SLS Internal Reports 2006

SLS-TME-TA-2006-0297

A. Streun

Minimum emittance superbend lattices ?

1-DEC-2004, 9 pages [PDF]

SLS-TME-TA-2006-0293

F. Le Pimpec, R. Ganter

Field Emission Dark Current of Technical Metallic Electrodes

submitted to NIM A, 15-SEP-2006, 18 pages [PDF]

In the framework of the Low Emittance Gun (LEG) project, high gradient ac- celeration of a low emittance electron beam will be necessary. In order to achieve this acceleration a -500 kV, 250 ns FWHM, pulse will be applied in between two electrodes. Those electrodes should sustain the pulsed field without arcing, must not outgass and must not emit electrons. Ion back bombardment, and dark current will be damageable to the electron source as well as for the low emittance beam. Electrodes of commercially available OFE copper, aluminium, stainless steel, tita- nium and molybdenum were tested following different procedures including plasma glow discharge cleaning.

SLS-TME-TA-2006-0291

Thomas Wehrli

Correlation between staggered BPM and RF-BPM readings: Calibration of their (linear) dependence and reliability of it

Seminararbeit ETH Zürich/PSI, 5-APR-2006, 18 pages [PDF] [DOC]

For the 07 beamline at Swiss Light Source, we calculated calibration factors for both XBPMs once by applying a symmetric bump at the BPMs and once with an anti-symmetric. The theoretical readings at the XBPMs were determined under consideration of optical influences that change all calibration factors about 10%. With that, we got a calibration factor of about 0.95 (symmetric) and 1.06 (anti-symmetric) for the first XBPM and 0.77 (symmetric) and 0.84 (anti-symmetric) for the second XBPM. As the symmetric and the anti-symmetric values are not consistent within their statistical errors of less than 0.1%, some relevant unconsidered systematic effects are described here. The biggest of them is more than 30 times bigger than the rest of our uncontrolled inaccuracies and noise, which limit the beam stability. An elimination of this effect therefore has a potential not only to make the calibration factors more consistent, but even to reduce the root-mean-square deviation of the beam position.

SLS-TME-TA-2006-0289

Christof Kraus

Finite Element-Time Domain (FETD) Simulation

Diplomarbeit ETH Zürich, 20-MAR-2006, 35 pages [PDF]

In dieser Arbeit konnte gezeigt werden, dass die Integration der Maxwell-Gleichungen mit der FETD-Methode durchführbar ist, und diese für tiefe Frequenzen sehr gute Resultate liefert. Es konnte am einfachen Beispiel des Einheitswürfels auch die Effekte vom h- und p-Refinement, sowie der Verkleinerung des Zeitschrittes untersucht werden. Es zeigte sich, dass auch bei den Maxwell-Gleichungen mit einem p-Refinement ein grosser Performance-Gewinn erzielt werden kann. Andererseits konnte an einem Beispiel gezeigte werden, dass die Verfeinerung des Meshes an Grenzen stossen kann, wo eine weitere Verfeinerung keine Reduktion des Fehlers zur Folge hat. Es hat sich auch gezeigt, dass für höhere Frequenzen mehr Aufwand betrieben werden muss. Spielen grössere Frequenzen eine bedeutende Rolle, muss das Mesh verfeinert, der Polynomgrad erhöht oder eine Kombination mit lokaler Verfeinerung des Netzes durchgeführt werden.

SLS-TME-TA-2006-0288

Marcus Wittberger

Finite-Element-Time-Domain (FETD) Simulation of charged Particles in a Cavity

Diplomarbeit ETH Zürich, 20-MAR-2006, 41 pages [PDF]

This diploma work is concerning with Finite-Element-Time-Domain (FETD) simulation of charged particles in a cavity. Mainly, a finite element framework FEMSTER and a parallel patricle framework IPPL were combined to a powerfull particle tracking program. FEMSTER, which is based on differential forms, provides finite elements of arbitrary polynomial degrees. The electromagnetic field is successfully evaluated by integratating the full Maxwell equations with a leap frog scheme. The validation of the particle propatation is not allready fully tested but can soon be expected.

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