Heating and Outgassing from MKP- L Magnet M.J. Barnes & L. Sermeus Acknowledgements: M. Beck, H. Bartosik, G. Bregliozzi, C. Pasquino, G. Rumolo, L. Vega Cid 20/04/2016MKP strategy meeting1

20/04/2016MKP strategy meeting2 MKP-L replaced during Christmas shutdown of Significant pressure and temperature rise observed during operation. Try to separate out pressure rise due to multipacting and temperature rise…. 24/04/15 13/06/15 02/08/15 21/09/15 10/11/1530/12/15 18/02/16 08/04/16 mbar 7E-7 6E-7 5E-7 4E-7 3E-7 2E-7 1E-7 0E Background to MKP-L

20/04/2016MKP strategy meeting3 25 ns Scrubbing Run of 19/06/15 to 20/06/15 To determine approximate relationship between pressure and measured temperature: Go through TIMBER data since mid-March 2015 and make a note of pressure when there is no fast vacuum activity. No fast vacuum activity

20/04/2016MKP strategy meeting4 Pressure vs. Meas. Temp. from 20/3/15 to 11/04/16 (1) Group into time intervals (2) Plot pressure on logarithmic scale  For a given measured temperature, there has been a reduction in pressure by a factor of 4-5 between Mar- Apr and Feb-Apr 2016 (4 at 30˚C; 4.5 at 45˚C).  Thus a measured temperature of 50˚C, without beam, would be expected to give a pressure of 2.3x10 -7 mbar during March 2015 and 5x10 -8 mbar during April 2016 Note: see Lorena’s talk for correlation between measured temperature and ferrite temperature.

20/04/2016MKP strategy meeting5 Pressure Corrected for Temp. 19/06/15 to 20/06/15 (25ns scrubbing run) (1) Use curve-fit from previous slide to correct pressure for temperature: During the cooldown from 60˚C measured, the green (corrected) trace goes slightly negative, indicating that operation at an elevated temperature may have helped to reduce outgassing. (2) Corrected pressure and maximum beam intensity: In general the two curves have the same shape, indicating that the fast rise, corrected, pressure is attributable to multipacting; Methods of reducing SEY are being considered (e.g. LESS and aC); The normalized pressure, corrected to 30˚C measured, is ~1x mbar/proton.

20/04/2016MKP strategy meeting6 Pressure Corrected for Temp. 25/03/16 to 28/03/16 (25ns scrubbing run) Has the normalized pressure rise reduced, i.e. conditioning, since June 2015? 1.3 x10 -7 mbar and 3.22 x10 13 protons  ~ 4x mbar/p (c.f. 1x mbar/p in June 2015). Hence some (limited) conditioning…. Does 50 ns beam result in fast outgassing? – data very difficult to find for 2015…. Combine a 50 ns MD with evaluating beam induced power deposition in MKE4 magnets?

20/04/2016MKP strategy meeting7 Conclusions and Questions  For a given measured temperature, there has been a reduction in pressure by a factor of 4-5 between Mar- Apr and Feb-Apr 2016 (4 at 30˚C & 4.5 at 45˚C).  Thus a measured temperature of 50˚C, without beam, would be expected to give a pressure of 2.3x10 -7 mbar during March 2015 and 5x10 -8 mbar during April  Operating at elevated temperature reduces subsequent outgassing.  Hence: is it necessary to implement means to reduce beam induced power deposition short- term?  Fast vacuum activity correlates well with maximum beam intensity  multipacting;  During June 2015 normalized pressure, corrected to 30˚C measured, was ~1x mbar/p.  During March 2016 normalized pressure, corrected to 30˚C measured, was ~4x mbar/p.  Important to confirm that the fast vacuum activity is multipacting: Giovanni Rumolo team to simulate 25ns and 50ns beam….  Combine a 50 ns MD with evaluating beam induced power deposition in MKE4 magnets?  Maybe coating ferrite of spare the MKP-L, e.g. with aC, should be considered as a high priority.

20/04/2016MKP strategy meeting8 Thank you for your attention