LINAC3 INSTRUMENTATION STATUS F.Roncarolo – 19 Nov 2014 F.Roncarolo 19 Nov 20141

Few slides from last LIU Ions Linac3 study group meeting (to be read by whom lost the first episode of the pepper pot saga) F.Roncarolo 19 Nov 20142

New Pepper Linac3 Purchased from Pantechnik F.Roncarolo 19 Nov New diagnostics tank hosting Slit Pepper Pot FC Pepper Pot

New Pepper Linac3 F.Roncarolo 19 Nov Here in the parking position BEAM Pepper pot plate MCP, PHOSPHOR Mirror Camera

Status New tank installed in July (equipped with slit and FC, no pepper pot detector) Pepper Pot detector installed Aug 22 nd Aug 28 th : Few tests with beam from 10 to 12 a.m., then Aug 29 th ~9p.m. abrupt change of LEBT vacuum (see next slide) F.Roncarolo 19 Nov 20145

LEB vacuum Aug 29 th (A.Michet) F.Roncarolo 19 Nov Problem traced back to leak along pepper pot plate cooling circuit

Cooling circuit F.Roncarolo 19 Nov Bellow clearly not straight

Leak tests Pantechnik before delivery: leak rate < mbars.l.s-1 TE-VSC (A.Michet) before installation (meas in the lab, pressurized He): Leak rate mbar.l/s at 4 bars and mbar.l/s at 5 bars TE-VSC (A.Michet) on Sep 1 st after LEBT vacuum deterioration Leak rate ~10-4 mbar.l.s-1 (meas in situ, pressurized He) TE-VSX (A.Michet) on Sep 8 th after detector removal from the tank Cooling circuit put under vacuum (~10e-8 ) Injection of He around cooling circuit bellow Pressure up to ~10e-6 mbar.l/s F.Roncarolo 19 Nov w/o dismounting cooling circuit is difficult to identify exactly where the leak is

End of firsts episode, now the second … F.Roncarolo 19 Nov 20149

Pepper Pot Back to Pantechnick 1 Report on Oct 10 th : The Pepperpot has been received in PANTECHNIK facility the 03rd of October 2014, a Vacuum test has been performed directly on the cooling system of the measure head. Tools used : ➢ a vacuum detector, Pfeiffer, HLT560, S/N : ➢ a He bottle equipped with manometer and a precised gun ➢ a Manual angle valve DN25 Iso-KF ➢ one Hose DN25 with seals and clips DN25 The pressure measured on the cooling system was 3.8*10-8 mbars.l.s-1, during injection of He the pressure decreased to 5*10-5 mbars.l.s-1 around the water connections Swagelok. The connections has been tightened by 3⁄4 round. Then the vacuum has been retested and the pressure measured was 4*10-10 mbars.l.s-1. Micro Injection of He has been performed on the water cooling circuit without incidence on the pressure measured. Finally to validate the repair, a Vacuum test has been performed on the entire system. The pressure measured was 8*10-10 mbars.l.s-1. Micro Injection of He has been performed on all the critical parts without incidence on the pressure measured. F.Roncarolo 19 Nov

Pepper Pot back to CERN Report on Oct 28 th by A.Michet The pepper-pot was under vacuum, the pressure inside the pump down system was mbar. A Leybold Oerlikon PhoeniXL 300 helium leak detector was connected to the pumping group. The cooling circuit was pressurized 5 times at 5 bars. The leak rate increased during each cycle (until 10-9 mbar∙l/s with a background <10-10 mbar∙l/s). The leak was not stable increasing during each test. Another 10 cycles of pressurization and pumping were done. The cooling circuit remained at 5 bars (static pressure) during night (see figure 1). The record (figure 1) shows that the leak rate was first decreasing and suddenly increased up to 1, mbar∙l/s (after 16 hours at 5 bars of static pressure). The pressure inside the pumpdown system increased up to 1, mbar CONCLUSION A leak of mbar∙l/s was found on the cooling circuit of the pepper-pot when pressurized to 5 bars. The repair done by the firm is not stable in time; the cooling circuit of the pepper- pot is still leaking and cannot be installed into Linac 3. F.Roncarolo 19 Nov

