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Cryogenic studies of rf accelerating structures, vintage 1978

Description: Cryogenically cooled rf cavity studies were undertaken at Los Alamos in 1978 to test the effectiveness of reduced temperature on the Q-enhancement of 450-MHz drift-tube linac structures. A complete facility was set up to do high power tests, not only at liquid nitrogen (LN/sub 2/) temperature but with liquid hydrogen (LH/sub 2/) as well. The cavity, Dewar, klystron test stand, and a remote outdoor enclosure were constructed. Hydrogen safety approval for the tests was obtained. Unfortunately, the hydrogen tests were never done. However, the cavity was tested at high power in LN/sub 2/ and a Q-enhancement of 2.02 was recorded, compared to 2.7 expected theoretically. This work is now continuing with improved measuring techniques using some of the same apparatus. It is the purpose of this paper to report on the early work and to reference its continuation today.
Date: January 1, 1986
Creator: Liska, D.; Uher, J. & Potter, 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

Design considerations and prototype performance of the Fermilab Main Injector dipole

Description: The Main Injector project at Fermilab requires a dipole with good field quality from 0.1 T to 1.73 T with ramps to full field at up to 2.4 T/s over an aperture of 10 {times} 5 cm. Operation of this magnet for the variety of purposes proposed for the Main Injector results in a design with low inductance, large copper cross section, and field uniformity sufficient for high intensity injection and efficient slow resonant extraction. The resulting design is presented, along with measurement results of a prototype magnet emphasizing the field uniformity. 6 refs., 4 figs., 2 tabs.
Date: May 1, 1991
Creator: Harding, D.J.; Bleadon, M.E.; Brown, B.C.; Desavouret, E.; Garvey, J.D.; Glass, H.D. et al.
Partner: UNT Libraries Government Documents Department

Magnets for high energy colliders

Description: The problem of producing, preserving and stably colliding low emittance bunches for long periods of time is a formidable problem involving questions of jitter, dynamic alignment and reproducibility associated with magnetic and mechanically hysteresis. Permanent magnets provide ideal solutions for lower capital and operating costs. Because they are light in weight, compact and require no power or cooling they are easy to use, stable and uniquely reliable. With their low permeability this implies a minimal impact on the surrounding environment and vice versa. For example, they are ideal for final focus systems embedded in particle detectors with strong solenoidal fields while their strength and compactness minimizes the solid angle they subtend around the interaction point (IP) as well as their target thickness along the beam line. We discuss calculations there /rvec B/ is a nonlinear, anisotropic function of /rvec H/. The results explain discrepancies observed measurement and calculation of permanent magnet systems and indicate good multipoles are possible with far higher strengths than previously obtained. We extend previous calculations on the obtainable gradients for different types of quadrupoles down to 1 mm bore radii where 2000 T/m appears possible with conventional designs and available materials. We discuss why much higher gradients are possible by the same means. Additional specifications for PM manufacturers are recommended. 14 refs., 5 figs.
Date: March 1, 1989
Creator: Spencer, J. & Stucki, H.
Partner: UNT Libraries Government Documents Department

Test of two 1. 8 M SSC model magnets iwth iterated design

Description: We report results from two 1.8 m-long dipoles built as part of the Superconducting Super Collider (SSC) RandD program. These magnets contain design changes made on both the 1.8 m and the full-length 17 m dipoles to improve quench performance, magnetic field uniformity, and manufacturability. The magnets reach 8 T with little training. 10 refs., 5 figs., 1 tab.
Date: January 1, 1989
Creator: Wanderer, P.; Cottingham, J.G.; Dahl, P.; Ganetis, G.; Garber, M.; Ghosh, A. et al.
Partner: UNT Libraries Government Documents Department

An alternate method for designing dipole magnet ends

Description: Small bore superconducting dipole magnets, such as those for the SSC, often have problems in the ends. These problems can often be alleviated by spreading out the end windings so that the conductor sees less deformation. This paper presents a new procedure for designing dipole magnet ends which can be applied to magnets with either cylindrical or conical bulged ends to have integrated field multipoles which meet the constraints imposed by the SSC lattice. The method described here permits one to couple existing multiparameter optimization routines (i.e., MINUIT with suitable independent parameter constraints) with a computer code DIPEND, which describes the multiples, so that one can meet any reasonable objective (i.e., minimizing integrated sextupole and decapole). This paper will describe how the computer method was used to analyze the bulged conical ends for an SSC dipole. 6 refs, 6 figs, 2 tabs.
Date: August 1, 1988
Creator: Pope, W.L.; Green, M.A.; Peters, C.; Caspi, S. & Taylor, C.E.
Partner: UNT Libraries Government Documents Department

