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Title: THE Low-level Radio Frequency System for the superconducting cavities of National Synchrotron Light Source II

Abstract

A digital low-level radio frequency (LLRF) field controller has been developed for the storage ring of The National Synchrotron Light Source-II (NSLS-II). The primary performance goal for the LLRF is to support the required RF operation of the superconducting cavities with a beam current of 500mA and a 0.14 degree or better RF phase stability. The digital field controller is FPGA-based, in a standard format 19-inch/I-U chassis. It has an option of high-level control support with MATLAB running on a local host computer through a USB2.0 port. The field controller has been field tested with the high-power superconducting RF (SRF) at Canadian light Source, and successfully stored a high beam current of 250 mA. The test results show that required specifications for the cavity RF field stability are met. This digital field controller is also currently being used as a development platform for other functional modules in the NSLS-II RF systems.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
DOE - Office Of Science
OSTI Identifier:
1012580
Report Number(s):
BNL-94859-2011-CP
39KC02000; TRN: US1102322
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Conference
Resource Relation:
Conference: PAC 2011; New York, NY; 20110328 through 20110328
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BEAM CURRENTS; CAVITIES; COMPUTERS; FUNCTIONALS; LIGHT SOURCES; NSLS; PERFORMANCE; PHASE STABILITY; RF SYSTEMS; SPECIFICATIONS; STABILITY; STORAGE RINGS; SYNCHROTRONS; goal for the LLRF; cavity RF field; conducting PETRA cavity in the Booster; national synchrotron light source

Citation Formats

Ma, H., Rose, J., Holub, B., Cupolo, J., Oliva, J., Sikora, R., and Yeddulla, M.. THE Low-level Radio Frequency System for the superconducting cavities of National Synchrotron Light Source II. United States: N. p., 2011. Web.
Ma, H., Rose, J., Holub, B., Cupolo, J., Oliva, J., Sikora, R., & Yeddulla, M.. THE Low-level Radio Frequency System for the superconducting cavities of National Synchrotron Light Source II. United States.
Ma, H., Rose, J., Holub, B., Cupolo, J., Oliva, J., Sikora, R., and Yeddulla, M.. Mon . "THE Low-level Radio Frequency System for the superconducting cavities of National Synchrotron Light Source II". United States. doi:. https://www.osti.gov/servlets/purl/1012580.
@article{osti_1012580,
title = {THE Low-level Radio Frequency System for the superconducting cavities of National Synchrotron Light Source II},
author = {Ma, H. and Rose, J. and Holub, B. and Cupolo, J. and Oliva, J. and Sikora, R. and Yeddulla, M.},
abstractNote = {A digital low-level radio frequency (LLRF) field controller has been developed for the storage ring of The National Synchrotron Light Source-II (NSLS-II). The primary performance goal for the LLRF is to support the required RF operation of the superconducting cavities with a beam current of 500mA and a 0.14 degree or better RF phase stability. The digital field controller is FPGA-based, in a standard format 19-inch/I-U chassis. It has an option of high-level control support with MATLAB running on a local host computer through a USB2.0 port. The field controller has been field tested with the high-power superconducting RF (SRF) at Canadian light Source, and successfully stored a high beam current of 250 mA. The test results show that required specifications for the cavity RF field stability are met. This digital field controller is also currently being used as a development platform for other functional modules in the NSLS-II RF systems.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Mar 28 00:00:00 EDT 2011},
month = {Mon Mar 28 00:00:00 EDT 2011}
}

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  • The National Synchrotron Light Source-II (NSLS-II) is a new ultra-bright 3GeV 3rd generation synchrotron radiation light source. The performance goals require operation with a beam current of 500mA and a bunch current of at least 0.5mA. The position and timing specifications of the ultra-bright photon beam imposes a set of stringent requirements on the performance of radio frequency (RF) control. In addition, commissioning and staged installation of damping wigglers and insertion devices requires the flexibility of handling varying beam conditions. To meet these requirements, a digital implementation of the LLRF is chosen, and digital serial links are planned for themore » system integration. The first prototype of the controller front-end hardware has been built, and is currently being tested.« less
  • The National Synchrotron Light Source (NSLS), a 24 million dollar project under construction at Brookhaven National Laboratory (BNL), is a research facility dedicated to the production of synchrotron radiation. Synchrotron radiation is that radiation produced by the acceleration of charged particles at near the speed of light. This facility will provide a continuous spectrum of radiation from the vacuum ultraviolet to the hard x-ray range. The radiation will be highly intense, 100% polarized, extremely well collimated and will have a pulsed time structure. The radiation will be produced in two electron storage rings at energies of 700 MeV and 2.5more » GeV, respectively. A maximum of one ampere at 2 GeV, or one-half ampere at 2.5 GeV, of electron beam will be stored.« less
  • After three years of upgrading work, the Pohang Light Source-II (PLS-II) is now successfully operating. The final quantitative goal of PLS-II is a top-up user-service operation with beam current of 400 mA to be completed by the end of 2014. During the beam store test up to 400 mA in the storage ring (SR), it was observed that the vacuum pressure around the radio frequency (RF) window of the superconducting cavity rapidly increases over the interlock level limiting the availability of the maximum beam current storing. Although available beam current is enhanced by setting a higher RF accelerating voltage, it is bettermore » to keep the RF accelerating voltage as low as possible in the long time top-up operation. We investigated the cause of the window vacuum pressure increment by studying the changes in the electric field distribution at the superconducting cavity and waveguide according to the beam current. In our simulation, an equivalent physical modeling was developed using a finite-difference time-domain code. The simulation revealed that the electric field amplitude at the RF window is exponentially increased as the beam current increases, thus this high electric field amplitude causes a RF breakdown at the RF window, which comes with the rapid increase of window vacuum pressure. The RF accelerating voltage of PLS-II RF system was set to 4.95 MV, which was estimated using the maximum available beam current that works as a function of RF voltage, and the top-up operation test with the beam current of 400 mA was successfully carried out.« less
  • The vertical impedances of the preliminary designs of National Synchrotron Light Source II (NSLS-II) Mini Gap Undulators (MGU) are calculated by means of GdfidL code. The Transverse Mode Coupling Instability (TMCI) thresholds corresponding to these impedances are estimated using an analytically solvable model.
  • We have developed a subsystem capable of controlling stepping motors in a wide variety of vuv and x-ray spectrometers to be used at the National Sychrotron Light Source. The subsystem is capable of controlling up to 15 motors with encoder readback and ramped acceleration/deceleration. Both absolute and incremental encoders may be used in any mixture. Function commands to the subsystem are communicated via ASCII characters over an asynchronous serial link in a well-defined protocol in decipherable English. Thus the unit can be controlled via write statements in a high-level language. Details of hardware implementation will be presented.