ALS superbend magnet system - eScholarship

ALS Superbend Magnet System J. Zbasnik † , S. T. Wang †† , J. Y. Chen †† , G. J. DeVries † , R. DeMarco † , M. Fahmie † , A. Geyer † , M. A. Green † , J. Harkins † , T. Henderson † , J. Hinkson † , E. H. Hoyer † , J. Krupnick † , S. Marks † , F. Ottens † , J. A. Paterson † , P. Pipersky † , G. Portmann † , D. A. Robin † , R. D. Schlueter † , C. Steier † , C. E. Taylor † , R. Wahrer †† II. Abstract—The Lawrence Berkeley National Laboratory is preparing to upgrade the Advanced Light Source (ALS) with three superconducting dipoles (Superbends). In this paper we present the final magnet system design which incorporates RD each cell has three 1-m long combined- function gradient bending magnets. Each bending magnet generates photons with a critical energy of 3.1 keV, which are delivered to users via 48 ports. A study [1] commissioned to consider ways of increasing the photon energy concluded that an attractive approach would be to increase the bending field to 5 T at three locations in the storage ring with superconducting dipoles (Superbends) to generate photons with a critical energy around 12 keV. A Superbend R&D program was carried out which culminated in a successful magnet that did not quench before reaching critical current. It could be ramped to full field in less than 100 sec while submerged in liquid helium and had acceptable field quality [2]. This magnet was used as the starting point for the design and fabrication of the accelerator-grade Superbend magnet system described in this paper. The detailed design and fabrication is underway at Wang NMR, under contract to LBNL. We report preliminary test results for the first of four Superbend magnets. Manuscript received September 18, 2000. This work was performed at the Lawrence Berkeley National Laboratory with the support of the Director, Office of Science, Office of High Energy and Nuclear Physics, High Energy Physics Division, U. S. Department of Energy under Contract No, DE-AC03- 76SF00098. Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 USA. Author addresses are available at www.lbl.gov. Wang NMR, 550 North Canyons Parkway, Livermore, CA 94550 USA. Table II lists the operational goals, which will minimize the impact of the Superbends on ALS operation. These were derived from accelerator physics considerations [4]. TABLE II S UPERBEND O PERATIONAL G OALS ( IN ORDER OF PRIORITY ) Quantity Field Ripple Field Tracking Ramping Rate (204A to 291 A) Value ≤ 5 × 10 for frequencies > 0.01 Hz ≤ 1.7 × 10 −5 for frequencies ≤ 0.01 Hz ≈ 300 mA at 1 A/s 1.5 A/s to match present ALS operation 3 A/s to match ALS possible upgrade B. Coil and Cold Mass Design The conductor specified for the ALS Superbend was developed in the R&D program [2] and was supplied by Outokumpu per the parameters in Table III.