Adaptive cascaded beam based feedback at the SLC
01 May 1993-Vol. 930517, pp 2106-2108
TL;DR: In this article, the SLAC Linear Collider has a total of twenty-four beam-steering feedback loops used to keep the electron and positron beams on their desired trajectories, seven of which measure and control the same beam as it proceeds down the linac through the arcs to the final focus.
Abstract: The SLAC Linear Collider now has a total of twenty-four beam-steering feedback loops used to keep the electron and positron beams on their desired trajectories. Seven of these loops measure and control the same beam as it proceeds down the linac through the arcs to the final focus. Ideally each loop should correct only for disturbances that occur between it and the immediate upstream loop. In fact, in the original system each loop corrected for all upstream disturbances. This resulted in undesirable overcorrection and ringing. We added MIMO (Multiple Input Multiple Output) adaptive noise cancellers to separate the signal we wish to correct from disturbances further up stream. This adaptive control improved performance in the 1992 run. >
Citations
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01 May 1995
TL;DR: The Stanford Linear Collider (SLC) as mentioned in this paper is the only high-energy e/sup +/e/sup -/ linear collider in the world that produces high intensity, submicron sized, polarized beams at a single interaction point.
Abstract: The Stanford Linear Collider (SLC) is the first and only high-energy e/sup +/e/sup -/ linear collider in the world. Its most remarkable features are high intensity, submicron sized, polarized (e/sup -/) beams at a single interaction point. The main challenges posed by these unique characteristics include machine-wide emittance preservation, consistent high intensity operation, polarized electron production and transport, and the achievement of a high degree of beam stability on all time scales. In addition to serving as an important machine for the study of Z/sup 0/ boson production and decay using polarized beams, the SLC is also an indispensable source of hands-on experience for future linear colliders. Each new year of operation has been highlighted with a marked improvement in performance. The most significant improvements for the 1994-95 run include new low impedance vacuum chambers for the damping rings, an upgrade to the optics and diagnostics of the final focus systems, and a higher degree of polarization from the electron source. As a result, the average luminosity has nearly doubled over the previous year with peaks approaching 10/sup 30/ cm/sup -2/ s/sup -1/ and an 80% electron polarization at the interaction point. These developments as well as the remaining identifiable performance limitations will be discussed.
18Â citations
Posted Content•
TL;DR: The Stanford Linear Collider (SLC) was the first prototype of a new type of accelerator, the electron-positron linear collider as mentioned in this paper, and many years of dedicated effort were required to understand the physics of this new technology and to develop the techniques for maximizing performance.
Abstract: The Stanford Linear Collider (SLC) was the first prototype of a new type of accelerator, the electron-positron linear collider. Many years of dedicated effort were required to understand the physics of this new technology and to develop the techniques for maximizing performance. Key issues were emittance dilution, stability, final beam optimization and background control. Precision, non-invasive diagnostics were required to measure and monitor the beams throughout the machine. Beam-based feedback systems were needed to stabilize energy, trajectory, intensity and the final beam size at the interaction point. A variety of new tuning techniques were developed to correct for residual optical or alignment errors. The final focus system underwent a series of refinements in order to deliver sub-micron size beams. It also took many iterations to understand the sources of backgrounds and develop the methods to control them. The benefit from this accumulated experience was seen in the performance of the SLC during its final run in 1997-98. The luminosity increased by a factor of three to 3*10**30 and the 350,000 Z data sample delivered was nearly double that from all previous runs combined.
16Â citations
Proceedings Article•
27 Jul 1997TL;DR: A new architecture for accelerator tuning that combines heuristic and knowledge based methods with traditional approaches to control is discussed, which is distributed and hierarchical to utilize parallel problem-solving in the face of time-sensitive control requirements.
