Fast Feedback System for CEBAF.
Fast Feedback System for CEBAF.

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Publisher:

Published: 1995

Total Pages:

ISBN-13:

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A fast feedback system based on concepts of modern control theory has been implemented in the CEBAF Control System to stabilize various machine parameters. The continuous wave operation of CEBAF requires that parameters such as beam energy and position are stabilized against fast fluctuations. The beam energy must be stabilized against fast gradient and phase fluctuations in the RF accelerating system. This fast feedback system currently operates at 60 Hz rate and is integrated with EPICS. The mathematical model of the system for various feedback loops is expressed in state space formalism. The design of control law and simulation of closed-loop system response is performed using MatlabTM and SimulinkTM. This paper describes the process of designing control algorithms, implementation of the fast feedback system and operational experience with this system at CEBAF. The performance of this feedback system, while operating at much higher rates with high closed loop gain, can be enhanced by continually performing on-line identification of the system from the input and output data. System identification is the process of developing or improving an analytically derived mathematical representation of a physical system using experimental data. The current status of this feature is presented.

Advances in Cryogenic Engineering
Advances in Cryogenic Engineering

Author: Peter Kittel

Publisher: Springer Science & Business Media

Published: 2013-11-11

Total Pages: 2054

ISBN-13: 1475790473

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The Oregon Convention Center, Portland, Oregon, was the venue for the 1997 Cryogenic Engineering Conference. The meeting was held jointly with the International Cryogenic Materials Conference. John Barclay, of the University of Victoria, and David Smathers, of Cabot Performance Materials, were conference chairmen. Portland is the home of Northwest Natural Gas, a pioneer in the use of liquid natural gas, and Portland State University, where cryogenic research has long been conducted. The program consisted of 350 CEC papers, considerable more than CEC-95. This was the largest number of papers ever submitted to the CEC. Of these, 263 papers are published here, in Volume 43 of Advances in Cryogenic Engineering. Once again the volume is published in two books. CEC PAPER REVIEW PROCESS Since 1954 Advances in Cryogenic Engineering has been the archival publication of papers presented at the biennial CEC!ICMC conferences. The publication includes invited, unsolicited, and government sponsored research papers in the research areas of cryogenic engineering and applications. All of the papers published must (1) be presented at the conference, (2) pass the peer review process, and (3) report previously unpublished theoretical studies, reviews, or advances in cryogenic engineering.

The CEBAF Control System
The CEBAF Control System

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Publisher:

Published: 1995

Total Pages: 4

ISBN-13:

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CEBAF has recently upgraded its accelerator control system to use EPICS, a control system toolkit being developed by a collaboration among laboratories in the US and Europe. The migration to EPICS has taken place during a year of intense commissioning activity, with new and old control systems operating concurrently. Existing CAMAC hardware was preserved by adding a CAMAC serial highway link to VME; newer hardware developments are now primarily in VME. Software is distributed among three tiers of computers: first, workstations and X terminals for operator interfaces and high level applications; second, VME single board computers for distributed access to hardware and for local control processing; third, embedded processors where needed for faster closed loop operation. This system has demonstrated the ability to scale EPICS to controlling thousands of devices, including hundreds of embedded processors, with control distributed among dozens of VME processors executing more than 125,000 EPICS database records. To deal with the large size of the control system, CEBAF has integrated an object oriented database, providing data management capabilities for both low level I/O and high level machine modeling. A new callable interface which is control system independent permits access to live EPICS data, data in other Unix processes, and data contained in the object oriented database.

A Prototype Fast Feedback System for Energy Lock at CEBAF.
A Prototype Fast Feedback System for Energy Lock at CEBAF.

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Publisher:

Published: 1995

Total Pages: 4

ISBN-13:

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The beam energy at CEBAF must be controlled accurately against phase and gradient fluctuations in RF cavities in order to achieve a 2.5 x 10−5 relative energy spread. A prototype fast feedback system based on the concepts of Modern Control Theory has been implemented in the CEBAF control system to function as an energy lock. Measurements performed during the pulsed mode operations indicate presence of noise components at 4 Hz and 12 Hz on beam energy. This fast feedback prototype operates at 60 Hz rate and is integrated with EPICS. This paper describes the implementation of the fast feedback prototype, and operational experience with this system at CEBAF. 5 refs., 3 figs.

Overview of CEBAF Operations and SRF-related Activities at Jefferson Lab
Overview of CEBAF Operations and SRF-related Activities at Jefferson Lab

Author:

Publisher:

Published: 1999

Total Pages:

ISBN-13:

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The Jefferson Lab nuclear physics accelerator, CEBAF, continues to reliably deliver polarized CW electron beams with energy in the range of 1--5.5 GeV. The 330 installed 1,500 MHz SRF cavity systems perform solidly, contributing a small fraction of the machine downtime. The 5-pass energy capability has been pushed to near 6 GeV by application of in situ helium processing to almost all of the cavities. New operational tools have been developed and deployed which allow the operators to quickly reconfigure the linacs for optimal performance under various energy and beamloading conditions. Plans are being developed for upgrading CEBAF to 12 GeV. This requires a new cryomodule design and use of 5.5 recirculations for the top energy. Subsystem development is underway on a 7-cell cavity, new zero-backlash tuner, improved magnetic shielding, and an arc-free waveguide rf feed, as well as a new cryomodule mechanical system. Significant facility changes have been made in preparation for this work. A new rf control system will also be required. In addition to the successful nuclear physics program, the JLab FEL produced a world-record 1.7 kW CW in the infrared. An upgrade program is ready to begin. Significant efforts have also been directed in support of APT and RIA, as well as collaborations related to cavity fabrication and processing techniques.