L. Blumberg

National Synchrotron Light Source VUV Storage Ring

A 700 MeV electron storage ring designed for synchrotron radiation applications is described. Lattice and stability calculations are presented and the vacuum, correction and injection systems are discussed.

Free Electron Laser Experiment at the NSLS 700 MeV Electron Storage Ring

A free electron laser experiment is described, to be performed with the 700 MeV electron storage ring of the National Synchrotron Light Source. The experiment is designed to study the parameters of the fel in an electron storage ring and the performance of this laser as a source of short wavelength radiation in the VUV region of the spectrum. The initial experiment will be carried out at a wave length of approximately 3000 Å, utilizing a permanent magnet undulator. For an average electron current of 1A distributed in three beam bunches, the small signal gain per pass (relative enhancement of the radiation intensity per electron bunch pass through the undulator) is calculated to be approximately 10%.

Design Status of the 2.5 GeV National Synchrotron Light Source X-Ray Ring

The present state of the design of the 2.5 GeV electron storage ring for the National Synchrotron Light Source is described. This ring will serve as a dedicated source of synchrotron radiation in the wavelength range 0.1 Å to 30 Å. While maintaining the basic high brightness features of the earlier developed lattice structure, recent work resulted in a more economical magnet system, simplified chromaticity corrections, and improved distribution of the X-ray beam lines. In addition, the adequacy of the dynamic aperture for stable betatron oscillations has been verified for a variety of betatron tunes.

The NSLS Booster Synchrotron

The Booster for the National Synchrotron Light Source electron storage rings is a 100-700 MeV synchrotron with 28.35 meter circumference. Its design current is 20 mA and its repetition rate is 1 Hertz. The lattice consists of four superperiods, each containing two focusing quadrupole magnets and two defocusing bending magnets. Nominal tunes are Vx=2.42, vy=1.37. Small values of ßx and ¿x in the bending magnets allow a damped emittance ¿x= 5.6xl0-8 meter radians. Details of the lattice, beam dynamics and beam injection and ejection are presented.

Initial Performance of the AGS Slow External Beam

The internal beam of the Brookhaven AGS has been extracted by exciting the third-integral nonlinear resonance at a horizontal tune of ?H = 8-2/3. The extraction efficiency is approximately 80% and the spill duration ~ 300 to 400 ms. The beam has been extracted over the energy range 20 to 29 GeV. Preliminary measurements of horizontal and vertical emittance give EH ? 0.036 ? in.-mrad and EV ? 0.09 ? in.-mrad. Intensity modulation of the spill is presently about 40%.

Closed Orbit Correction of the NSLS VUV Ring

We describe the results obtained from the orbit correction system in the NSLS VUV storage ring which consists of 24 PUE stations and 16 horizontal and vertical correction dipoles. The data were obtained by the PUEREAL module of the RING control program which provides automatic switching of the signal from individual electrodes of the PUE stations and provides/ a readout at harmonic of the RF frequency. The closed orbit is then calculated and corrected by measured displacements of the PUEs from the adjacent quadrupoles. The ORBIT module of the RING program was used to minimize the RMS orbit deviations choosing the most effective correctors and calculating their strengths. For the horizontal case, the correction was accomplished using 3 correctors in two iterations starting with RMS values X = 2.9 mm to X = 0.9 mm. Vertically three iterations and 6 correctors were required to correct the RMS value from Z = 6.8 mm to Z = 0.8 mm.

Fast Extraction of Debunched AGS Beam

A new system for fast extraction of the AGS beam is described in which the beam is moved rapidly across a hyper thin septum (HTS) and deflected into the aperture of a thin-septum ejection magnet (EM). The effects of momentum spread on the clearance obtained at the ejector septum are calculated. Orbit deformations from ?/2 backleg winding bumps centered at the septum and ejector azimuths are calculated and the effects of these perturbations on orbits near the ?H = 9 resonance are discussed. Loss calculations for an electrostatic HTS indicate that proton losses will be 0.1% per turn for a .002 in. diam. tungsten wire array or 0.8% per turn for a .002 in. copper foil. The ferrite beam kickers required for the fast deformation at the HTS are described. Component parameters for fractional extraction are: C15 and E15 beam kickers = .75 mrad, E10 HTS = 1.2 mrad, H10 EM = 22 mrad, and I10 EM = 21 mrad. Results of initial tests with a 2.25 m electrostatic septum of .1 mm diam. tungsten wires at 2 mm spacing are discussed.

Beam Optical Properties of the NSLS Dipoles

Presently there is much interest in low energy (< 1 GeV) electron storage rings as sources of synchrotron radiation and for studies of the free electron laser. The economics and physics of these storage rings favor the use of bending magnets with small radius of curvature and large bend angle. Here we discuss some general features of such magnets and the results of magnetic mesurements of the dipole magnets of the NSLS booster and storage rings. We interpret the magnetic measurements in terms of the magnet geometry and saturation characteristics. We discuss transport functions describing the linear and nonlinear focusing properties of the magnets, parametrized in terms of their curvature and fringe field length.

A Low Emittance Configuration for Spear

The quality of synchrotron radiation beams from SPEAR, in particular the brilliance of undulator radiation, can be improved significantly by reducing the emittance of the stored electron beam. A reduction of the horizontal emittance by a factor of 3.5 to a value of 130 nanometer-radians (nm-r) at 3 GeV has been achieved by using stronger focussing, mainly in the horizontal plane. The low emittance configuration also reduces the dispersion and vertical beta functions in the straight sections, making them more suitable for wigglers. The higher betatron tunes lead to a larger phase advance between the two kickers, which has to be corrected during injection by shunting current from some quadrupoles. The configuration was optimized within SPEAR hardware limitations and tested for dynamic aperture with the tracking program PATRICIA. After implementation of this scheme, beam was successfully injected and accumulated. The measured emittance of the stored beam was in agreement with calculations. Presently the configuration is being made operational.

Secondary Yield Enhancement from Current-Carrying Target

Monte Carlo calculations of relative yield of ¿-, K- and p- secondaries from cylindrical current-carrying production targets in high energy proton beams are presented. The results show that the expected focusing effect can increase the secondary intensity within the acceptance of a secondary beam by significant factors--in some cases two or more--with currents in the 15-to- 25 kA range. These currents are readily obtainable from pulsed power supplies. For dc operation currents of this magnitude appear possible from existing power supplies and for targets of small transverse dimensions such as 2 mm radius Ag.