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Sonic helium detectors in the Fermilab Tevatron

Description: In the Fermilab Tevatron cryogenic system there are many remotely located low-pressure plate relief valves that must vent large volumes of cold helium gas when magnet quenches occur. These valves can occasionally stick open or not reseat completely, resulting in a large helium loss. As such, the need exists for a detector to monitor the relief valve's discharge area for the presence of helium. Due to the quantity needed, cost is an important factor. A unit has been developed and built for this purpose that is quite inexpensive. Its operating principle is based on the speed of sound, where two closely matched tubes operate at their acoustic resonant frequency. When helium is introduced into one of these tubes, the resulting difference in acoustic time of flight is used to trigger an alarm. At present, there are 39 of these units installed and operating in the Tevatron. They have detected many minor and major helium leaks, and have also been found useful in detecting a rise in the helium background in the enclosed refrigerator buildings. This paper covers the construction, usage and operational experience gained with these units over the last several years.
Date: January 1, 2006
Creator: Bossert, R.J.
Partner: UNT Libraries Government Documents Department

A technique for epoxy free winding and assembly of cos. theta. coils for accelerator magnets

Description: Traditional methods of magnet construction (wet winding) use molded coil subassemblies bonded together with epoxy impregnated fiberglass tape. This is a highly labor intensive process involving redundant operations for each of the four coils. The epoxy free winding technique (dry winding) eliminates the epoxy curing steps and also allows all four coils to be wound on 3 common winding mandrel, thereby reducing winding stations and handling. The tooling required for dry winding is a radical departure from existing technology imposing new mechanical problems. A number of 64 cm long 5 cm aperture SSC Design B'' magnets have been produced at Fermilab utilizing dry winding techniques. Discussed is the specialized tooling created to accomplish dry winding as well as new winding and assembly procedures required. Also discussed are mechanical problems encountered and their solutions. Based on experience gained, dry winding can be a viable lower cost alternative to traditional coil fabrication techniques.
Date: September 30, 1986
Creator: Carson, J.A. & Bossert, R.
Partner: UNT Libraries Government Documents Department

Analysis of magnetic measurements of short model quadrupoles for the LHC low-b insertions

Description: The first two short models of the MQXB quadrupole magnets for the LHC interaction regions have been built and tested at Fermilab. In this paper we present the magnetic field measurement results and compare them with expectations based on as-built dimensional parameters and with a preliminary table of field quality requirements.
Date: July 1, 1998
Creator: Bossert, R. & others, and
Partner: UNT Libraries Government Documents Department

Mechanical design of CDF end plug optical system

Description: The CDF End Plug at Fermilab is being upgraded to optical fiber technology. Fibers must extend from individual EM, Hadron and Shower Max pans within the plug to photomultiplier tubes mounted on the plug face. The entire system involves the organized splicing, coupling and routing of over 24000 optical fibers and 2000 source tubes per plug. Routing paths, methods of coupling and attachments of the fibers to the pans and plug are shown.
Date: August 1, 1995
Creator: Bossert, R.; Dixon, R. & Ewald, K.
Partner: UNT Libraries Government Documents Department

Mechanical support of superconducting coils

Description: Cold iron magnets use the iron yoke and skin for mechanical support of the collared coil assembly. A variety of designs, including horizontally and vertically split yokes, collarless'' magnets and conductor block geometries, have been considered for use with collared coils. This note qualitatively compares the support mechanisms by estimating the amount of coil overcompression'' necessary for the magnet to achieve the same mechanical condition in the cold, powdered state. These designs inspect magnet limitations by suggesting means to reduce the peak coil compressive load, allowing higher central magnetic fields to be reached.
Date: July 1, 1990
Creator: Bossert, R.C. & Kerby, J.S.
Partner: UNT Libraries Government Documents Department

Measurements of SCRF cavity dynamic heat load in horizontal test system

Description: The Horizontal Test System (HTS) at Fermilab is currently testing fully assembled, dressed superconducting radio frequency (SCRF) cavities. These cavities are cooled in a bath of superfluid helium at 1.8K. Dissipated RF power from the cavities is a dynamic heat load on the cryogenic system. The magnitude of heat flux from these cavities into the helium is also an important variable for understanding cavity performance. Methods and hardware used to measure this dynamic heat load are presented. Results are presented from several cavity tests and testing accuracy is discussed.
Date: November 1, 2009
Creator: DeGraff, B.D.; Bossert, R.J.; Pei, L.; Soyars, W.M. & /Fermilab
Partner: UNT Libraries Government Documents Department