Abstract: This paper discusses a new architecture for accelerator tuning that combines heuristic and knowledge based methods with traditional approaches to control. Control of particle accelerators requires a hybrid architecture, which includes methodologies for planning, intelligent search, and pattern recognition. Control is distributed and hierarchical to utilize parallel problem-solving in the face of time-sensitive control requirements and to decompose complex control problems into more manageable subtasks. For perspective, we discuss past attempts at accelerator control and why these attempts left many issues unresolved. We describe the details of our control architecture along with its motivation. We then report the results of deploying and testing it at two accelerator facilities. This paper ends with a discussion of the commercial importance of this work.
15Â citations
01 Jan 1999
TL;DR: In this paper, the authors proposed feedback systems for stable operation of a linear collider, providing a cost-effective method for relaxing tight tolerances for the next linear Collider (NLC).
Abstract: Feedback systems are essential for stable operation of a linear collider, providing a cost-effective method for relaxing tight tolerances. In the Stanford Linear Collider (SLC), feedback controls beam parameters such as trajectory, energy, and intensity throughout the accelerator. A novel dithering optimization system which adjusts final focus parameters to maximize luminosity contributed to achieving record performance in the 1997-98 run. Performance limitations of the steering feedback have been investigated, and improvements have been made. For the Next Linear Collider (NLC), extensive feedback systems are planned as an integral part of the design. Feedback requirements for JLC (the Japanese Linear Collider) are essentially identical to NLC; some of the TESLA requirements are similar but there are significant differences. For NLC, algorithms which incorporate improvements upon the SLC implementation are being prototyped. Specialized systems for the damping rings, RF and interaction point will operate at high bandwidth and fast response. To correct for the motion of individual bunches within a train, both feedforward and feedback systems are planned. SLC experience has shown that feedback systems are an invaluable operational tool for decoupling systems, allowing precision tuning, and providing pulse-to-pulse diagnostics. Feedback systems for the NLC will incorporate the key SLC features and the benefits of advancing technologies.
12Â citations
01 May 1995
TL;DR: In this paper, the response of various feedback loops to these errors is measured and analyzed in an attempt to improve performance at the Stanford Linear Collider (SLC) in order to improve the performance.
Abstract: Many feedback loops are used at the Stanford Linear Collider (SLC) to control the orbit and energy of particle beams. Problems with corrector magnet slew rates, actuator calibrations, and computation of the beam transport matrix between loops have resulted in operation of many SLC feedback loops at lower than design gain. The response of various feedback loops to these errors is measured and analyzed in an attempt to improve performance.
11Â citations
References
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Book•
01 Jan 1985TL;DR: This chapter discusses Adaptive Arrays and Adaptive Beamforming, as well as other Adaptive Algorithms and Structures, and discusses the Z-Transform in Adaptive Signal Processing.
Abstract: GENERAL INTRODUCTION. Adaptive Systems. The Adaptive Linear Combiner. THEORY OF ADAPTATION WITH STATIONARY SIGNALS. Properties of the Quadratic Performance Surface. Searching the Performance Surface. Gradient Estimation and Its Effects on Adaptation. ADAPTIVE ALGORITHMS AND STRUCTURES. The LMS Algorithm. The Z-Transform in Adaptive Signal Processing. Other Adaptive Algorithms and Structures. Adaptive Lattice Filters. APPLICATIONS. Adaptive Modeling and System Identification. Inverse Adaptive Modeling, Deconvolution, and Equalization. Adaptive Control Systems. Adaptive Interference Cancelling. Introduction to Adaptive Arrays and Adaptive Beamforming. Analysis of Adaptive Beamformers.
5,645Â citations
01 May 1995
TL;DR: The Stanford Linear Collider (SLC) as mentioned in this paper is the only high-energy e/sup +/e/sup -/ linear collider in the world that produces high intensity, submicron sized, polarized beams at a single interaction point.
