investigation of 0.1s bunch gap
DESCRIPTION
Investigation of 0.1s bunch gap. Earlier runs had shown large temperature losses in the hot zone after 0.1s, of the order of 60-80%. There was some uncertainty over these results because the time step between solutions was too large. - PowerPoint PPT PresentationTRANSCRIPT
1G.E. Ellwood
Advanced Materials Group 1
• Earlier runs had shown large temperature losses in the hot zone after 0.1s, of the order of 60-80%.
• There was some uncertainty over these results because the time step between solutions was too large.
• As the results are cumulative and depend on the result from the previous solution, the later results couldn’t be relied on even if they looked more even.
Investigation of 0.1s bunch gap
2G.E. Ellwood
Advanced Materials Group 2
Initial work
• I used a small model (x=.5mm, y=.05mm, z=.5mm). With a 10mx10mx100m mesh.
• I used symmetric boundary conditions to allow me to reduce the model to ¼ of its normal size.
• I took the input file supplied by Luis that gave the heat deposition from a 250GeV beam over a volume 1mm x .1mm x 30mm.
• This allowed me to study time steps to find out over what gap was needed to remove the uncertainty.
• I’ve taken the temperature of the hottest node and plotted it against time.
3G.E. Ellwood
Advanced Materials Group 3
0
50
100
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300
0.00E+00
2.00E-03 4.00E-03 6.00E-03 8.00E-03 1.00E-02 1.20E-02 1.40E-02 1.60E-02 1.80E-02 2.00E-02
Time (s)
Te
mp
era
ture
(°C
)0<t<0.02s 100 sub-steps
4G.E. Ellwood
Advanced Materials Group 4
0
50
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0.00E+00 5.00E-04 1.00E-03 1.50E-03 2.00E-03 2.50E-03 3.00E-03 3.50E-03 4.00E-03
Time (s)
Te
mp
era
ture
(°C
)0<t<.004s 40 sub-steps
5G.E. Ellwood
Advanced Materials Group 5
0
50
100
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0.00E+00
1.00E-04 2.00E-04 3.00E-04 4.00E-04 5.00E-04 6.00E-04 7.00E-04 8.00E-04 9.00E-04 1.00E-03
Time (s)
Te
mp
era
ture
(°C
)
0<t<.001s 40 sub-steps
6G.E. Ellwood
Advanced Materials Group 6
50
60
70
80
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100
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140
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0.00E+00
1.00E-04
2.00E-04
3.00E-04
4.00E-04
5.00E-04
6.00E-04
7.00E-04
8.00E-04
9.00E-04
1.00E-03
Time (s)
Te
mp
era
ture
(°C
)
0.02
0.004
0.001
Combined results 0<t<.001s
7G.E. Ellwood
Advanced Materials Group 7
50
60
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80
90
100
110
120
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140
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0.00E+00 5.00E-04 1.00E-03 1.50E-03 2.00E-03 2.50E-03 3.00E-03 3.50E-03 4.00E-03
Time (s)
Te
mp
era
ture
(°C
)
0.02
0.004
0.001
Combined results 0<t<.004s
8G.E. Ellwood
Advanced Materials Group 8
Initial findings
• The best results were found with a 2.5x10-5s time interval.
• Although when the time step is too large there is an uncertain region in the results, this doesn’t seem to affect the later results. – This is shown on slides 6 & 7.
• 0.1s is enough time for the temperature to spread outside the boundaries of the volume modelled here. – But in this model the heat isn’t allowed to
spread past the boundaries so the overall temperature may be higher than would be seen in reality.
9G.E. Ellwood
Advanced Materials Group 9
Later work
• I used a larger model (x=.5mm, y=.05mm, z=5mm). With a 10mx10mx100m mesh.
• I used symmetric boundary conditions. • I took the input file supplied by Luis used
previously. • I used a time gap of 2.5x10-5s, and studied the
0<t<.005s.– This was the region where most heat loss
occurred, and where there was uncertainty over the results.
10G.E. Ellwood
Advanced Materials Group 10
0
50
100
150
200
250
300
0.00E+00
5.00E-04
1.00E-03
1.50E-03
2.00E-03
2.50E-03
3.00E-03
3.50E-03
4.00E-03
4.50E-03
5.00E-03
Time (s)
Tem
pera
ture
(°C
)
11G.E. Ellwood
Advanced Materials Group 11
Conclusions
• With the limited time and space model used, I’ve found the hottest node has decreased from 253°C to 48°C after 0.005s.
• If a larger volume could be modelled at times up to 0.1s, a greater temperature loss would be seen but isn’t calculable from these results.