Large spread in measured D T (10 – 40 deg)
description
Transcript of Large spread in measured D T (10 – 40 deg)
Large spread in measured DT (10 – 40 deg)
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MKI.A5L2.B1:TEMP_MAGNET_DOWN MKI.A5L2.B1:TEMP_MAGNET_UPMKI.A5R8.B2:TEMP_MAGNET_DOWN MKI.A5R8.B2:TEMP_MAGNET_UPMKI.B5L2.B1:TEMP_MAGNET_DOWN MKI.B5L2.B1:TEMP_MAGNET_UPMKI.B5R8.B2:TEMP_MAGNET_DOWN MKI.B5R8.B2:TEMP_MAGNET_UPMKI.C5L2.B1:TEMP_MAGNET_DOWN MKI.C5L2.B1:TEMP_MAGNET_UPMKI.C5R8.B2:TEMP_MAGNET_DOWN MKI.C5R8.B2:TEMP_MAGNET_UPMKI.D5L2.B1:TEMP_MAGNET_DOWN MKI.D5L2.B1:TEMP_MAGNET_UPMKI.D5R8.B2:TEMP_MAGNET_DOWN MKI.D5R8.B2:TEMP_MAGNET_UP
Take worst case
MKI.D5R8.B2:TEMP_MAGNET_DOWN
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01/1
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T [C
]
Analysis of heating
• Took all fills (to end September) where in stable beams for longer than 10 h
• Considered only time from top of ramp onwards
• Used number of bunches, average bunch current and bunch length as inputs
• Fitted initial heating rate (~linear) over first 2 hours
Analysis (to end September)
0 10 20 30 40 50 60 70 800
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2x 10
14
Fill
p+
Total intensity
0 10 20 30 40 50 60 70 800
0.2
0.4
0.6
0.8
1
1.2
x 10-9
Fill
s
Bunch length
0 10 20 30 40 50 60 70 800
2
4
6
8
10
12
14x 10
10
Fill
Inte
nsity
p+
Bunch intensity
0 10 20 30 40 50 60 70 800
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Fill
Rat
e in
firs
t 2 h
(deg
/h)
Heating rate
Dependencies
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
x 1014
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1x 10
-14
Total intensity p+
Hea
ting
(deg
/h)
Heating * Lb2 * Nb vs total intensityquadratic
Can we model including cooling?• Semi-empirical model makes reasonable predictions
– Replicates cooling after about 12 h– Assuming heating from beam power ( Nb, Ib^2, 1/Lb^2),
cooling from radiation ( DT^4) and from conduction ( DT)
0.00E+00
2.00E+13
4.00E+13
6.00E+13
8.00E+13
1.00E+14
1.20E+14
1.40E+14
1.60E+14
1.80E+14
2.00E+14
324
326
328
330
332
334
336
21:36:00 00:00:00 02:24:00 04:48:00 07:12:00 09:36:00 12:00:00 14:24:00 16:48:00 19:12:00
MKI.D5R8.B2:TEMP_MAGNET_DOWN
fit
LHC.BCTFR.A6R4.B2:BEAM_INTENSITY
Cooling coefficients
• Use cooldowns at technical stops or MDs
295
300
305
310
315
320
325
330
12:00:00 0:00:00 12:00:00 0:00:00 12:00:00 0:00:00 12:00:00
To do...
• Fit all fills with same heating and cooling coefficients– Already started to extract cooling coefficients from
the cooling curve when beam switched off• Update with October data• Extrapolate to 2012 and beyond• Derive some ‘operational’ limitations
Concerns and possible upgrades• Reducing heating of MKIs
– Reduced bunch length/better bunch shaping– New shielding with more stripes
• Question – are temperature rises lower on kickers with more stripes?– Metalised chamber
• Improving vacuum in MKIs– NEG coating of 2nd chamber?– Solenoids around 2nd chamber?– New SIS or SS interlocking/procedures?
• UFOs in ceramic chambers with kicker pulsing– Coating? Cleaning?
• Clearly need to group any upgrades and have common study with all aspects considered