The location of the quench origin in a superconducting accelerator magnet

Description: A method of calculating the initial rate of rise of the resistive voltage in a quenching superconducting magnet is described. Comparison of such calculations with data from spontaneously occurring quenches gives the location of the quench origin since the normal state resistance of the conductor is determined by its position in the windings due to the magnetoresistance of the copper matrix. The characteristics of the voltage buildup is used to separate quenches occurring in low field regions, such as the magnet ends, from those starting in the two-dimensional straight section of the coil. The magnitude of V dot is a measure of performance and can be used to determine if the magnet is reaching the maximum current permitted by the conductor parameters.
Date: January 1, 1987
Creator: Ghosh, A.K.; Robins, K.E. & Sampson, W.B.
Partner: UNT Libraries Government Documents Department

Mechanical and electromagnetic design of the SSC QSE101 quadrupole ends

Description: The SSC collider magnets feature grouped ends in which cables of a particular coil remain stacked together as they are gent around the end. methods have been developed to form the ends in such a way that mechanical stresses are lowered and field quality is optimized. This paper discusses techniques of end turn design and presents calculations of harmonics and peak fields for the SSC quadrupole QSE101. 5 refs., 9 figs.
Date: June 1, 1991
Creator: Orrell, D.; Nobrega, F.; Lilly, J.; Snitchler, G.; Jayakumar, J.; Venkatraman, V. (Superconducting Super Collider Lab., Dallas, TX (United States)) et al.
Partner: UNT Libraries Government Documents Department

Status of the SUNY superconducting RFQ

Description: A RFQ resonator is presently being developed at SUNY. This resonator is a prototype for a chain of six short ({approximately}0.5m long), superconducting (Pb plated Cu), 50 MHz resonators designed to accelerate beam from {beta} = 0.01 to 0.05. The chain accepts a prebunched beam to save on superconducting length. The resonators are of four-rods type with vane-like electrodes. The prototype resonator is designed to accelerate ions of q/A = 1/6 from {beta} = 0.030 to 0.036, operating at a peak surface electric field of 16 MV/m. The electrodes have a rather high modulation parameter of 4 and a wide aperture of 1.57 cm radius. These values are chosen to maximize the accelerating field (E{sub a}) for a given peak surface electric field (E{sub s}). At the design value of E{sub s} = 16 MV/m, the resonator is estimated to have E{sub a} = 2.0 MV/m, stored energy of 4 J, peak surface magnetic field of 360 Gauss, and inter-vane voltage of 0.42 MV. Results of RF tests on this prototype resonator will be presented. 7 refs., 3 figs.
Date: January 1, 1991
Creator: Jain, A.; Ben-Zvi, I.; Paul, P.; Wang, H. (Brookhaven National Lab., Upton, NY (United States)) & Lombardi, A. (Istituto Nazionale di Fisica Nucleare, Legnaro (Italy). Lab. Nazionale di Legnaro)
Partner: UNT Libraries Government Documents Department

Offset coil designs for superconducting magnets, a logical development

Description: Dipoles and quadrupoles for any new, large proton ring must be stronger, smaller and have better field shape (systematic error) than those used in the Doubler. The present two-shell designs are rigid in that the coils are too thin but cannot be relatively fatter without destroying the field quality. An examination of the coil shapes for dipoles and quadrupoles which produce perfect fields from a uniform current density shows clearly that our persistent use of a circular form for the inner surface of the coils is a poor approximation. When this is corrected by ''offsets'' there is a striking improvement both in the strength of fields and in the field quality. The same analysis makes clear that the efficient use of superconductor and the overall magnet size is determined by the perfect coil shapes. Any reasonable magnet will not differ significantly from the ideal for these parameters. This will be particularly helpful in setting design goals for very large quadrupoles. The offset two-shell dipole design preserves the mechanical features of the highly successful, resilient doubler magnets while greatly extending the performance.
Date: March 1, 1986
Creator: Collins, T.
Partner: UNT Libraries Government Documents Department