Abstract: The Stanford Linear Collider (SLC) is the first and only high-energy e/sup +/e/sup -/ linear collider in the world. Its most remarkable features are high intensity, submicron sized, polarized (e/sup -/) beams at a single interaction point. The main challenges posed by these unique characteristics include machine-wide emittance preservation, consistent high intensity operation, polarized electron production and transport, and the achievement of a high degree of beam stability on all time scales. In addition to serving as an important machine for the study of Z/sup 0/ boson production and decay using polarized beams, the SLC is also an indispensable source of hands-on experience for future linear colliders. Each new year of operation has been highlighted with a marked improvement in performance. The most significant improvements for the 1994-95 run include new low impedance vacuum chambers for the damping rings, an upgrade to the optics and diagnostics of the final focus systems, and a higher degree of polarization from the electron source. As a result, the average luminosity has nearly doubled over the previous year with peaks approaching 10/sup 30/ cm/sup -2/ s/sup -1/ and an 80% electron polarization at the interaction point. These developments as well as the remaining identifiable performance limitations will be discussed.
18Â citations
Proceedings Article•
27 Jul 1997TL;DR: A new architecture for accelerator tuning that combines heuristic and knowledge based methods with traditional approaches to control is discussed, which is distributed and hierarchical to utilize parallel problem-solving in the face of time-sensitive control requirements.
Abstract: This paper discusses a new architecture for accelerator tuning that combines heuristic and knowledge based methods with traditional approaches to control. Control of particle accelerators requires a hybrid architecture, which includes methodologies for planning, intelligent search, and pattern recognition. Control is distributed and hierarchical to utilize parallel problem-solving in the face of time-sensitive control requirements and to decompose complex control problems into more manageable subtasks. For perspective, we discuss past attempts at accelerator control and why these attempts left many issues unresolved. We describe the details of our control architecture along with its motivation. We then report the results of deploying and testing it at two accelerator facilities. This paper ends with a discussion of the commercial importance of this work.
15Â citations
01 Jan 1999
TL;DR: In this paper, the authors proposed feedback systems for stable operation of a linear collider, providing a cost-effective method for relaxing tight tolerances for the next linear Collider (NLC).
Abstract: Feedback systems are essential for stable operation of a linear collider, providing a cost-effective method for relaxing tight tolerances. In the Stanford Linear Collider (SLC), feedback controls beam parameters such as trajectory, energy, and intensity throughout the accelerator. A novel dithering optimization system which adjusts final focus parameters to maximize luminosity contributed to achieving record performance in the 1997-98 run. Performance limitations of the steering feedback have been investigated, and improvements have been made. For the Next Linear Collider (NLC), extensive feedback systems are planned as an integral part of the design. Feedback requirements for JLC (the Japanese Linear Collider) are essentially identical to NLC; some of the TESLA requirements are similar but there are significant differences. For NLC, algorithms which incorporate improvements upon the SLC implementation are being prototyped. Specialized systems for the damping rings, RF and interaction point will operate at high bandwidth and fast response. To correct for the motion of individual bunches within a train, both feedforward and feedback systems are planned. SLC experience has shown that feedback systems are an invaluable operational tool for decoupling systems, allowing precision tuning, and providing pulse-to-pulse diagnostics. Feedback systems for the NLC will incorporate the key SLC features and the benefits of advancing technologies.
12Â citations
01 Jun 1992-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: A new feedback system has been developed that stabilizes the SLC beams at many locations and has measurably improved the performance of the accelerator.
Abstract: A new feedback system has been developed that stabilizes the SLC beams at many locations. The feedback loops are designed to sample and correct at the repetition rate of the accelerator. Each loop can be distributed across several INTEL 80386 microprocessors that control the SLC hardware. A new communications system, KISNET, has been developed to pass data between the microprocessors at this rate. The software is written using the state space formalism of digital control theory and is database driven. This allows a new feedback loop to be implemented by setting up the on-line database and perhaps installing a communications link. Eighteen such loops have now been implemented and this has measurably improved the performance of the accelerator.
11Â citations