Results from heater-induced quenches of A 4. 5 m Reference Design D dipole for the SSC

Quench studies were performed using a 4.5 m long Reference Design D, SSC dipole to determine the temperature rise of the magnet conductor during a quench by measuring the resistance of the conductor cable in the immediate vicinity of the quench. The single bore magnet was wound with improved NbTi conductor in a 2-layer cosine theta coil configuration of 4.0 cm inner diameter. Eight pairs of voltage taps were installed at various locations on the right side of the inner coil of the magnet. ''Spot'' heaters were centrally located between the voltage taps of 4 of these pairs on the midplane turn of the inner coil to initiate magnet quenches. A redundant array of voltage taps and heaters was also installed on the left side of the inner coil. The resistance of the conductor was obtained from observations of the current and voltage during a magnet quench. The temperature of the conductor was then determined by comparing its resistance to an R vs T curve appropriate for the conductor. The quantity ..integral.. I/sup 2/dt and the temperature, T, are presented as a function of current, and the maximum conductor temperature is shown as a function of ..integral.. I/sup 2/dt. Measured longitudinal and azimuthal quench propagation velocities are also presented as a function of magnet current, and the temperatures at several locations on the inner magnet coil are plotted as a function of the time after a quench was initiated

OVERVIEW OF THE AGS COLD SNAKE POWER SUPPLIES AND THE NEW RHIC SEXTUPOLE POWER SUPPLIES

The two rings in the Relativistic Heavy Ion Collider (RHIC) were originally constructed with 24 sextupole power supplies, 12 for each ring. Before the start of Run 7, 24 new sextupole power supplies were installed, 12 for each ring. Individual sextupole power supplies are now each connected to six sextupole magnets. A superconducting snake magnet and power supplies were installed in the Alternating Gradient Synchrotron (AGS) and commissioned during RHIC Run 5, and used operationally in RHIC Run 6. The power supply technology, connections, control systems and interfacing with the Quench Protection system for both these systems will be presented

RHIC power supplies-failure statistics for runs 4, 5 and 6

The two rings in the Relativistic Heavy Ion Collider (RFIIC) require a total of 933 power supplies to supply current to highly inductive superconducting magnets. Failure statistics for the RHIC power supplies will be failure associated with the CEPS group's responsibilities. presented for the last three RHIC runs. The failures of the power supplies will be analyzed. The statistics associated with the power supply failures will be presented. Comparisons of the failure statistics for the last three RHIC runs will be shown. Improvements that have increased power supply availability will be discussed

Vibration Measurements to Study the Effect of Cryogen Flow in Superconducting Quadrupole.

The conceptual design of compact superconducting magnets for the International Linear Collider final focus is presently under development. A primary concern in using superconducting quadrupoles is the potential for inducing additional vibrations from cryogenic operation. We have employed a Laser Doppler Vibrometer system to measure the vibrations in a spare RHIC quadrupole magnet under cryogenic conditions. Some preliminary results of these studies were limited in resolution due to a rather large motion of the laser head as well as the magnet. As a first step towards improving the measurement quality, a new set up was used that reduces the motion of the laser holder. The improved setup is described, and vibration spectra measured at cryogenic temperatures, both with and without helium flow, are presented

Alignment of the high beta magnets in the RHIC interaction regions

The betatron functions inside the triplet quadrupoles in the Relativistic Heavy Ion Collider-RHIC are of the order of 1,500 m, necessitating additional attention in the alignment procedure. On each side of the interaction regions eight cryogenic elements (six quadrupoles and two horizontal bending dipoles) are placed inside large cryostats. The quadrupole magnetic centers are obtained by antenna measurements with an accuracy of {+-} 60 {micro}m. The signals from the antenna were cross calibrated with the colloidal cell measurements of the same magnet. The positions of the fiducials are related to the magnet centers during the antenna measurements. Elements are positioned warm inside the cryostats, with offsets to account for shrinkage during the cool down. The supports at the middle of the two central quadrupoles are fixed, while every other element slides longitudinally inside the cryostat during cool down or warm up

Unique Features in Magnet Designs for R and D Energy Recovery Linac at BNL.