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

Description: The 50 mm aperture collider dipole magnet uses stainless steel collars to position the conductors at the locations specified by the magnetic design and to prestress the coil to prevent conductor motion under excitation. The collars are supported by the vertically-split yoke and cold mass skin to reduce their deflection under excitation. The collar interior is designed to give the coil its required shape at the operating temperature taking into account all deflections that occur from assembly and cooldown. 13 refs., 2 figs., 1 tab.
Date: May 1, 1991
Creator: Strait, J.; Kerby, J.; Bossert, R.; Carson, J. (Fermi National Accelerator Lab., Batavia, IL (USA)); Spigo, G. & Turner, J.R. (Superconducting Super Collider Lab., Dallas, TX (USA))
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 collider dipole magnet end mechanical design

Description: This paper describes the mechanical design of the ends of Superconducting Super Collider dipole magnets to be constructed and tested at Fermilab. Coil end clamps, end yoke configuration, and end plate design are discussed. Loading of the end plate by axial Lorentz forces is discussed. Relevant data from 40 mm and 50 mm aperture model dipole magnets built and tested at Fermilab are presented. In particular, the apparent influence of end clamp design on the quench behavior of model SSC dipoles is described. 8 refs., 3 figs.
Date: May 1, 1991
Creator: Delchamps, S.W.; Bossert, R.C.; Carson, J.; Ewald, K.; Fulton, H.; Kerby, J. et al.
Partner: UNT Libraries Government Documents Department

SSC dipole vacuum vessel support placement analysis

Description: Early (superconducting super collider) SSC dipole model magnets were supported at five points along their length by feet welded to the vacuum vessel. The cold mass was supported at the same five points. The number of supports was determined such that the maximum cold mass deflection between supports was limited to 0.010 inches as specified in the first version of the SSC Design Criteria. The spacing between supports was determined to minimize the sag of the cold mass, given five supports. This paper analyzes the deflection of the cold mass and vacuum vessel as a result of these supports. 4 refs. (LSP)
Date: August 1, 1987
Creator: Nicol, T.H.
Partner: UNT Libraries Government Documents Department

Tests of 40 mm SSC dipole model magnets with vertically split yokes

Description: Several 1 meter long, 40 mm aperture model SSC dipole magnets with vertically split yokes have been built and tested at Fermilab. In addition to the yoke design, these magnets were used to evaluate several variants of the collet clamps which apply prestress to the magnet ends. The magnets were instrumented with voltage taps for quench localization and strain gage based devices for measuring stresses, forces and deflections resulting from cooldown and excitation. Test were carried out in a vertical dewar at temperatures from 3.8{degree}K to 4.4{degree}K. The quench and mechanical behavior of these magnets will be presented and magnetic field measurements will be shown. A comparison with an earlier series of magnets with horizontally split yokes will be made. 7 refs., 4 figs., 1 tab.
Date: May 1, 1991
Creator: Koska, W.; Bossert, R.; Coulter, K.J.; Delchamps, S.; Gourlay, S.; Kinney, W. et al.
Partner: UNT Libraries Government Documents Department

Bipolar and unipolar tests of 1. 5m model SSC collider dipole magnets at Fermilab

Description: Tests have been performed at Fermilab on 1.5 m magnetic length model SSC collider dipoles using both bipolar and unipolar ramp cycles. Hysteresis energy loss due to superconductor and iron magnetization and eddy currents is measured and compared as a function of various ramp parameters. Additionally, magnetic field measurements have been performed for both unipolar and bipolar ramp cycles. Measurements such as these will be used to estimate the heat load during collider injection for the SSC High Energy Booster dipoles. 9 refs., 4 figs.
Date: May 1, 1991
Creator: Lamm, M.J.; Ozelis, J.P.; Coulter, K.J.; Delchamps, S.; Jaffery, T.S.; Kinney, W. et al.
Partner: UNT Libraries Government Documents Department

Magnet current regulation in the SSC

Description: This paper investigates the transient response, the stability and the regulation characteristics of a system designed to power the SSC magnets. Considering the magnet system as a transmission line, the performance of the regulation system was investigated under perturbations on the voltage power supply and changes in the current reference. The influence of the damping resistors on the transient reponse was included. Differential current transductors were included to minimize the tracking errors between the electrically isolated sectors. A comparison was made for the two cases, with and without the differential loops. System performance was investigated during ramping of the magnets and during steady state full field operation.
Date: April 1, 1986
Creator: Calvo, O.; Tool, G. & Wolff, D.
Partner: UNT Libraries Government Documents Department

