J. H. Wang

A closed orbit measurement with the NSRL BPM system

The beam position monitor system (BPM) of NSRL electron storage ring have a resolution of 10 microns with an accuracy of 50 microns, which is adequate fix beam position measurement and the closed orbit correction. The paper describes both of the BPM system and the closed orbit measurement.

The updated BPM system of HLS

The operation of the updated BPM system of HLS and the VXI-based application of LabVIEW as well as Network technic in the NSRL phase II project, are introduced here. The Bergoz BPM modules and the modular VXI measurement instruments are adopted for data measurement and acquirement, in order to provide stable and credible performance. The LabVIEW development environment of VXI-based, which is adopted in our project, not only provides good hardware controls, but also promotes the development efficiency. The measured data is fed back to correct closed orbit of the storage ring in constant time interval. At the same time, another copy of the measured data is sent to an independent data-server to be recorded. The BPM system now works with a precision not greater than 10 /spl mu/m, and a resolution about 1 /spl mu/m.

Development of Measurement and Transverse Feedback System at HLS

In order to cure and damp coupled bunch (CB) instabilities caused by the high order modes (HOMs) of the RF cavity and the resistive wall impedance of the Ring vacuum chamber. HOMs are ineluctable during the operation of the accelerator. An observer system characterized by bunch by bunch measurement of transverse β oscillation and longitudinal synchrotron phase oscillation has been constructed and commissioned at Hefei Light Source (HLS) [1, 2]. A transverse bunch-by-bunch feedback system is under construction. The design and development of the observe systems, as well as diagnostics results of machine instabilities are presented in this paper.

The Study of New Signal Processing Technique in Photon Beam Position Monitors

A log-ratio signal processing technique in photon beam position monitors (PBPMs) was presented in this paper. The main performances (e.g. sensitivity, position offset and linearity range) of split PBPM and two-wire PBPM were analyzed. An inexpensive logarithmic and log-ratio amplifier chip (LOG112) that can measure currents from 0.1nA to 3.5mA was used in circuits.

Several new beam measurement systems for HLS

This paper describes several new beam instruments for Hefei light source (HLS). These new beam instruments include a tuning measurement system to measure the beam tune and chromaticity, a DCCT measurement system to measure the beam DC current and beam life, and a closed orbit measuring system to measure the beam position. Some applications of these measurement systems and their measurement results are presented.

The Measurement of Tune and Phase Space at HLS

Tune and phase space online monitor at the electronic storage ring of Hefei Light Source (HLS) has been implemented by using Turn-by-turn Beam Position Monitor System (TBT System). In this paper, we compare a number of methods employed to compute tune and deals with choosing the best fitting method for our online tune computing. We can compute and display tune online, at the same time, record beam tracks on the transverse phase space by using turn-by-turn beam position data at two differently-located beam-position-monitor electrodes. With these instruments we can precisely and attractive study machine instabilities.

A Method to Calibrate Beam Position Monitor at HLS 200 MeV Linac

In order to improve injection efficiency of HLS 200Mev LINAC, we redesign a new strip line beam position monitor system, which is consisted of a strip line structure and a signal processing system. We decide on an online calibration method based on beam to find out the geometry centre displacement and relative gain offset. Before the BPM testing bench has been prepared, we make a simulation based on the model accounted for all factors influencing signal amplitudes and get the calibrating results. At last, we analyze the nonlinearity effect on the calibration results.

Design and simulation of beam position monitor for 200 MeV linac in HLS

In order to improve injection efficiency of HLS (Hefei Light Source), an appropriate BPM (beam position monitor) is needed to provide the transverse positions and longitudinal phases of linac and transfer line beam. The original stripline BPM for HLS Linac, which is 20.8 degrees in azimuthal angle and has a poor performance in coupling signals on electrodes, is redesigned and calculated through Mafia and CST Microwave Studio. The new stripline BPM structure, which is 60 degrees and 183.8 mm long, has a better performance in time response, spectrum, linearity and sensitivity when a beam passes by. Lastly, the position resolution and time resolution of the new structure is theoretically calculated, which meets the requirement of HLS Linac and transfer line.

Development and Application of Bunch-By-Bunch Measurement System of HLS

This paper is intended to present the newly implemented wideband (100MHz) bunch oscillation measurement system, which is in nature a different method from the narrow-band (< 5MHz) facilities employed before. Basic formalism and implementation details of the system is introduced to illustrate the function of observing coupled bunch instabilities in time and frequency domain. The designed function includes detecting of transverse oscillation, synchrotron phase oscillation, as well as bunch filling pattern. Some diagnostics results of machine instabilities and application of this system are also discussed.

HLS Turn-by-Turn System and its Application

Measurement principles and analysis of Turn-by-Turn beam position monitor system at Hefei Light Source (HLS) are presented in this paper. In emphases, several typical applications are presented here, which include the commissioning of upgraded injection system on HLS storage, monitoring of transientν transientν transientν transientν transientν transientν transientν transientν transientν transientν and damping time of storage ring, beam instability in injection, as well as experiments of low frequency feedback system. Precise analyses of experimental results offer some conclusions, which are consistent with theoretical expectations. The system plays an important role in study of beam instability and improvement of machine performance.