take worst case
DESCRIPTION
Take worst case. MKI.D5R8.B2:TEMP_MAGNET_DOWN. 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 - PowerPoint PPT PresentationTRANSCRIPT
Take worst case
MKI.D5R8.B2:TEMP_MAGNET_DOWN
0
10
20
30
40
50
60
70
08/0
3/20
11 0
0:00
22/0
3/20
11 0
0:00
05/0
4/20
11 0
0:00
19/0
4/20
11 0
0:00
03/0
5/20
11 0
0:00
17/0
5/20
11 0
0:00
31/0
5/20
11 0
0:00
14/0
6/20
11 0
0:00
28/0
6/20
11 0
0:00
12/0
7/20
11 0
0:00
26/0
7/20
11 0
0:00
09/0
8/20
11 0
0:00
23/0
8/20
11 0
0:00
06/0
9/20
11 0
0:00
20/0
9/20
11 0
0:00
04/1
0/20
11 0
0:00
18/1
0/20
11 0
0:00
01/1
1/20
11 0
0:00
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
as measure of power in• Used cooling after beam off for measure of power
out
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
(de
g/h)
Heating rate
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
• Used 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
Outlook for 2012
315
320
325
330
335
340
345
350
0.00 5.00 10.00 15.00 20.00 25.00
Tem
p [K
]
Time [h]
50 ns spacing
1.0e11
2.0e11
1.5e11
315
320
325
330
335
340
345
350
0.00 5.00 10.00 15.00 20.00 25.00
Tem
p [K
]
Time [h]
25 ns spacing
0.8e11
1.4e11
1.1e11
2600 bunches
Longer-term behaviour• Saturation of temperature after a few fills
– Assumed 15 h coast, 4h turnaround (to 3.5 TeV)
0.00E+00
1.00E+14
2.00E+14
3.00E+14
4.00E+14
5.00E+14
6.00E+14
7.00E+14
8.00E+14
9.00E+14
1.00E+15
315
320
325
330
335
340
345
350
0 12 24 36 48 60 72 84 96 108 120 132 144 156 168
Inte
nsit
y [p
+]
Tem
p [K
]
Time [h]
50 ns, 1.6e11 per bunch
0.00E+00
1.00E+14
2.00E+14
3.00E+14
4.00E+14
5.00E+14
6.00E+14
7.00E+14
8.00E+14
9.00E+14
1.00E+15
330
332
334
336
338
340
342
344
346
348
70 71 72 73 74 75 76 77 78 79 80
Inte
nsit
y [p
+]
Tem
p [K
]
Time [h]
Temperature at injection• Cooling at about 3 deg per hour
– Cool to ‘interlock’ level after less than 1 h after dump– Cool to 334 K (61 C) after 2 h
50 ns, 1.6e11 per bunch
0.00E+00
1.00E+14
2.00E+14
3.00E+14
4.00E+14
5.00E+14
6.00E+14
7.00E+14
8.00E+14
9.00E+14
1.00E+15
330
332
334
336
338
340
342
344
346
348
70 71 72 73 74 75 76 77 78 79 80
Inte
nsit
y [p
+]
Tem
p [K
]
Time [h]
Temperature at injection• With 2e11 in 50 ns might be in trouble
– 2 h to cool to interlock limit– 4 h to reach 334 K (61 C)
50 ns, 2.0e11 per bunch
0.00E+00
1.00E+14
2.00E+14
3.00E+14
4.00E+14
5.00E+14
6.00E+14
7.00E+14
8.00E+14
9.00E+14
1.00E+15
330
332
334
336
338
340
342
344
346
348
70 71 72 73 74 75 76 77 78 79 80
Inte
nsit
y [p
+]
Tem
p [K
]
Time [h]
Looks better for 25 ns• Cooling at about 3 deg per hour
– Cool to ‘interlock’ level after less than 1 h after dump– Cool to 334 K (61 C) after 2 h
50 ns, 1.6e11 per bunch
Conclusions• Worse for 2012 if push 50 ns intensity
– Might affect operation at 2e11 per bunch
• 25 ns seems to have more margin – looks OK for 1.1e11 per bunch and 2600 b