vacuum. The central portion of the mirror is supported with variable loading springs to reduce gravitational sag. The figure and thermal stability of the mirror have proven to be excellent, though the focusing is limited by the roughness of the mirror-surface. This paper describes the design, construction, and performance of the mirror.
Date: June 21, 1987
Creator: Ice, G.E. & Sparks, C.J.
Partner: UNT Libraries Government Documents Department

The LANSCE (Los Alamos Neutron Scattering Center) target system

Description: During the summer of 1985, we replaced the WNR T-shaped target/moderator scheme with the LANSCE split-target/flux-trap-moderator design. The intent of this 'LANSCE upgrade' was to increase (to 12) the number of neutron beam lines serviced simultaneously, and to enhance the target area shielding and target system to accept 200 ..mu..A of 800-MeV protons. The four LANSCE moderators consist of three (chilled) water moderators, and a liquid hydrogen (20 K) moderator. The LANSCE target is machinable tungsten.
Date: September 22, 1986
Creator: Russell, G.J.; Robinson, H.; Legate, G.L.; Woods, R.; Whitaker, E.R.; Bridge, A. et al.
Partner: UNT Libraries Government Documents Department

Evaluation of target purity using various vacuum systems

Description: Gold targets were prepared under various conditions using both a cryopump and a conventional diffusion pump evaporator system. Measurements were made at the Argonne Tandem Accelerator system to determine the purity of these targets.
Date: January 1, 1984
Creator: Thomas, G.E.; Rehm, K.E. & Klimczak, G.W.
Partner: UNT Libraries Government Documents Department

In-situ shearing interferometry of National Synchrotron Light Source mirrors

Description: In situ mirror distortion measurements were made with a lateral shearing interferometer on three mirrors in beam line X17T at the National Syn203hrotron Light Source. Lateral shearing interference is insensitive to vibrational motion in five of the six degrees of freedom, so it is well-suited for investigations in the synchrotron radiation (SR) environment. No distortion was seen in an uncooled silicon carbide mirror and in a colled copper alloy mirror on X17TB, but a change in the radius of an uncooled electroless nickel-plated aluminium cylinder mirror of about 6.2% was observed on X17TA. Angular vibrations in the 2 to 3 arc second range were easily observed on one of the beam lines, as was an overall mirror rotation in the arc second range.
Date: January 1, 1987
Creator: Qian, S.N.; Rarback, H.; Shu, D. & Takacs, P.Z.
Partner: UNT Libraries Government Documents Department

Improved copper septum magnet design

Description: A copper septum magnet of improved design has been developed to replace the existing F5 septum deflector in the slow-extraction channel at the Brookhaven National Laboratory AGS. The new magnet has several novel design features such as a solid rather than laminated core, a ball bearing suspended septum and a radiation resistant quick disconnect system.
Date: January 1, 1981
Creator: Rodger, E S & Weisberg, H L
Partner: UNT Libraries Government Documents Department

Magnetic properties of the iron laminations for CBA magnets

Description: The required magnetic properties of the iron for CBA dipoles are for the most part the same as those for conventional accelerators, namely: low coercive force, high permeability at both low and high inductions, and high saturation induction. There are two main differences in the CBA application, (1) the iron is at 3.8/sup 0/K, and (2) the magnetic field in the iron can go as high as 6 Tesla, which is well above saturation. Measurements of the magnetization curves for CBA iron laminations at 300/sup 0/K and 4.2/sup 0/K are presented. The data are analyzed in terms of a simple model in which the variation in saturation induction can be separated from the low field permeability variation. Tolerances on coercive force, permeability, and saturation induction are discussed.
Date: January 1, 1983
Creator: Tannenbaum, M.J.; Ghosh, A.K.; Robins, K.E. & Sampson, W.B.
Partner: UNT Libraries Government Documents Department

Niobium resonator development for high-brightness ion beam acceleration

Description: Two niobium resonant cavities for high-brightness ion beam acceleration have been constructed and tested. The first was based on a coaxial quarter-wave geometry and was optimized for phase velocity {beta}{sub o} = 0.15. This cavity, which resonates at 400 MHz in the fundamental mode, operated at an average (wall-to-wall) accelerating gradient of 12.9 MV/m under continuous-wave (cw) fields. At this gradient, a cavity Q of 1.4 {times} 10{sup 8} was measured. The second was based on a coaxial half-wave geometry and was optimized for {beta}{sub o} = 0.12. This cavity, which resonates at 355 MHz in the fundamental mode, operated at an average accelerating gradient of 18.0 MV/m under cw fields. This is the highest average accelerating gradient achieved to date in low-velocity structures designed for cw operation. At this gradient, a cavity Q of 1.2 {times} 10{sup 8} was measured.
Date: January 1, 1990
Creator: Delayen, J.R.; Bohn, C.L. & Roche, C.T.
Partner: UNT Libraries Government Documents Department

Progress report on high-gradient RF studies in copper accelerator structures

Description: This paper is a progress report on studies carried out at the Stanford Linear Accelerator Center to understand the behavior of copper accelerator structures under extremely high RF fields. Such structures are being designed for future electron-positron linear colliders. Recent studies include field emission and breakdown experiments with an S-band slotted-disk structure, a single demountable S-band cavity and a short X-band structure which has not yet been tested. The demountable cavity was built specifically to examine the effects of copper quality, surface conditioning, gaseous exposures, and surface damage. Results to date and recent theoretical conjectures are discussed.
Date: September 1, 1990
Creator: Loew, G.A. & Wang, J.W.
Partner: UNT Libraries Government Documents Department