Tests of insulation systems for Nb3Sn wind and react coils

Description: Tests were performed to assess the viability of several cable insulation systems for use in Nb{sub 3}Sn accelerator magnets. Insulated stacks of cables were subjected to reaction cycles commonly used for Nb{sub 3}Sn coils. After reaction and epoxy impregnation, current leakage between turns was measured at pressures up to 180 MPa and turn-to-turn potentials up to 500V. Systems consisting of S-2 glass, ceramic fiber, and E-glass were tested. Several methods of applying the insulation were incorporated, including sleeves and various spiral wrapped configurations. Methods of sample preparation and testing are described and results are reported.
Date: July 1, 2007
Creator: Bossert, R.; Ambrosio, G; Andreev, N.; Whitson, G.; Zlobin, A. & /Fermilab
Partner: UNT Libraries Government Documents Department

Critical speed measurements in the Tevatron cold compressors

Description: The Fermilab Tevatron cryogenic system utilizes high-speed centrifugal cold compressors, manufactured by Ishikawajima-Harima Heavy Industries Co. Ltd. (IHI), for high energy operations. Nominal operating range for these compressors is 43,000 to 85,000 rpm. Past foil bearing failures prompted investigation to determine if critical speeds for operating compressors fall within operating range. Data acquisition hardware and software settings will be discussed for measuring liftoff, first critical and second critical speeds. Several tests provided comparisons between an optical displacement probe and accelerometer measurements. Vibration data and analysis of the 20 Tevatron ring cold compressors will be presented.
Date: January 1, 2006
Creator: DeGraff, B.; Bossert, R.; Martinez, A.; Soyars, W.M. & /Fermilab
Partner: UNT Libraries Government Documents Department

Development of a high gradient quadrupole for the LHC Interaction Regions

Description: A collaboration of Fermilab, Lawrence Berkeley National Laboratory and Brookhaven National Laboratory is engaged in the design of a high gradient quadrupole suitable for use in the LHC interaction regions. The cold iron design incorporates a two-layer, cos(2{theta}) coil geometry with a 70 mm aperture operating in superfluid helium. This paper summarizes the progress on a magnetic, mechanical and thermal design that meets the requirements of maximum gradient above 250 T/m, high field quality and provision for adequate cooling in a high radiation environment.
Date: April 1, 1997
Creator: Bossert, R.; Feher, S. & Gourlay, S.A.
Partner: UNT Libraries Government Documents Department

Mechanical design and analysis of the 2D cross-section of the SSC collider dipole magnet

Description: This paper describes the mechanical design of the two dimensional cross-section of the base-line collider dipole magnet for the Superconducting Super Collider. The components described here are the collar laminations, the tapered keys that lock the upper and lower collars, the yoke laminations, the cold mass shell. We describe in detail the shape of the outer surface of the collars which defines the yoke-collar interface, and the shape of the collar interior, which defines the conductor placement. Other features of the collar and yoke will be described in somewhat less detail. 20 refs., 12 figs. , 6 tabs.
Date: May 1, 1991
Creator: Strait, J.; Kerby, J.; Bossert, R. & Carson, J.
Partner: UNT Libraries Government Documents Department

SSC (Superconducting Super Collider) dipole coil production tooling

Description: Superconducting Super Collider dipole coils must be produced to high precision to ensure uniform prestress and even conductor distribution within the collared coil assembly. Tooling is being prepared at Fermilab for the production of high precision 1M and 16.6M SSC dipole coils suitable for mass production. The design and construction methods builds on the Tevatron tooling and production experience. Details of the design and construction methods and measured coil uniformity of 1M coils will be presented. 4 refs., 10 figs.
Date: March 1, 1989
Creator: Carson, J.A.; Barczak, E.J.; Bossert, R.C.; Brandt, J.S. & Smith, G.A.
Partner: UNT Libraries Government Documents Department