Pepper Pot Back to Pantechnick 2 on Nov 14 th ( last Friday): 1) At the receipt of the pepperpot we have proceed to a leak test from both side of the pepperpot (water circuit and pepperpot tank). The leak rate was < 1.10e-9 mbars.l.s 2) We have proceed to the cycling tests according to the procedure sent. 10 cycles was done without any leak (leak rate ~5.10e-10 mbars.l.s) 3)we tested the water circuit at 5 bars during 24h. 4) After the 24h we tested again at 5 bars during one night (~ 15h) 5) Today I started again a cycling tests, 14 cycles was done without problems. We will leave the pepperpot at 5 bars (water circuit side) during the week end and the leak rate will be recorded in a file. F.Roncarolo 19 Nov

Pepper Pot Back to Pantechnick 2 on Nov 17 th (this Monday): Finally a leak occurred during the week end F.Roncarolo 19 Nov slow increaseSudden leak Leak detector fault (and was it sturated at 10-8?)

Pepper Pot Back to Pantechnick 2 on Nov 19 th (today): Bonjour Federico, We started to investigate but unfortunately we had a problem with our leak detector. About the leak, it seems to be the bellows or the ceramic insulators (or the soldering), now we have to determine which one. We think that the fittings are ok. Today we will borrow a leak detector from our neighbor "Sominex". If everything going well, we should be able to find the leak very soon and plan a repair. We keep you informed. F.Roncarolo 19 Nov

SEM grids-Test with beam – F. Zocca F.Roncarolo 19 Nov SEM grid INSEM grid OUT Frame polarization ON (70 V)620 mV580 mV Frame polarization OFF (HV cable floating) 640 mV0 mV The pulse signal amplitude read by the Faraday Cup (FC) is recorded as a function of the SEM grid position (IN or OUT) and the grid frame polarization (ON or OFF) Conclusion: -when the SEM grid is IN, the frame polarization does not affect the downstream beam transmission  FC signal intensity unchanged with both polarization ON or OFF -when the SEM grid is OUT (parking position), the frame polarization has an effect on the beam transmission (kick?)  it looks like the beam transmission has been optimized when the frame polarization is ON and goes to zero when it is switched OFF. FC signal

LINAC3 SEMGRID ITL.MSF03HV F.Roncarolo 19 Nov Vacuum team inspection March 2014: ICS_22Aug2014/Cote SEM grid avt nett.avi FRONT SIDEBACK SIDE Visual Inspection Sep2014:

LINAC3 SEMGRID ITL.MSF03HV (from BI-TB Oct 2014) Grid is clearly sticking into the beam pipe aperture when in the parking position Frame and/or bias plates hit by ions and gets charged confirmed by beam-based (quick) tests can improve discharge (now done through HV power supply) Likely requires mechanical design change - BI-ML + BI-PM to decide longer shaft ? protecting (dischargeable) plate? Had no time yet - Decision pending What about other SEM grids? Need a fellow-student to characterize the situation? F.Roncarolo 19 Nov

LINAC3 FCs (from BI-TB Oct 2014) BE-ABP recognized hints of secondary electrons showers (from losses on beam pipe?) reaching the cup sensor  unexpected negative peaks Offer from Pantechnik for two cups equipped with additional ‘electrons shielding’ BI-ML: they do not fit into existing tanks BI-ML + BI-PM to decide for in-house design or outsource detectors fitting into tanks Had no time yet - Decision pending F.Roncarolo 19 Nov

SPARE F.Roncarolo 19 Nov

Leak Detection (A.Michet) F.Roncarolo 19 Nov