ECR (SPS Flange Impedance Reduction) Follow up for IWG C. Vollinger 16/08/2016

SPS Flange Impedance Reduction Flanges of the SPS with/without adjacent bellows shape cavities in the vacuum interconnects; These flanges are identified as one large source of impedance in the machine; Program of impedance reduction foresees the installation of flange shields and different designs were evaluated in the past. The so-called “double-tube” shield appears to give the best improvement in impedance reduction by reducing the R/Q by a factor of about 20 (with gap-filler included). 16/08/2016Christine Vollinger for IWG2

16/08/2016Christine Vollinger for IWG3

Steps taken after last IWG (#2 meeting) 16/08/2016Christine Vollinger for IWG4 1.Instead of rejecting the ECR, a delay of approval by 2 weeks to give room for further clarification was asked. 2. The decision on whether short-circuited flanges can be deployed everywhere cannot be made yet, so for the present the existing insulation scheme will be replicated. This decision needs to be taken before end 2016.

Strategy agreed with LIU-SPS and VSC 16/08/2016Christine Vollinger for IWG5 1.The agreed strategy for the EYETS is to produce the ~16 shields with the new design proposed in the ECR, while in parallel the impedance validation is made. A ‘yes/no’ answer will come from the impedance team ~2 weeks after the prototype shield is made available to them. If the answer is ‘no’, then the installation will be postponed. 2.As the only reason to go for this fall-back solution was the impossibility of getting production drawings ready in time for EYETS deployment, the final version for the YETS and LS2 can still be based on the more robust design initially proposed and validated as acceptable from impedance. Design work for this should therefore continue.

Tasks and Further Action Required 16/08/2016Christine Vollinger for IWG6 The impedance evaluation of the shield design presented in the ECR still needs to be made by simulation and measurement. RF do not anticipate problems, as it looks very similar to the PPS design in terms of impedance, but need to check that the addition of the insulated gap does not cause any unexpected effects. RF will launch the simulation as soon as the CATIA model is confirmed by VSC. (model available as of 16/08/2016) RF also need to make the measurements on a prototype or first production piece – VSC says this will probably not be available until end October, but will provide a date for the availability.