We describe a major paradygm shift in in the approach to the production of synchrotron radiation This change will considerably improve the scientific capabilities of synchrotron light sources. We introduce plans for an upgrade of the National Synchrotron Light Source (NSLS). This upgrade will be based on the Photoinjected Energy Recovering Linac (PERL). This machine emerges from the union of two technologies, the laser-photocathode RF gun (photoinjector) and superconducting linear accelerators with beam energy recovery (Energy Recovering Linac). The upgrade will bring the NSLS users many new insertion device beam lines, brightness greater than 3rd generation lightsource's and ultra-short pulse capabilities, not possible with storage ring light sources.

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S u b A t t e d t o the 1995 P a r t i c l e A c c e l e r a t o r C o n f e r e n c e , 'Dallas, Texas, 'May 1-5, 1995. is being considered for a coherent synchrotron radiation source. The existing 211 MHz warm cavity will be replaced with a 5-cell2856 MHz superconducting RF cavity, driven by a series of 2 kW klystrons. The RF system will provide a total VRF of 1.5 MV to produce OL = 0.3 mm electron bunches at an energy of 150 MeV.Superconducting technology significantly reduces the required space and power needed to achieve the higher voltage. It is the purpose of this paper to describe the superconducting RF system and cavity, power requirements, and cavity design parameters such as input coupling, Quality Factor, and Higher Order Modes. II. INTRODUCTIONThe XLS Phase I storage ring is a compact racetrack-shaped ring at the National Synchrotron Light Source of Brookhaven National Laboratory. Using a warm 211 MHz RF cavity, currents of up to 0.75 A in 6 bunches have previously been stored at energies ranging from 120 to 200 MeV. Installation of a 5-cell2856 MHz superconducting cavity will provide an accelerating voltage of 1.5 MV for an average current of up to 5 mA, and create a source of coherent synchrotron radiation with 0.3 mm bunches at an energy of 150 MeV [l]. In order to accommodate the cavity, cryostat and helium vessel, and other associated hardware, the circumference of the ring can be increased to -9.66 from the present 8.5 m by adding a short straight section on both sides, keeping modification costs to a minimum. A partial list of the ring and RF parameters is presented in Table 1. capital cost of a closed cycle system [ Figure I]. Initially, the cryostat will be filled with normal helium; the 2' K operating temperature will be achieved through cryo-pumping. Although it is rather large, the "top-filled" cryostat is relatively easy to operate and is capable of supplying enough helium for 8 continuous hours of operation. The main difficulties foreseen are with the assembly sequences. The RF cavity will have protective windows and valves as safeguards after cleaning. The cavity design [ Figure 21 is being adapted and scaled from that currently in use at Cornell and CEBAF [2,3,4], including the input waveguide and the HOM couplers. There are 5 elliptical cells operating in the ~t mode. Scaling of CEBAF results to a 2856 MHz cavity indicates that a gradient of 8.9 MVJm is achievable. With an active length of 0.262 m, a peak cavity voltage, Vu, of 2.3 MV can be reached, which is 50% greater than specified. The order of magnitude of the unloaded quality factor Qo, is approximately lo9. A. Input CouplingAs in the CEBAF design, RF power is propagated in the TElo p = PRAD 1 P a v 0.2 III. CRYOGENICSmode through a rectangular waveguide. A hole in the broad of the waveguide that is aligned with the beam tube, The system will use a helium reservoir, operating at 2 O K, rather than circulating refrigeration because of the high initial

Abstractrepresent the state of the art. Oxford Instruments is nowThe superconducting 5 pole, 5 Tesla wiggler which has been operating in the X-17 straight section of the x-ray storage ring at the National Synchrotron Light Source (NSLS) since 1989 will soon be replaced by a new wiggler being built by Oxford Instruments with lower operating costs, higher reliability, and greater performance. The new wiggler has three modes of operation: the full wiggler with 11 poles producing 3.0 T, the partial wiggler with 5 poles at 4.7 T, and the wavelength shifter with a single pole producing 5.5 T. The full wiggler, optimized for the digital subtraction radiography program, will produce the same x-ray flux at the 33 KeV iodine K-edge as the existing wiggler operating at 4.7 T but will reduce the higher energy harmonics delivered to the target. The partial wiggler will deliver the same flux for solid state physics experiments as the existing wiggler, and the wavelength shifter will provide an elliptically polarized x-ray beam that is not now available.