William S. Gilbert

ESCAR Superconducting Magnet System

The ESCAR (Experimental Superconductinq Aqcelerator Ring) project has been described previously. , Twentyfour superconducting dipoles each about 1 meter long, provide the guide field for this proton acceleratorstorage ring. Injection of 50 MeV protons corresponds to a 3 kG central dipole field, and a peak proton energy of 4.2 GeV corresponds to a 46 kG central field. Thirtytwo quadrupoles provide focusing.

Performance of Dipole Magnets in Helium II

Data from tests in He II of four 1-meter-long magnets are presented. The maximum quench current is increased up to 30 percent, compared with tests in He I. Data from calorimetric measurements of heat generated during cyclic operation are presented. Quenches were induced by heaters placed near the conductor, and the energy required to induce quenches in He II and in He I are compared.

Sextupole Correction Coils for SSC Model Dipoles

Local correction of the sextupole error field is proposed for the dipoles of the SSC. This requirement is imposed on the design by the high field quality required both during injection at low fields and during colliding beam operation at high fields. Error fields in the main dipole windings due to superconductor magnetization and conductor misplacements add unwanted sextupole and decapole magnetic field terms. To correct the sextupole error field we have constructed sextupole coils made of a single layer of superconducting wire and have mounted them with high precision on the stainless steel bore tube. These correction coils have been operated with 1 meter long SSC model dipoles in both the self-powered and externally-powered modes. The sextupole field in the bore has been reduced by as much as a factor of 50. The level of correction depends strongly on the angular alignment of the correction coil with respect to the sextupole error field it is to correct. Results of tests, performance of the correction coils and alignment requirements for the system are presented.

Design and Performance of 40 MM, 6.5 T, Collared, Cold-Iron Model Magnets

Model magnets have been built and tested at the Lawrence Berkeley Laboratory to verify a candidate design for the main bending magnets of the SSC. Construction of this series of dipole models was begun in October 1984 and will be completed in October 1985. To date, three models with collars, C1, C2, and C3, have been completed. Model C1 and C2 have been tested.

A Layer-Wound, 8.7-Tesla Superconducting Dipole Magnet

A superconducting dipole magnet is discussed in detail and test results are presented. The performance of the dipole magnet demonstrates that it can operate successfully at least at the lower end of fields in He 1 at about 4.3K and in He 11 between 1.8 and 2.16K. A photograph of the magnet is shown and a cross section is given. One of the goals of fabrication was to maintain the first turn of each layer in positive compression against its respective pole island during operation at the highest current. Target values for the precompression were determined for each layer.

Items from the Construction of ESCAR

ESCAR is an experimental superconducting accelerator which is being built at Lawrence Berkeley Laboratory to gain timely, full-scale experience in the construction and operation of a fully cryogenic accelerator. A report is given of the construction of several non-conventional items.

Radiation Problems with High-Energy Proton Accelerators

We shall restrict the discussion to proton accelerators in the multi-GeV energy range and of the alternating-gradient synchrotron type, with special attention given to the existing 30-GeV and the proposed 200-to 300-GeV machines. Radiation problems can be divided into two broad groups: those produced by the accelerator while it is running and those associated with the shut-down machine. The expense and difficulty of coping with these radiation problems influence the choice of design beam intensity. The problems while the machine is running are penetration of radiation through the shielding, muon shielding, penetration of radiation through ducts and labyrinths, skyshine, diffusion of radioactive air, and radiation damage to components. Some results of an LRL-CERN-Rutherford shielding experiment on the CERN-PS are presented. Problems of the shut-down accelerator include induced activity in the machine components and enclosure walls. These radiation fields affect maintenance procedures and require appropriate handling tools and shielded vehicles.

ALTERNATIVE DIPOLE MAGNETS FOR ISABELLE

LBL-14215 SUMAG-62 LBL—14215 DE82 0 2 0 5 4 9 ALTERNATIVE 01 POLE MAGNETS FOR ISABELLE* C. Taylor, R. Althaus, S. Caspi, W. G i l b e r t , W. Hassenzahl R. Meuser, 0. Rechen, and R. Warren Hay 1982 Accelerator and Fusion Research D i v i s i o n Lawrence Berkeley Laboratory University of C a l i f o r n i a Berkeley, C a l i f o r n i a 94720 *This work was supported by the Diractor, Office o f Energy Research, Office of Hiqh Enerqy and Nuclear Physics, High Energy Physics D i v i s i o n , U. S. Dept. of Energy, under Contract No. DE-AC03-76SF00098. DISTHIBUTICK OF THiS I16CUWKT IS UNLIMITEU

Superconducting Pulsed Synchrotron Dipole and DC Beam Transport Magnets

Pulsed dipoles for superconducting synchrotron application have been built and tested. Low cyclic loss up to a central dipole field of 23kG has been demonstrated. A large dc dipole transport element for Bevatron area use has been built and tested; the warm bore aperture is 8 in. and the design central field is 42kG. Details of this magnet and a companion quadrupole doublet follow.

Measured Losses in Pulsed Superconducting Solenoid Magnets

AC, or cyclic, energy losses were determined in geometrically similar solenoids wound with single-core, untwisted-multicore, and twisted-multicore composite superconductor. The losses were larger in the untwisted-multicore conductor than in the corresponding single-core case. When the multicore conductor was twisted, the losses were markedly reduced. The multicore conductor, when both twisted and untwisted, was remarkably free of flux jumps; thus the filament diameter of 0.0013 in. may be small enough to provide intrinsic stability.