End designs for superconducting magnets

Description: New accelerators such as the Tevatron Upgrade frequently require higher magnetic fields that have been conventionally used in superconducting magnets. Modern magnet designs often have a smaller bore diameter and wider cable than the early (e.g., Tevatron) superconducting coils and are consequently harder to wind. These developments make consideration of end winding more important. End parts must be made to confine the conductors to a consistent shape. This shape must be defined and described to both the parts manufacturers and those analyzing the magnetic field. Internal stresses in the cable must be minimized. It has therefore become necessary to reevaluate the methods used to determine the configuration of a magnetic end. This note describes those methods and attempts to apply them to possible cross sections for high field dipoles. The original Tevatron dipole end configuration is reviewed for reference. 3 refs., 10 figs., 1 tab.
Date: October 1, 1991
Creator: Bossert, R.C.; Cook, J.M. & Brandt, J.S.
Partner: UNT Libraries Government Documents Department

End designs for superconducting magnets

Description: New accelerators such as the Tevatron Upgrade frequently require higher magnetic fields that have been conventionally used in superconducting magnets. Modern magnet designs often have a smaller bore diameter and wider cable than the early (e.g., Tevatron) superconducting coils and are consequently harder to wind. These developments make consideration of end winding more important. End parts must be made to confine the conductors to a consistent shape. This shape must be defined and described to both the parts manufacturers and those analyzing the magnetic field. Internal stresses in the cable must be minimized. It has therefore become necessary to reevaluate the methods used to determine the configuration of a magnetic end. This note describes those methods and attempts to apply them to possible cross sections for high field dipoles. The original Tevatron dipole end configuration is reviewed for reference. 3 refs., 10 figs., 1 tab.
Date: October 1, 1991
Creator: Bossert, R. C.; Cook, J. M. & Brandt, J. S.
Partner: UNT Libraries Government Documents Department

Quench margin measurement in Nb3Sn quadrupole magnet

Description: One of the possible practical applications of the Nb{sub 3}Sn accelerator magnets is the LHC luminosity upgrade that involves replacing the present NbTi focusing quadrupoles in two high-luminosity interaction regions (IR). The IR magnets are exposed to strong radiation from the interaction point that requires a detailed investigation of the magnet operating margins under the expected radiation-induced heat depositions. This paper presents the results of simulation and measurement of quench limits and temperature margins for a Nb{sub 3}Sn model magnet using a special midplane strip heater.
Date: August 1, 2008
Creator: Kashikhin, V.V.; Bossert, R.; Chlachidze, G.; Lamm, M.; Novitski, I.; Zlobin, A.V. et al.
Partner: UNT Libraries Government Documents Department

Low temperature quench performance of Fermilab Low-{Beta} insertion quadrupoles

Description: The recently revived superconducting magnet program at Fermilab is currently focused on the development of high gradient quadrupoles for possible use in the Large Hadron Collider (LHC) interaction regions at CERN. In order to provide input for the new quadrupole design which will operate in superfluid helium, we have tested a Fermilab Tevatron low-{beta} quadrupole cold mass and compared its low temperature performance to a newly assembled heavily instrumented version which was mechanically modified to take advantage of the gain in critical current.
Date: April 1, 1997
Creator: Bossert, R.; Lietzke, A.; McInturff, A.D.; Scanlan, R. & Collaboration, LHC
Partner: UNT Libraries Government Documents Department

5cm aperture dipole studies

Description: The results obtained during the evolution of the design, construction, and testing program of the design ''B'' dipole are presented here. Design ''B'' is one of the original three competing designs for the Superconducting Super Collider ''SSC'' arc dipoles. The final design parameters were as follows: air cored (less than a few percent of the magnetic field derived from any iron present), aluminum collared, two layered winding, 5.5T maximum operating field, and a 5 cm cold aperture. There have been fourteen 64 cm long 5 cm aperture model dipoles cold tested (at 4.3K and less) in this program so far. There was a half length full size (6m) mechanical analog (M-10) built and tested to check the cryostat's mechanical design under ramping and quench conditions. Several deviations from the ''Tevatron'' dipole fabrication technique were incorporated, for example the use of aluminum collars instead of stainless steel. The winding technique variations explored were ''dry welding,'' a technique with the cable covered with Kapton insulation only and ''wet winding'' where the Kapton was covered with a light coat of ''B'' stage epoxy. Test data include quench currents, field quality (Fourier multipole co-efficients), coil magnetization, conductor current performance, and coil loading. Quench current, loss per cycle, and harmonics were measured as a function of the magnitude and rate of change of the magnetic field, and helium bath temperature.
Date: September 30, 1986
Creator: McInturff, A.D.; Bossert, R.; Carson, J.; Fisk, H.E.; Hanft, R.; Kuchnir, M. et al.
Partner: UNT Libraries Government Documents Department

