J. Galayda

Real time harmonic closed orbit correction

Abstract We discuss several schemes for improving the stability of the closed orbit, by implementing a feedback system based upon harmonic analysis of both the orbit movements and the correction magnetic fields. The harmonic feedback system corrects the Fourier components of the orbit nearest to the betatron tune. Such a system may provide a significant improvement in orbit stability for all beamlines, using simpler electronics than required for an array of local bump feedback systems. Experiments based upon these schemes are in progress at the NSLS.

FEL development at the Advanced Photon Source

Construction of a single-pass free-electron laser (FEL) based on the self-amplified spontaneous emission (SASE) mode of operation is nearing completion at the Advanced Photon Source (APS) with initial experiments imminent. The APS SASE FEL is a proof-of-principle fourth-generation light source. As of January 1999 the undulator hall, end-station building, necessary transfer lines, electron and optical diagnostics, injectors, and initial undulators have been constructed and, with the exception of the undulators, installed. All preliminary code development and simulations have also been completed. The undulator hall is now ready to accept first beam for characterization of the output radiation. It is the project goal to push towards full FEL saturation, initially in the visible, but ultimately to UV and VUV, wavelengths.

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.

The Advanced Photon Source

The Advanced Photon Source (APS) is a 7-GeV third-generation synchrotron radiation storage ring and full-energy positron injector. Construction project funding began in 1989, and ground breaking took place on 5 May 1990. Construction of all accelerator facilities was completed in January 1995 and storage ring commissioning is underway. First observation of X-rays from a bending magnet source took place on 26 March 1995. Nearly all performance specifications of the injector have been reached, and first observations indicate that the reliability, dynamic aperture, emittance, and orbit stability in the storage ring are satisfactory. Observation of radiation from the first of 20 insertion device beamlines is scheduled for October 1995. Start of regular operations is expected to take place well before the APS Project target date of December 1996.

The NSLS Magnet System

An overview of the National Synchrotron Light Source magnetic component system is given. Design parameters, construction methods and measurement procedures for the dipoles and multipole are presented for the storage rings and booster synchrotron.

The Advanced Photon Source low-energy undulator test line

There are a number of fully commissioned 3rd-generation synchrotron light sources in the world today. So far they have met the demanding requirements of the user community; however, there is always a desire to go beyond what is presently available or even desirable. The Advanced Photon Source (APS) Low-Energy Undulator Test Line (LEUTL) was conceived to address the advancement of synchrotron light sources. The LEUTL uses the existing APS linac and a low-emittance electron gun, and by means of measurements of the beam and generated light, will test new and innovative undulators and push the technology and physics of single-pass, coherent light sources. The design and status of the LEUTL are described along with its immediate capabilities and those planned for the future.

Real time closed orbit correction system

A global closed-orbit feedback experiment based upon a real-time harmonic analysis of both the orbit movement and the correction magnetic fields is described. The harmonic feedback system was constructed and tested on the 750 MeV vacuum ultraviolet ring of the NSLS (National Synchrotron Light Source) and implemented on a real-time basis using relatively simple electronics. The feedback forces the coefficients of a few harmonics near the betatron tune to vanish and significantly improves the global orbit stability. The result of the experiment in the ring using four detectors and four trims, in which maximum observed displacement was reduced by a factor of between three and four, is presented.<<ETX>>

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.

Progress report on the LCLS XFEL at SLAC

The Linac Coherent Light Source (LCLS) Project will be an x-ray free-electron laser. It is intended to produce pulses of 800-8,000 eV photons. Each pulse, produced with a repetition frequency of up to 120 Hz, will provide >1012 photons within a duration of less than 200 femtoseconds. The project employs the last kilometer of the SLAC linac to provide a low-emittance electron beam in the energy range 4-14 GeV to a single undulator. Two experiment halls, located 100 m and 350 m from the undulator exit, will house six experiment stations for research in atomic/molecular physics, pump-probe dynamics of materials and chemical processes, x-ray imaging of clusters and complex molecules, and plasma physics. Engineering design activities began in 2003, and the project is to be completed in the middle of 2010. The project design permits straightforward expansion of the LCLS to multiple undulators.

Observation of a self-colliding beam

A single beam of accelerated deuterium ions, D+2, of 108 keV, injected into a highly inhomogeneous magnetic field, decreasing quadratically with the radial distance from the center, was made to collide head‐on with itself. The trajectory of the ’’self‐colliding beam’’ is a precessing figure 8, with the ions moving clockwise in both (upper and lower) loops and colliding head‐on in the center.