ICALEPCS2011 - List of Authors (Himel, T.M.)

Paper

Title

Page

Changing Horses Mid-stream: Upgrading the LCLS Control System During Production Operations

574

S. L. Hoobler, R.P. Chestnut, S. Chevtsov, T.M. Himel, K.D. Kotturi, K. Luchini, J.J. Olsen, S. Peng, J. Rock, R.C. Sass, T. Straumann, R. Traller, G.R. White, S. Zelazny, J. Zhou
SLAC, Menlo Park, California, USA

The control system for the Linac Coherent Light Source (LCLS) began as a combination of new and legacy systems. When the LCLS began operating, the bulk of the facility was newly constructed, including a new control system using the Experimental Physics and Industrial Control System (EPICS) framework. The Linear Accelerator (LINAC) portion of the LCLS was repurposed for use by the LCLS and was controlled by the legacy system, which was built nearly 30 years ago. This system uses CAMAC, distributed 80386 microprocessors, and a central Alpha 6600 computer running the VMS operating system. This legacy control system has been successfully upgraded to EPICS during LCLS production operations while maintaining the 95% uptime required by the LCLS users. The successful transition was made possible by thorough testing in sections of the LINAC which were not in use by the LCLS. Additionally, a system was implemented to switch control of a LINAC section between new and legacy control systems in a few minutes. Using this rapid switching, testing could be performed during maintenance periods and accelerator development days. If any problems were encountered after a section had been switched to the new control system, it could be quickly switched back.

Slides TUCAUST04 [0.183 MB]

WEPMN032

Development of Pattern Awareness Unit (PAU) for the LCLS Beam Based Fast Feedback System

954

K.H. Kim, S. Allison, D. Fairley, T.M. Himel, P. Krejcik, D. Rogind, E. Williams
SLAC, Menlo Park, California, USA

LCLS is now successfully operating at its design beam repetition rate of 120 Hz, but in order to ensure stable beam operation at this high rate we have developed a new timing pattern aware EPICS controller for beam line actuators. Actuators that are capable of responding at 120 Hz are controlled by the new Pattern Aware Unit (PAU) as part of the beam-based feedback system. The beam at the LCLS is synchronized to the 60 Hz AC power line phase and is subject to electrical noise which differs according to which of the six possible AC phases is chosen from the 3-phase site power line. Beam operation at 120 Hz interleaves two of these 60 Hz phases and the feedback must be able to apply independent corrections to the beam pulse according to which of the 60 Hz timing patterns the pulse is synchronized to. The PAU works together with the LCLS Event Timing system which broadcasts a timing pattern that uniquely identifies each pulse when it is measured and allows the feedback correction to be applied to subsequent pulses belonging to the same timing pattern, or time slot, as it is referred to at SLAC. At 120 Hz operation this effectively provides us with two independent, but interleaved feedback loops. Other beam programs at the SLAC facility such as LCLS-II and FACET will be pulsed on other time slots and the PAUs in those systems will respond to their appropriate timing patterns. This paper describes the details of the PAU development: real-time requirements and achievement, scalability, and consistency. The operational results will also be described.

Poster WEPMN032 [0.430 MB]

Paper	Title	Page
TUCAUST04	Changing Horses Mid-stream: Upgrading the LCLS Control System During Production Operations	574
	S. L. Hoobler, R.P. Chestnut, S. Chevtsov, T.M. Himel, K.D. Kotturi, K. Luchini, J.J. Olsen, S. Peng, J. Rock, R.C. Sass, T. Straumann, R. Traller, G.R. White, S. Zelazny, J. Zhou SLAC, Menlo Park, California, USA
	The control system for the Linac Coherent Light Source (LCLS) began as a combination of new and legacy systems. When the LCLS began operating, the bulk of the facility was newly constructed, including a new control system using the Experimental Physics and Industrial Control System (EPICS) framework. The Linear Accelerator (LINAC) portion of the LCLS was repurposed for use by the LCLS and was controlled by the legacy system, which was built nearly 30 years ago. This system uses CAMAC, distributed 80386 microprocessors, and a central Alpha 6600 computer running the VMS operating system. This legacy control system has been successfully upgraded to EPICS during LCLS production operations while maintaining the 95% uptime required by the LCLS users. The successful transition was made possible by thorough testing in sections of the LINAC which were not in use by the LCLS. Additionally, a system was implemented to switch control of a LINAC section between new and legacy control systems in a few minutes. Using this rapid switching, testing could be performed during maintenance periods and accelerator development days. If any problems were encountered after a section had been switched to the new control system, it could be quickly switched back.
	Slides TUCAUST04 [0.183 MB]

WEPMN032	Development of Pattern Awareness Unit (PAU) for the LCLS Beam Based Fast Feedback System	954
	K.H. Kim, S. Allison, D. Fairley, T.M. Himel, P. Krejcik, D. Rogind, E. Williams SLAC, Menlo Park, California, USA
	LCLS is now successfully operating at its design beam repetition rate of 120 Hz, but in order to ensure stable beam operation at this high rate we have developed a new timing pattern aware EPICS controller for beam line actuators. Actuators that are capable of responding at 120 Hz are controlled by the new Pattern Aware Unit (PAU) as part of the beam-based feedback system. The beam at the LCLS is synchronized to the 60 Hz AC power line phase and is subject to electrical noise which differs according to which of the six possible AC phases is chosen from the 3-phase site power line. Beam operation at 120 Hz interleaves two of these 60 Hz phases and the feedback must be able to apply independent corrections to the beam pulse according to which of the 60 Hz timing patterns the pulse is synchronized to. The PAU works together with the LCLS Event Timing system which broadcasts a timing pattern that uniquely identifies each pulse when it is measured and allows the feedback correction to be applied to subsequent pulses belonging to the same timing pattern, or time slot, as it is referred to at SLAC. At 120 Hz operation this effectively provides us with two independent, but interleaved feedback loops. Other beam programs at the SLAC facility such as LCLS-II and FACET will be pulsed on other time slots and the PAUs in those systems will respond to their appropriate timing patterns. This paper describes the details of the PAU development: real-time requirements and achievement, scalability, and consistency. The operational results will also be described.
	Poster WEPMN032 [0.430 MB]