NEG cartridges to create pressure bumps for MD

NEG cartridges to create pressure bumps for MD Christina Yin Vallgren, Giuseppe Bregliozzi on behalf of TE-VSC Helmut Burkhardt, Reyes Alemany Fernandez, Mika Huhtinen LSWG 2016 -03 -15 Vacuum, Surfaces & Coatings Group Technology Department 14 September 2021 Christina Yin Vallgren 2

Aim of the MD (MD 1224) • Understand sources of background in the experiments and their correlation with pressure readings. • => Create controlled local pressure bumps to localize the background to the experiments Vacuum, Surfaces & Coatings Group Technology Department 14 September 2021 Christina Yin Vallgren 3

NEG cartridge 1. 2. Modules used to accommodate the NEG cartridge Pumping capacities of the NEG Vacuum, Surfaces & Coatings Group Technology Department 14 September 2021 Christina Yin Vallgren 4

Module used at ATLAS IP to accommodate NEG cartridge 2. Ion pump 75 l/s 3. VGI: Ionization gauge 4. VGPB: Penning gauge 5. VGRB: Pirani gauge (>10 -4 mbar) 6. NEG cartridge: Capaci. Torr 400 Zr-V-Fe: SH 2 = 400 l/s SN 2 = 100 l/s SCO = 180 l/s Vacuum, Surfaces & Coatings Group Technology Department 14 September 2021 Christina Yin Vallgren 5

Module used at Sector Valve to accommodate NEG cartridge 8. VGI: Ionization gauge 5. VGRB: Pirani gauge (>10 -4 mbar) 9. NEG cartridge: Capaci. Torr 400 Zr-V-Fe: SH 2 = 400 l/s SN 2 = 100 l/s SCO = 180 l/s Vacuum, Surfaces & Coatings Group Technology Department 14 September 2021 Christina Yin Vallgren 6

NEG cartridge layout Vacuum, Surfaces & Coatings Group Technology Department 14 September 2021 Christina Yin Vallgren 7

LSS 1 (similar in LSS 5): Q 4 –Q 4 (range: -151 m – 151 m) -151 m -59 m-58 m -149 m -22 m -19 m Q 4 L 1 19 m 22 m 57. 9 m 58. 5 m 147 m 148 m 151 m Q 4 R 1 Vacuum, Surfaces & Coatings Group Technology Department 14 September 2021 author(s) 8

A 5 R 2. B static 1, 00 E-07 A 5 R 2. R static 1, 00 E-08 Injection H 2 by NEG 1. 2 e-8 mbar Measure Red Static 1, 00 E-09 1, 00 E-10 1, 00 E-11 1, 00 E-08 1, 00 E-12 1, 00 E-13 0 5 10 Lenght of Sector [m] 15 Pressure [mbar] A typical pressure bump during activation of NEG cartridge NEG Vacuum Pilot Sector 1, 00 E-09 1, 00 E-10 1, 00 E-11 1, 00 E-12 0, 00 50, 00 100, 00 150, 00 200, 00 Time [min] Vacuum, Surfaces & Coatings Group Technology Department 14 September 2021 author(s) 9

∆P as a function of Current/T Testing one of the NEG cartridges at 150 m from IP 5. Will validate the other NEG cartridges as well. P vs Current Q 4 L 5 1, 00 E-05 P vs Current - Q 4 L 5. R 1, 00 E-06 ∆Pressure [mbar] Max 30 -45 min P vs Current - Q 4 L 5. B 1, 00 E-07 1, 00 E-08 1, 00 E-09 1, 00 E-10 1, 00 E-11 1, 00 E-12 0 1 2 3 Current [A] 4 5 Vacuum, Surfaces & Coatings Group Technology Department 14 September 2021 Christina Yin Vallgren 10

Requests from ATLAS • Depending on the set current on the NEG cartridge, the pressure bump can be between 10 -8 mbar and 10 -6 mbar • Standard Interlock level in the LHC: 2 x 10 -6 mbar. => No need to mask the interlock during the injection. Pressure bumps of Position from IP Duration Comment from VSC H 2 22 m 10 min – 1 h ok H 2 58 m 10 min – 1 h ok H 2 150 m 10 min – 1 h ok H 2 270 m Not possible H 2 A 6 R 5 close to TCL ~218 m NEG cartridge installed in the TCL Vacuum, Surfaces & Coatings Group Technology Department 14 September 2021 author(s) 11