In this paper we describe the unique features and analysis techniques used on the magnets for a R&D Energy Recovery Linac (ERL) [1] under construction at the Collider Accelerator Department at BNL. The R&D ERL serves as a test-bed for future BNL ERLs, such as an electron-cooler-ERL at RHIC [2] and a future 20 GeV ERL electron-hadron at eRHIC [3]. Here we present select designs of various dipole and quadruple magnets which are used in Z-bend merging systems [4] and the returning loop, 3-D simulations of the fields in aforementioned magnets, particle tracking analysis, and the magnet's influence on beam parameters. We discuss an unconventional method of setting requirements on the quality of magnetic field and transferring them into measurable parameters as well as into manufacturing tolerances. We compare selected simulation with results of magnetic measurements. A 20 MeV R&D ERL (Fig. 1) is in an advanced phase of construction at the Collider-Accelerator Department at BNL, with commissioning planned for early 2009. In the R&D ERL, an electron beam is generated in a 2 MeV superconducting RF photo-gun, next is accelerated to 20 MeV in a 5 cell SRF linac, subsequently passed through a return loop, then decelerated to 2 MeV in the SRF linac, and finally is sent to a beam dump. The lattice of the R&D ERL is designed with a large degree of flexibility to enable the covering of a vast operational parameter space: from non-achromatic lattices to achromatic with positive, zero and negative R56 parameter. It also allows for large range tunability of Rlz and lattice RS4 parameters (which are important for transverse beam-break-up instability). Further details of the R&D ERL can be found elsewhere in these proceedings [5]. The return loop magnets are of traditional design with the following exceptions: (a) The bending radius of the 60{sup o} dipole magnets is 20 cm, which is rather small. We use 15{sup o} edges on both sides of the dipoles to split very strong focusing evenly between the horizontal and vertical planes (so-called chevron-magnet). (b) The requirements on field quality of the loop's quadrupoles had been determined by the requirement to preserve a very low normalized transverse slice emittance of electron beam ({var_epsilon} {approx} 1 mm-mrad). We used direct tracking of a sample electron beam to verify a high degree of the emittance preservation. (c) Each quadrupole is equipped with a dipole trim coil, which can be also used to excite a sextupole component, if required, for emittance preservation of e-beam with a large energy spread. One of the unique features of all ERLs is the necessity for merging low and high energy electron beams. In the R&D ERL, 2 MeV from the SRF gun merges with the 20 MeV electron beam coming around the return loop into the same trajectory at a position within the SRF linac. In the linac, injected bunch is accelerated to 20 MeV, while the returned or ''used'' bunch is decelerated to 2 MeV. The challenge for a merger design is to provide conditions for emittance compensation [5] and also for achromatic conditions of a low energy, space-charge dominated-e-beam [4,6]. The scheme which satisfies these requirements (called 2-bend [4]) is used on the R&D ERL. The Z-bend is approximately 4-meter long. It bends the beam trajectory in the vertical plane. It is comprised of four dipole magnets designed to be equally focusing in both planes, with bending radius {approx} 60 cm, and bending angles of: +15{sup o}, -30{sup o}, +30{sup o} and -15{sup o}. The beam dynamics in the Z-bend results in a large-size (centimeters) near-laminar electron beam [7]. The large beam size and very low slice emittance of the e-beam dictates the tolerances on the magnetic field to be very tight. The integrated nonlinear kicks should not exceed {approx} 20 micro-radian per magnet at a typical radius {approx} 1 cm. The magnets in the Z-bend are rather short (15 cm effective length for the 15{sup o} magnet) and have a rather large aperture of 6 cm. Analysis predicts that the influence of various field components on the emittance growth are complicated by the fact that the beam trajectory bends significantly in the Einge fields. Hence, we decided to use direct tracking in the calculated fields extracted from Opera3d of test beam to evaluate and to minimize influence of magnetic field on the beam emittance. In addition, we used predictions of Opera3d and compared them with results of magnetic measurements for the return loop dipole and quadrupole. One of the features of the loop magnets is that they are fabricated with a very high geometric tolerance, allowing them to be an excellent test bed for bench-marking our predictions. Agreement with the prediction provides us with sufficient confidence that Z-bend magnets will preserve beam emittance

Common Coil Magnet Program at Bnl.

The goal of the common coil magnet R&D program at Brookhaven National Laboratory (BNL) is to develop a 12.5 T, 40 mm aperture dipole magnet using ''React and Wind Technology'' with High Temperature Superconductors (HTS) playing a major role. Due to its ''conductor friendly'' nature, the common coil design is attractive for building high field 2-in-1 dipoles with brittle materials such as HTS and Nb{sub 3}Sn. At the current rate of development, it is expected that a sufficient amount of HTS with the required performance would be available in a few years for building a short magnet. In the interim, the first generation dipoles will be built with Nb{sub 3}Sn superconductor. They will use a ''React and Wind'' technology similar to that used in HTS and will produce a 12.5 T central field in a 40 mm aperture. The Nb{sub 3}Sn coils and support structure of this magnet will become a part of the next generation hybrid magnet with inner coils made of HTS. To develop various aspects of the technology in a scientific and experimental manner, a 10-turn coil program has been started in parallel. The program allows a number of concepts to be evaluated with a rapid throughput in a cost-effective way. Three 10-turn Nb{sub 3}Sn coils have been built and one HTS coil is under construction. The initial test results of this ''React & Wind'' 10-turn coil program are presented. It is also shown that a common coil magnet design can produce a field quality that is as good as a conventional cosine theta design