109314327
Fast Orbit Feedback and Beam Stability at the Swiss Light Source
A global, fast orbit feedback (FOFB) based on the digital beam position monitor (DBPM) system has been in user operation at the Swiss Light Source (SLS) since November 2003. The SVD‐based correction scheme acts at a sampling rate of 4 kHz using position information from all 72 DBPM stations and applying corrections with all 72 horizontal and 72 vertical corrector magnets. As a result, the FOFB successfully damps orbit distortions, which are mainly caused by ground and girder vibrations as well as the 3‐Hz booster crosstalk. It also allows fast and independent ID gap changes, which are completely transparent to all SLS users. With top‐up as a regular operation mode at SLS, global beam stability on a μm‐level has been achieved from days to milliseconds.
54596016
SLS: Pushing the Envelope Based on Stability
The Swiss Light Source (SLS) is a synchrotron radiation user facility (2000 users/year, 18 beamlines, 5000 hrs/year) in operation at Paul Scherrer Institut (PSI) since 2001. Figure 1 presents a schematic view.
45605429
THE EVOLUTION OF THE DELTA CONTROL SYSTEM
Since January 1999 the Dortmunder Elektronen Testspeicherring Anlage (DELTA) control system has changed from a non-standard hand-made system to the standard Experimental Physics and Industrial Control System (EPICS) [1]. The complete 80 MeV LINAC and transfer-line, the asymmetric 5.5 T multipole wiggler magnet (SAW) and main parts of the 1.5 GeV electron storage ring are now under EPICS control. Additional hardware upgrades like a fast 100baseTX/FX Ethernet network, Linux-PCs, PowerPC-IOCs, and reengineered device I/O-interface cards have been installed. Moreover, a self-made VME DSP-board is in the final test phase to control the booster ramping process. Generic stream device drivers for the IEEE/GPIB and CAN fieldbusses have been developed and have already been in use for one year [2]. The number of high level software tools for data acquisition and evaluation as well as for remote device control and complex software feedback is increasing continuously. The availability of a wide variety of interfaces to the EPICS Channel Access (CA) protocol makes it possible to include state of the art software platforms and architectures like the CORBA middleware, Java, Delphi, Tcl/Tk etc. very easily. Furthermore, the integration of complex simulation, design and modeling tools together with database archiving and Web-based accelerator monitoring is in progress.
172132608
APPLICATION OF A 5 GSPS ANALOGUE RING SAMPLING CHIP FOR LOW-COST SINGLE-SHOT BPM SYSTEMS
The obtained test results indicate that DRS-based BPM electronics provide sufficient resolution e.g. for common transfer line BPMs. Other system characteristics like linearity and temperature drift as well as options for their in-situ measurement and FPGA-based periodic self-calibration are presently being investigated. The next chip version “DRS4” is expected to be available at PSI in a 10k quantity until fall 2008, with higher bandwidth, on-chip PLL, smaller chip size with improved grounding, and smaller AC bandwidth variations of the sampling cells. Further resolution improvements e.g. for stripline BPMs are possible by using the DRS4, by advanced amplitude fit ABSTRACT
55384087
First Experience with the Superconducting Asymmetric Wiggler of the DELTA Facility
The superconducting asymmetric wiggler (SAW) is a unique insertion device operated at the DELTA facility. This multipole wiggler magnet with 21 poles provides the possibility of both symmetric operation up to 2.8 T and asymmetric operation up to 5.3 T, featuring the possibility to produce circular polarized photons of about 8 keV in a 1.5 GeV storage ring. This paper will give a detailed description of the device itself, and will further describe the first results of the operation of this wiggler in the storage ring.
53377974
COMMISSIONING AND OPERATION OF THE SLS FAST ORBIT FEEDBACK
The SLS Fast Orbit Feedback (FOFB) was successfully commissioned in 2003 [1]. Since November 2003 it runs during user operation of the SLS. Taking into account 72 Digital Beam Position Monitors (DBPMs), the FOFB applies SVD-based global orbit corrections for 72 horizontal (x) and 72 vertical (y) correctors at a rate of 4 kHz, compared to 0.5 Hz for the Slow Orbit Feedback (SOFB) that was used so far. While the SOFB was important for the elimination of orbit drifts due to temperature changes and slowly moving insertion device (ID) gaps, the FOFB is also able to damp orbit oscillations that are caused by fast changes of ID gaps or magnets, by ground and girder vibrations, 3 Hz booster crosstalk and power supply noise. This report presents experience from commissioning and user operation of the FOFB.
117757554
Advanced numerical methods in astrophysical fluid dynamics
Computational gas dynamics has become a prominent research field both in astrophysics and cosmology. In the first part of this review we intend to briefly describe several of the numerical methods used in this field, discuss their range of application and present strategies for converting conditionally-stable numerical methods into unconditionally-stable solution procedures. The underlying aim of the conversion is to enhance the robustness and unification of numerical methods and subsequently enlarge their range of applications considerably. In the second part Fabian Heitsch presents and discusses the implementation of a time-explicit MHD Boltzmann solver.