Summary of HV tests Operation meeting 28.07.2017 K.Fusshoeller, - PowerPoint PPT Presentation

Summary of HV tests Operation meeting 28.07.2017 K.Fusshoeller, L.Molina Bueno, P.Cotte 1

Schematics of detector and nominal HV configuration 2

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Temperature sensors Used those 5

Pressure sensors Pressure sensors Diff Pressure tank-insolation Diff Pressure tank - atm Absolute Pressure in tank 6

Summary of previous test results (28-06 → 05-07) ● Grid is the most sensitive part of the HV system, always trips first ● Liquid level above grid and maximum grid voltage (before trip) seem correlated (the more liquid above, the higher the voltage) ● Short time variation of liquid level does not seem to be correlated to max voltage ● Grid trip can provoke LEM trip, with or without delay – Which LEMs trip depends on which grid connection is used 7

Heinzinger ground connection problem (07.07 and 17.07) 8

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cathode_2017_07_17 Cathode falls to 0 by itself Unknown phenomenon 10

Was a cable problem. Has been fixed. 11

T otal number of trips per LEMs since last meeting CRP3 CRP2 LEM Up 4 trips 4 trips 4 trips 4 trips 5 trips 4 trips 13 8 trips 12 trips 20 trips 10 trips LEM Down trips 12 trips N S CRP5 CRP1 5 trips 8 trips 4 trips 7 trips 4 trips 4 trips 13 19 trips 12 trips 23 trips 10 trips 7 trips trips CRP8 CRP7 CRP6

Main results of the new tests: (details of all the tests at the end of the presentation) 13

1 st test: 14h between 17 th and 18 th Overview of grid, LEMs, liquid level, temperature and pressure during the test 14

Grid 15 Trip

LEMs down Grid trip induces Current on LEMs But no trip 16

LEMs up 17

Level meters 18

Temperatures gas liquid 19

Pressures 20

2 nd and 3 rd tests: -Grid reached 5.5kV -Grid held 5kV for 8 hours Overview of grid and LEM 21

Trips while going to 5.6kV 22

LEMs up manually put to 0 after trip LEMs down tripped with grid except 2, 5 and 12 23

Grid stable for ~8h at 5kV, then trips 24

LEM 9 tripped ~2h after grid on up side And on down side 25

Question: is the max voltage on the grid dependent on the voltage on the cathode? 26

So it seems... Maximum reached on Grid (kV) Cathode voltage (kV) 27

Other question: is the max voltage on the grid dependent the ramping speed? 28

Does not seem so... 29

Other question: is there a link between the variations of pressure and liquid level and the run stability? 30

14→15.07.2017 12→13.07.2017 = trip 26→27.07.2017 25.07.2017 particularly stable and yet trips No obvious correlation, but study needs refining 31

14→15.07.2017 12→13.07.2017 26→27.07.2017 25.07.2017 particularly stable and yet trips Again, no obvious correlation 32

For information : Cathode stability (example of test with grid at 5kV for 8h (26-27/07) 33

Cathode voltage and current 34

RMS of Cathode voltage RMS of Cathode current 35

Conclusion ● Possible link between max grid voltage and Cathode voltage: drift field lines will be modelised with Comsol to understand ● Trying higher Cathode voltages ● Need finer study to conclude on correlation between variation of liquid or pressure and HV stability 36

Thank you for your attention 37

Details of the runs 38