LINAC3 INSTRUMENTATION STATUS F.Roncarolo 19 Nov 2014
F.Roncarolo 19 Nov 20141
Slide 2
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
Slide 3
New Pepper Pot @ Linac3 Purchased from Pantechnik F.Roncarolo
19 Nov 20143 New diagnostics tank hosting Slit Pepper Pot FC Pepper
Pot
Slide 4
New Pepper Pot @ Linac3 F.Roncarolo 19 Nov 20144 Here in the
parking position BEAM Pepper pot plate MCP, PHOSPHOR Mirror
Camera
Slide 5
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 detector
@parking Aug 29 th : @ ~9p.m. abrupt change of LEBT vacuum (see
next slide) F.Roncarolo 19 Nov 20145
Slide 6
LEB vacuum Aug 29 th (A.Michet) F.Roncarolo 19 Nov 20146
Problem traced back to leak along pepper pot plate cooling
circuit
Slide 7
Cooling circuit F.Roncarolo 19 Nov 20147 Bellow clearly not
straight
Slide 8
Leak tests Pantechnik before delivery: leak rate < 1.10-9
mbars.l.s-1 TE-VSC (A.Michet) before installation (meas in the lab,
pressurized He): Leak rate 2.3 10-10 mbar.l/s at 4 bars and 3.7
10-10 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 20148 w/o dismounting cooling circuit
is difficult to identify exactly where the leak is
Slide 9
End of firsts episode, now the second F.Roncarolo 19 Nov
20149
Slide 10
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 : 40105106 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 34
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 201410
Slide 11
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 1.0 10-7 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 mbarl/s with a background
Slide 12
Pepper Pot Back to Pantechnick 2 eMail 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 201412
Slide 13
Pepper Pot Back to Pantechnick 2 eMail on Nov 17 th (this
Monday): Finally a leak occurred during the week end F.Roncarolo 19
Nov 201413 slow increaseSudden leak Leak detector fault (and was it
sturated at 10-8?)
Slide 14
Pepper Pot Back to Pantechnick 2 eMail 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
201414
Slide 15
SEM grids-Test with beam F. Zocca F.Roncarolo 19 Nov 201415 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
Slide 16
LINAC3 SEMGRID ITL.MSF03HV F.Roncarolo 19 Nov 201416 Vacuum
team inspection March 2014:
https://dfs.cern.ch/dfs//Departments/AB/Groups/BI/Sections/PM/Projects/LINAC3/ITL.MSF03HV_P
ICS_22Aug2014/Cote SEM grid avt nett.avi FRONT SIDEBACK SIDE Visual
Inspection Sep2014:
Slide 17
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 201417
Slide 18
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 201418
Slide 19
SPARE F.Roncarolo 19 Nov 201419
Slide 20
Leak Detection (A.Michet) F.Roncarolo 19 Nov 201420