Full length SSC R and D dipole magnet test results

Description: Four full scale SSC development dipole magnets have been tested for mechanical and quench behavior. Two are of a design similar to previous magnets but contain a number of improvements, including more uniform coil size, higher pre-stress and a redesigned inner-outer coil splice. One exceeds the SSC operating current on the second quench but the other appears to be limited by damaged superconductor to a lower current. The other two magnets are of alternate designs. One trains erratically and fails to reach a plateau and the other reaches plateau after four quenches. 12 refs., 4 figs.
Date: March 1, 1989
Creator: Strait, J.; Bleadon, M.; Brown, B.C.; Hanft, R.; Kuchnir, M.; Lamm, M. et al.
Partner: UNT Libraries Government Documents Department

Straight ends for superconducting dipole magnet using ''constant perimeter'' geometry

Description: The ends of the SSC Dipole magnets are a very critical aspect of the superconducting cable windings needed for this large project. The internal coils, where the radius at the pole is as small as 3/10 of an inch for the first turn, are difficult to form with the very stiff cable, and a high tension is needed. The curing operation on the coils is performed in a heated forming press which applies an important additional stress on the superconducting wire and insulation. A new design of this sensitive region of the magnets was performed at LBL, and several prototypes were built and tested. In this paper the construction method used to solve some of the most critical problems is exposed along with a description of the experimental work in progress. 3 refs., 2 figs.
Date: February 1, 1989
Creator: Royet, J.
Partner: UNT Libraries Government Documents Department

Design of 15 mm collars for SSC dipole magnets

Description: Ten 1-m long dipole magnets of the SSC design ''D'' cross section have been constructed and tested. In each model a collar type structure was used to contain and support the coil assembly at assembly and during operation at 4K. The collar structure must provide enough coil compression to minimize training and guarantee the coil cross section dimensions. Three types of collar designs were used. The behavior, measured and predicted, of two types of 15 mm stainless steel collars used on eight of the ten models is examined. The mechanical measurement of the 15 mm stainless steel collars used on eight 1-m dipole models are given. Observed behavior and preliminary design criteria are discussed. In order to better understand observed collar behavior and to evaluate new designs, finite element analysis of the collar designs was undertaken, and results are correlated with measured behavior. The behavior of alternate collar designs is predicted. 3 refs., 19 figs. (LEW)
Date: March 1, 1986
Creator: Peters, C.
Partner: UNT Libraries Government Documents Department

Collarless, close-in, shaped iron aperture designs for the SSC (Superconducting Super Collider) dipole

Description: The nominal-design SSC (Superconducting Super Collider) dipole encloses the coil in an iron yoke having a circular aperture. The radial gap between the coil and the iron is about 15 mm to provide space for a strong annular collar around the coil, and also to reduce the effects of iron saturation on central field harmonics. The 15 mm gap also reduces the desirable dipole field contributed by the iron. The present paper gives a coil and aperture configuration in which the gap is reduced to 5 mm at the midplane, in which the aperture is shaped to reduce the unwanted effects of iron saturation. The transfer function is increased about 5% at 6.6 Tesla and the unwanted harmonics are within SSC tolerances at all field levels. These designs would require that the yoke and containment vessel absorb the stresses due to assembly and magnetic forces. A short magnet is being built with a close-in shaped iron aperture and existing coil geometry to assess the benefits of this concept. 7 refs., 3 figs., 6 tabs.
Date: January 1, 1989
Creator: Gupta, R.C. & Morgan, G.H.
Partner: UNT Libraries Government Documents Department

Stability of bellows used as expansion joints between superconducting magnets in accelerators

Description: For superconducting magnets, one needs many bellows for connection of various helium cooling transfer lines. There could be approximately 20,000 magnet interconnection bellows in the SSC exposed to an internal pressure. When axially compressed, internally pressurized, or insufficiently supported at their ends, bellows can become unstable, leading to gross distortion or complete failure. If several bellows are contained in a magnet assembly, failure modes might interact. If designed properly large bellows can be used to connect the large tubular shells that support the magnet iron yokes and superconducting coils and contain supercritical helium for magnet cooling. We investigate here bellows design features and end supports to insure that instabilities will not occur in the bellows pressure operating region, including some margin. A model of three superconducting accelerator magnets connected by two large bellows is analyzed in order to ascertain that support requirements are satisfied and in order to study interaction effects between the two bellows. Specific details of large and small bellows design and reliability for our application will be addressed.
Date: January 1, 1991
Creator: Shutt, R.P. & Rehak, M.L.
Partner: UNT Libraries Government Documents Department