D. A. Gross

Bio: D. A. Gross is an academic researcher from Fermilab. The author has contributed to research in topics: Magnet & Fermilab. The author has an hindex of 6, co-authored 8 publications receiving 103 citations.

AC loss in energy doubler magnets

Abstract: A computerized ac loss measurement system was developed and more than 50 magnets were measured. The ac losses were very much dependent on various factors such as conductor surface and pressure applied to coil windings. Statistical correlation between quench current and ac loss will be shown. From the measurements of magnets made of different kinds of cables, most of the eddy current loss was found to be in the inner coil of the double layer structure. Among the three kinds of eddy current loops, the one which comes from the interconnection between crossing strands was proved to be the major part of the eddy current loss. Such an eddy current can be almost eliminated, by the use of a copper oxide resistive layer between strands. Thus, the Energy Doubler/Saver magnets, will be operated up to 4.5T with a loss of about 450J/cycle per each dipole magnet. To estimate real time power loss instead of total loss throughout whole cycle, a new method was tried and successful results were obtained.

Magnetic Field Properties of Fermilab Energy Saver Dipoles

Abstract: At Fermilab we have operated a production line for the fabrication of 901 21 foot long superconducting dipoles for use in the Energy Saver/Doubler. At any one time 772 of these dipoles are installed in the accelerator and 62 in beamlines; the remainder are spares. Magnetic field data are now available for most of these dipoles; in this paper we present some of these data which show that we have been able to maintain the necessary consistency in field quality throughout the production process. Specifically we report harmonic field coefficients, showing that the mechanical design permits substantial reduction of the magnitudes of the normal and skew quadrupole harmonic coefficients; field shape profiles; integral field data; and field angle data. Details of the measurement apparatus and procedures are described elsewhere.

Report on the Production Magnet Measurement System for the Fermilab Energy Saver Superconducting Dipoles and Quadrupoles

Abstract: The measurement system and procedures used to test more than 900 superconducting dipole magnets and more than 275 superconducting quadrupole magnets for the Fermilab Energy Saver are described. The system is designed to measure nearly all parameters relevant to the use of the magnets in the accelerator including maximum field capability and precision field measurements. The performance of the instrumentation with regard to precision, reliability, and operational needs for high volume testing will be described. Previous reports have described the measurement system used during development of the Saver magnets from which this system has evolved.

Fermilab Tevatron quadrupoles

Abstract: Details on the design, construction, and performance tests of Energy Saver/Doubler quadrupoles are presented along with recent data from the test of a special high gradient low beta prototype quadrupole.

Magnetization Characterization Study for the Energy Saver/Doubler Dipoles

Abstract: One of the challenging problems in superconducting accelerator dipoles is their dynamic behavior under ramping magnetic field produced loads. Their behavior can be observed with hysteretic measurement of the energy flow in the magnet. This technique, first described in detail by M.N.Wilson, will determine changes in inductance, deflection of coils, dynamic losses, the superconducting cable's critical current vs. field and coupling curves, and iron shield saturation reproducibility. These measurements, when cross correlated with integral field, NMR and harmonic data yield a comprehensive characterization of the magnet. Data are presented for several magnets tested in the Magnet Test Facility of Fermilab. Measurements of inductance changes of a few percent and deflections of a few one-one thousandths of an inch are given. These data can now be routinely obtained on a production basis, therefore yielding a more complete characterization of the accelerator dipole's dynamic behavior.

Electromagnetic design of superconducting dipoles based on sector coils

Abstract: We study the coil layouts of superconducting dipoles for particle accelerators based on the sector geometry. We show that a simple model based on a sector coil with a wedge allows us to derive an equation giving the short sample field as a function of the aperture, coil width, cable properties, and superconducting material. The equation agrees well with the actual results of several dipole coils that have been built in the past 30 years. The improvements due to the grading technique and the iron yoke are also studied. The proposed equation can be used as a benchmark to judge the efficiency of the coil design, and to carry out a global optimization of an accelerator layout.

First Thoughts on a Higher-Energy LHC

Abstract: We report preliminary considerations for a higher-energy LHC (“HE-LHC”) with about 16.5 TeV beam energy and 20-T dipole magnets. In particular we sketch the proposed principal parameters, luminosity optimization schemes, the new HE-LHC injector, the magnets required, cryogenics system, collimation issues, and requirements from the vacuum system.

Studies of time dependence of fields in Tevatron superconducting dipole magnets

Abstract: The time variation in the magnetic field of a model Tevatron dipole magnet at constant excitation current has been studied. Variations in symmetry allowed harmonic components over long time ranges show a log t behavior indicative of 'flux creep'. Both short-time-range and long-time-range behavior depend on the excitation history. Similar effects are seen in the remnant fields present in full-scale Tevatron dipoles following current ramping. Both magnitudes and time dependences are observed to depend on details such as ramp rate, flattop duration, and number of ramps. In a few magnets, variations are also seen in symmetry-disallowed harmonics. >

The Development of Superconducting Magnets for Use in Particle Accelerators: From the Tevatron to the LHC

Abstract: Superconducting magnets have played a key role in advancing the energy reach of proton synchrotrons and enabling them to play a major role in defining the Standard Model. The problems encountered and solved at the Tevatron are described and used as an introduction to the many challenges posed by the use of this technology. The LHC is being prepared to answer the many questions beyond the Standard Model and in itself is at the cutting edge of technology. A description of its magnets and their properties is given to illustrate the advances that have been made in the use of superconducting magnets over the past 30 years.