Current impedance issues

Impedance issues Short term issues: Isolated requests for impedance calculations of elements before hardware modification or installation Medium term issues Implementation and population of the impedance database (ZBASE) for PSB, PS, SPS and LHC. Long term issues Improving our methods to compute, simulate and measure impedances General questions

Long term : Understanding and improving our methods General questions: Impedance of structures with particles at low energy (PSB, PS) Formula for impedance of elliptic chamber Formula for impedance of elements with finite length Impact of external circuits of kickers Non linearity of the wake with transverse offset Properties of materials at very high frequencies? Measurement methods? Reliability of wire measurements Anomalous skin effect for CLIC (and maybe LHC at low temperature) Vanishing longitudinal impedance at low frequency (“hidden bypass”) Other ways to measure, compute, simulate impedance on bench or with beam?

Medium term : implementation of ZBASE Implementation of the Java based ZBASE Improvement of the Matlab based ZBASE (at the moment more than 5000 lines…) Allow possibility to import efficiently from different impedance calculation codes ABCI/ReWall/CST, for different machines and for varying beam parameters. Use the new model of kickers for the SPS impedance model

Short term : Impedance of single elements (1/2) LHC: plan of new vacuum chamber in ATLAS, request from Mark Gallilee/Ray Veness on December 2010(reduction of pipe aperture, new unshielded bellow, transition)  M4 Holes in DS collimator design request by Marc Timmins on February 2011  MKI request by (Mike Barnes) and MKD collimators with BPMs PIMS+ unshielded bellows RF cavities Rotatable Collimators beam screen weld beam screen holes TDI Septa Trapped modes in collimators

Short term : Impedance of single elements (2/2) SPS: Improve impedance model (request from SPS Upgrade study team) Pumping ports MSE, MST and ZS Shielded MKE kickers (request from Mike Barnes) Segmented MKPs Multilayer kicker (MKDH) PS Extraction kicker (request by Sandra Aumon on February 2011) Build the impedance model PSB Kickers with external circuit Y piece and ceramic chamber (request from M. Barnes and W. Wetterings)

Purpose of these informal meetings Discuss new results, problems and questions Gather and keep an eye on impedance requests Set priorities and needs for the team to be discussed with direct supervisors In brief…. Nothing changes…