Progress in the chemistry of chromium(V) doping agents used in polarized target materials

Description: We wish to report progress in two areas of the chromium (V)-based doping agents: Two commonly used chromium (V) complexes, I and II, have been synthesized in perdeuterated form (i.e., all hydrogens replaced by deuterium). They are sodium bis(2-ethyl-2-deuteroxy-butyrato)oxochromate(V)monodeuterate, IV, (acronym EDBA-Cr(V)), and sodium bis(2-deuteroxy-2-methylpropionato)oxochromate(V), III, (acronym DMPA-Cr(V)). A synthetic route leading to the preparation of stable, chromium(III)-free solutions of chromium(V) in diols (1,2-ethanediol/ethylene glycol/and 1,2-propanediol/propylene glycol/) has been outlined.
Date: January 1, 1990
Creator: Krumpolc, M. (Illinois Univ., Chicago, IL (USA)); Hill, D. (Argonne National Lab., IL (USA)) & Struhrmann, H.B. (Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany, F.R.). Hamburger Synchrotronstrahlungslabor)
Partner: UNT Libraries Government Documents Department

Enhanced heat transfer with metal wool filled tubes

Description: The Advanced Photon Source (APS) to be constructed at Argonne National Laboratory (ANL) utilizes magnetic devices which generate x-ray beams with very intense heat flux levels. The flux levels encountered can be one or two orders of magnitude higher than those commonly found in nuclear reactors or fusion devices. The beam line elements and optics on such beams pose significant challenge to the researchers and designers to keep them cooled at acceptable levels of surface temperature and/or temperature gradients. Therefore, methods and techniques achieving heat removal enhancement are constantly sought. One such technique suggested and considered is the use of conductive metal wool filled tubes where the filter is brazed to the tube walls. A comparative investigation of the conventionally achievable heat transfer coefficient h'' with water and the wall conductance of a heavy wall copper tube reveals that major resistance is on the coolant side. Therefore, there exists a significant opportunity to improve heat transfer in the tubes by enhancement of the coolant side. To this end a variety of copper wool filled tubes as well as a commercially available enhanced copper tube were subjected to laboratory tests with water and conventional heating to assess the resulting heat transfer improvement. Design improvements using enhanced cooling are discussed in terms of structural weight, controls, grazing angles, the operational reliability. 9 refs., 11 figs., 5 tabs.
Date: August 1, 1990
Creator: Kuzay, T.M.; Collins, J.T.; Khounsary, A.M. (Argonne National Lab., IL (USA)) & Morales, G. (Argonne National Lab., IL (USA) Texas Univ., El Paso, TX (USA))
Partner: UNT Libraries Government Documents Department

Iron saturation control in RHIC dipole magnets

Description: The Relativistic Heavy Ion Collider (RHIC) will require 360 dipoles of 80 mm bore. This paper discusses the field perturbations produced by the saturation of the yoke iron. Changes have been made to the yoke to reduce these perturbations, in particular, decapole < 10{sup {minus}4}. Measurements and calculations for 6 series of dipole magnets are presented. 2 refs., 2 figs., 1 tab.
Date: January 1, 1991
Creator: Thompson, P.A.; Gupta, R.C.; Kahn, S.A.; Hahn, H.; Morgan, G.H.; Wanderer, P.J. et al.
Partner: UNT Libraries Government Documents Department

A high repetition rate beam profile monitor

Description: A high repetition rate beam profile monitor is needed to measure the momentum distribution of each bunch in a 200 bunch train at the Brookhaven Accelerator Test Facility. We have designed a monitor using secondary emission from a microstrip delay line. The delay line converts position information into discrete time delays synchronous with the sampling rate of a fast transient digitizer. We present the results of initial electrical testing here.
Date: January 1, 1991
Creator: Rogers, J.T.; Warren, J.B. (Brookhaven National Lab., Upton, NY (United States)) & Gray, A. (State Univ. of New York, Stony Brook, NY (United States). Dept. of Physics)
Partner: UNT Libraries Government Documents Department

Iron dominated magnets

Description: These two lectures on iron dominated magnets are meant for the student of accelerator science and contain general treatments of the subjects design and construction. The material is arranged in the categories: General Concepts and Cost Considerations, Profile Configuration and Harmonics, Magnetic Measurements, a few examples of ''special magnets'' and Materials and Practices. Extensive literature is provided.
Date: July 1, 1985
Creator: Fischer, G.E.
Partner: UNT Libraries Government Documents Department

Evaporation techniques for preparing rare-earth targets used in heavy-ion nuclear physics

Description: The preparation techniques for producing nuclear targets of the rare-earth isotopes depends greatly upon the physical properties of the particular rare-earth element. In most cases the isotope is supplied in the oxide form which then requires reduction to obtain the metal. Collection efficiencies will be discussed as this is of vital importance when considering the price and availability of the isotopic material. 12 refs, 2 figs., 4 tabs.
Date: January 1, 1990
Creator: Greene, J.P. & Thomas, G.E.
Partner: UNT Libraries Government Documents Department

Development of manufacturing methods for 50-cm diameter neutron source targets for RTNS-II

Description: RTNS-II is an accelerator driven neutron source. It was attempted to produce a larger version of the current accelerator target but experienced problems in diffusion bonding and thermal stability of the copper alloy used for target fabrication. The causes of these problems were identified, and a new technique (electroforming) was demonstrated for fabricating targets.
Date: June 1, 1981
Creator: Logan, C.M.; Dini, J.W.; Ludemann, W.D.; Schumacher, B.J.; Dalder, E.N.C.; Kelley, W.K. et al.
Partner: UNT Libraries Government Documents Department