The 10 x 40 cm Long Pulse neutral beam source developed at Lawrence Berkeley Laboratory has been selected as the prototype for the design of the U.s. Common Long Pulse Source to be used on TFTR, Doublet-III, and MFTF-B. The Long Pulse Source consists of a magnetic line cusp bucket with an actively cooled backplate electron dump, and a four-grid accelerator using slot apertures and water-cooled molydenum rails. Deuterium testing of the long pulse source at 120 kV, 53 A, and two-second pulse length has been completed on the Neutral Beam Engineering Test Facility, including an 8 hour, 100 shot test to demonstrate the durability and reliability of the source. Maximum 2 second beam parameters obtained (not simultaneously) are 125 kV, 58 A (deuterium), and 7.1 MW. Beam pulse length has been extended to 5 seconds at * This work was supported by the U.S. Department of Energy under Contract No. DE-AC03-16SF00098.

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 R&D test results and addresses the ALS operational concerns of alignment, availability, and economy. The design incorporates conduction-cooled Nb-Ti windings and HTS current leads, epoxy-glass suspension straps, and a Gifford-McMahon cryocooler to supply steady state refrigeration. We also present the current status of fabrication and testing.

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The Advanced Light Source (ALS) is a third generation synchrotron light source located at Lawrence Berkeley National Laboratory (LBNL). There was an increasing demand at the ALS for additional high brightness hard x-ray beamlines in the 7 to 40 keV range. In response to that demand, the ALS storage ring was modified in

Users of fusion devices have identified heating requirements for positive ion based neutral beams to include energies of 80 or 120 kV with pulse length up to 30 s. Additional requirements are low beam divergence (0.3°×1.0°; 1/e half angles), low impurity (less than 1%), high species (over 80% atomic), and cathode lifetime exceeding 5 h of beam operation. Accelerator design remains as an engineering problem, whereas most of the performance goals have required development of the plasma generator. Problems of concern which relate to the performance goals are the heat dissipation, magnetic field configuration, and cathode placement. The plasma generator was tested on TS IIA (the plasma generator testing facility) which does not have beam extraction capability but is used to evaluate efficiency, operating conditions, arc notching characteristics, species, plasma uniformity, and cathode conditioning. The source, consisting of the plasma generator mounted on the long pulse accelerator was mounted on NBETF (Neutral Beam Engineering Test Facility) for beam testing. During beam operation the back-streaming electrons add power to the source and affect the arc operation. Source durability and stability were studied at 80 kV and 40 A of accelerator current (deuterium). The arc efficiency was higher than the value used for the design. Power loading from back-streaming electrons was much less than the design level. With feedback control, plasma density and accel current were constant to ±2% during 30-s shots. The beam atomic fraction of 84%–88% (deuterium) was slightly higher than measured on TS IIA. Cathode durability was tested by operating over 500, 30-s full shots at 80 kV and 40 A of deuterium. Arc conditioning was found to be an important phase to avoid filament damage.