EPAC08 - List of Authors (Lundgren, S. A.)

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Lundgren, S. A.

Paper	Title	Page
MOPC095	Mechanical and Thermal Prototype Testing for a Rotatable Collimator for the LHC Phase II Collimation Upgrade	286
	J. C. Smith, J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz SLAC, Menlo Park, California
	The Phase II upgrade to the LHC collimation systems calls for complementing the 30 high robust Phase I graphite collimators with 30 high Z, low impedance Phase II collimators. The design for the collimation upgrade has not been finalized. One option is to use metallic rotatable collimators and this design will be discussed here. The Phase II collimators must be robust in various operating conditions and accident scenarios. A series of prototype collimator jaws have been tested for both mechanical and thermal compliance with the design goals. Collimator jaw shape after thermal expansion benchtop tests were compared to ANSYS simulation results. Mechanical tests were also performed to demonstrate fabrication precision and collimator movement operation as designed.
MOPC096	Design of a Rotatable Copper Collimator for the LHC Phase II Collimation Upgrade	289
	J. C. Smith, J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz SLAC, Menlo Park, California L. Lari EPFL, Lausanne
	The Phase II upgrade to the LHC collimation systems calls for complementing the 30 high robust Phase I graphite collimators with 30 high Z, low impedance Phase II collimators. The design for the collimation upgrade has not been finalized. One option is to use metallic rotatable collimators and this design will be discussed here. The Phase II collimators must be robust in various operating conditions and accident scenarios. Design issues include: Collimator jaw deflection due to heating and sagita must be small when operated in the steady state condition, Collimator jaws must withstand transitory periods of high beam impaction with no permanent damage, Jaws must recover from accident scenario where up to 8 full intensity beam pulses impact on the jaw surface and The beam impedance contribution due to the collimators must be small to minimize coherent beam instabilities. The current design will be presented.
TUPP073	Bench-top Impedance Measurements for a Rotatable Copper Collimator for the LHC Phase II Collimation Upgrade	1703
	J. C. Smith, K. L.F. Bane, J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz, C.-K. Ng, L. Xiao SLAC, Menlo Park, California
	The Phase II upgrade to the LHC collimation system calls for complementing the 30 high robust Phase I graphite collimators with 30 high Z, low impedance Phase II collimators. The design for the collimation upgrade has not been finalized. One option is to use metallic rotatable collimators and this design will be discussed here. Simulations have been performed in MAFIA to study both the resistive wall and geometric impedance contributions of our rotatable collimator design. Benchtop stretched coil probe impedance measurements have also been performed on prototype components to directly measure the low frequency impedance contributions. The design also calls for an RF contact interface at the jaw end. This contact resistance must be a small fraction of a milliohm in order to limit transverse impedance. DC resistance measurements in a custom built test chamber have been performed to test the performance of various metal pairs and surface coatings.
WEPP072	Evaluation of Beam Losses and Energy Deposition for A Possible Phase II Design for LHC Collimation	2686
	L. Lari, R. W. Assmann, C. Bracco, M. Brugger, F. Cerutti, A. Ferrari, M. Mauri, S. Redaelli, L. Sarchiapone, V. Vlachoudis, Th. Weiler CERN, Geneva J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz, J. C. Smith SLAC, Menlo Park, California L. Lari EPFL, Lausanne
	The LHC beams are designed to have high stability and to be stored for many hours. The nominal beam intensity lifetime is expected to be of the order of 20h. The Phase II collimation system has to be able to handle particle losses in stable physics conditions at 7 TeV in order to avoid beam aborts and to allow correction of parameters and restoration to nominal conditions. Monte Carlo simulations are needed in order to evaluate the behavior of metallic high-Z collimators during operation scenarios using a realistic distribution of losses, which is a mix of the three limiting halo cases. Moreover, the consequences in the IR7 insertion of the worst (case) abnormal beam loss are evaluated. The case refers to a spontaneous trigger of the horizontal extraction kicker at top energy, when Phase II collimators are used. These studies are an important input for engineering design of the collimation Phase II system and for the evaluation of their effect on adjacent components. The goal is to build collimators that can survive the expected conditions during LHC stable physics runs, in order to avoid quenches of the SC magnets and to protect other LHC equipments.
WEPP071	Preliminary Exploratory Study of Different Phase II Collimators	2683
	L. Lari, R. W. Assmann, A. Bertarelli, C. Bracco, M. Brugger, F. Cerutti, A. Dallocchio, A. Ferrari, M. Mauri, S. Roesler, L. Sarchiapone, V. Vlachoudis CERN, Geneva J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz, J. C. Smith SLAC, Menlo Park, California L. Lari EPFL, Lausanne
	The LHC collimation system is installed and commissioned in different phases, following the natural evolution of the LHC performance. To improve cleaning efficiency towards the end of the low beta squeeze at 7TeV, and in stable physics conditions, it is foreseen to complement the 30 highly robust Phase I secondary collimators with low impedance Phase II collimators. At this stage, their design is not yet finalized. Possible options include metallic collimators, graphite jaws with a movable metallic foil, or collimators with metallic rotating jaws. As part of the evaluation of the different designs, the FLUKA Monte Carlo code is extensively used for calculating energy deposition and studying material damage and activation. This report outlines the simulation approach and defines the critical quantities involved.