O. Singh

Storage ring development at the National Synchrotron Light Source

Beam monitoring systems and other electronic systems at the NSLS storage rings are described in detail. Both the VUV and X‐ray rings are discussed and applications, such as lithography, are proposed. (AIP)

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>>

Orbit stability improvement at the NSLS X-ray ring

We describe recent improvements in both the short and long-term orbit stability at the NSLS X-ray Ring. The short-term stability has been improved by increasing the gain and the bandwidth of the global harmonic feedback systems. The long-term horizontal orbit drift over the course of a fill has been reduced by including the RF-frequency in the orbit feedback. Work is in progress to further reduce orbit drift by compensating for thermally induced mechanical motions of the beam position monitors.

Real time global orbit feedback system for NSLS X-ray ring

The authors report on the design and commissioning of a real-time harmonic global orbit feedback system for the NSLS (National Synchrotron Light Source) X-ray ring. This system uses 8 pick-up electrode position monitors and 16 trim dipole magnets to eliminate 3 harmonic components of the orbit fluctuations. Because of the larger number of position monitors and trim magnets, the X-ray ring feedback system differs from VUV (vacuum ultraviolet) ring system in that the Fourier analysis and harmonic generation networks are comprised of MDAC (multiplying digital-to-analog converter) boards controlled by computer. The implementation of the global feedback system has resulted in a dramatic improvement in orbit stability, by more than a factor of five everywhere. Simultaneous operation of the global and several local bump feedback systems has been achieved.<<ETX>>

Automatic steering of X-ray beams from NSLS insertion devices using closed orbit feedback

By the middle of 1989, there will be five insertion devices installed in the NSLS (National Synchrotron Light Source) X-ray electron storage ring, X-ray beams from these devices will be stabilized by local automatic steering systems to reduce beam motion at the end of the beamline. Both the position of the source and the direction of the radiation will be controlled using beam position feedback to the closed orbit. Another system will be installed to stabilize the electron orbit for the LEGS Compton backscattering experiment. Each feedback system will employ at least one X-ray beam position detector; some will also utilize RF electron beam position monitors. Analog hardware with a digital interface has been designed and will be installed in the near future. A totally digital realization of the feedback controller is under consideration.<<ETX>>

Upgrade of beam steering system components and controls for the NSLS storage rings

The installation of the new insertion devices and new experiments on the NSLS (National Synchrotron Light Source) storage rings has increased the demand for better stability of the electron orbit. This, in turn, increased the demand for better stability and resolution as well as larger bandwidth of the orbit correction system. All of the orbit-correcting dipoles now have new low-hysteresis laminated steel cores. The magnets are excited by commercial wideband (1-kHz) current-regulated power supplies. The input circuits of the new power supplies permit a summation of analog inputs from orbit-stabilization systems with set-point inputs digitally controlled by the operator. The design of the new system is described, and its present performance is summarized.<<ETX>>

Orbit feedback at the NSLS

Abstract We discuss the design of global and local orbit feedback systems. Analog and digital implementations at the NSLS are described, as are the results of measurements characterizing performance.

Insertion device development in the X13 straight of the NSLS X-ray ring

On the NSLS X-ray storage ring, the X13 straight section and beamline have been used for insertion-device-related R&D since 1990. We will describe three important projects: the Prototype Small-Gap Undulator (PSGU), the In-Vacuum Undulator (IVUN), and the Time Varying Elliptically Polarized Wiggler (EPW). The PSGU has successfully operated with a vertical aperture of only 3 mm, with minimal reduction in electron beam lifetime. The EPW has successfully run during regular user operations while switching at either 2 Hz or 100 Hz, with no adverse effects on other experiments. The IVUN project is a collaboration between NSLS and Spring-8, and installation is scheduled for may 1997.

Orbit compensation for the time-varying elliptically polarized wiggler with switching frequency at 100 Hz

In October 1996, the elliptically polarized wiggler, installed in the X13 straight section of the NSLS X-ray ring, was commissioned at an operating frequency of 100 Hz. This wiggler generates circularly polarized photons in the energy range of 0.1 to 10 keV with AC modulation of polarization helicity. The vertical magnetic field is produced by a hybrid permanent magnet structure, and the horizontal magnetic field is generated by an electromagnet capable of switching at frequencies up to 100 Hz. Here, we discuss the compensation of the residual vertical and horizontal orbit motion utilizing a time-domain algorithm employing a function generator to drive trim coils at the wiggler ends, and the wideband high precision orbit measurement system of the X-ray ring. The residual orbit motion has been reduced to a level below 1 micron, and the device has been run in regular operations with no negative effect on other users.

Global orbit feedback utilizing analog and digital technologies

At the NSLS, an analog global orbit feedback system is used in regular operations, and a digital global orbit feedback system is available in machine physics studies on the X-Ray Ring. Here, we discuss the relative merits of utilizing analog and digital technology in orbit feedback. Results of experiments are reported characterizing the performance of our analog and digital systems when operated individually or together. We give our thoughts on plans for future development of the orbit feedback systems at the NSLS.