SSC (Superconducting Super Collider) magnet mechanical interconnections

Description: Installation of superconducting accelerator dipole and quadrupole magnets and spool pieces in the SSC tunnel requires the interconnection of the cryostats. The connections are both of an electrical and mechanical nature. The details of the mechanical connections are presented. The connections include piping, thermal shields and insulation. There are seven piping systems to be connected. These systems must carry cryogenic fluids at various pressures or maintain vacuum and must be consistently leak tight. The interconnection region must be able to expand and contract as magnets change in length while cooling and warming. The heat leak characteristics of the interconnection region must be comparable to that of the body of the magnet. Rapid assembly and disassembly is required. The magnet cryostat development program is discussed. Results of quality control testing are reported. Results of making full scale interconnections under magnet test situations are reviewed. 11 figs., 4 tabs.
Date: March 1, 1989
Creator: Bossert, R.C.; Niemann, R.C.; Carson, J.A.; Ramstein, W.L.; Reynolds, M.P. & Engler, N.H.
Partner: UNT Libraries Government Documents Department

Analytical solutions to SSC coil end design

Description: As part of the SCC magnet effort, Fermilab will build and test a series of one meter model SSC magnets. The coils in these magnets will be constructed with several different end configurations. These end designs must satisfy both mechanical and magnetic criteria. Only the mechanical problem will be addressed. Solutions will attempt to minimize stresses and provide internal support for the cable. Different end designs will be compared in an attempt to determine which is most appropriate for the SSC dipole. The mathematics required to create each end configuration will be described. The computer aided design, programming and machine technology needed to make the parts will be reviewed. 2 refs., 10 figs.
Date: March 1, 1989
Creator: Bossert, R.C.; Brandt, J.S.; Carson, J.A.; Fulton, H.J.; Lee, G.C. & Cook, J.M.
Partner: UNT Libraries Government Documents Department

Dynamic PID loop control

Description: The Horizontal Test Stand (HTS) SRF Cavity and Cryomodule 1 (CM1) of eight 9-cell, 1.3GHz SRF cavities are operating at Fermilab. For the cryogenic control system, how to hold liquid level constant in the cryostat by regulation of its Joule-Thompson JT-valve is very important after cryostat cool down to 2.0 K. The 72-cell cryostat liquid level response generally takes a long time delay after regulating its JT-valve; therefore, typical PID control loop should result in some cryostat parameter oscillations. This paper presents a type of PID parameter self-optimal and Time-Delay control method used to reduce cryogenic system parameters oscillation.
Date: June 1, 2011
Creator: Pei, L.; Klebaner, A.; Theilacker, J.; Soyars, W.; Martinez, A.; Bossert, R. et al.
Partner: UNT Libraries Government Documents Department

Performance of Nb3Sn quadrupole magnets under localized thermal load

Description: This paper describes the results of design and analyses performed on 120-mm Nb{sub 3}Sn and NbTi quadrupole magnets with parameters relevant for the LHC IR upgrade. A realistic radiation heat load is evaluated in a wide luminosity range and translated into the magnet quench performance. The simulation results are supported by thermal measurements on a 90-mm Nb{sub 3}Sn quadrupole coil.
Date: June 1, 2009
Creator: Kashikhin, V.V.; Bossert, r.; Chlachidze, G.; Lamm, M.; Mokhov, N.V.; Novitski, I. et al.
Partner: UNT Libraries Government Documents Department

Study of effects of deformation in Nb3Sn multifilamentary strands

Description: In the process that leads a flawless Nb{sub 3}Sn round strand to become part of a Rutherford cable first, and of a coil next, the same cabling process affects strands of different kinds in different ways, from filament shearing to subelement merging to composite decoupling. Due to plastic deformation, after cabling the filament size distributions in a strand usually change. The average filament size typically increases, as does the width of the distribution. This is consistent with the low field transport current of strands in cables being typically lower and less reproducible than for round strands [1]. To better understand the role of filament size in instabilities and to simulate cabling deformations, strands to be used in cables can be tested by rolling them down to decreasing sizes to cover an ample range of relative deformations. A procedure is herein proposed that uses both microscopic analysis and macroscopic measurements of material properties to study the effects of deformation.
Date: August 1, 2006
Creator: Turrioni, D.; Barzi, E.; Bossert, R.; Kashikhin, V.V.; /Fermilab; Kikuchi, A. et al.
Partner: UNT Libraries Government Documents Department