hom loss calculation of ip chambe r
DESCRIPTION
HOM loss calculation of IP chambe r. Nakano Hiroshi 7-Jul-2009 (presented by Hitoshi Yamamoto) Thanks to Tetsuo Abe and other experts. Beam parameters. Nano beam option s z (mm) = 6(LER)/6(HER) n- = 3.89x10 10 n+ = 6.78x10 10 #bunch = 3425(LER,HER). HOM calculation. - PowerPoint PPT PresentationTRANSCRIPT
HOM loss calculationof IP chamber
Nakano Hiroshi
7-Jul-2009(presented by Hitoshi Yamamoto)
Thanks to Tetsuo Abe and other experts
Beam parameters
Nano beam option•z (mm) = 6(LER)/6(HER)• n- = 3.89x1010
• n+ = 6.78x1010
• #bunch = 3425(LER,HER)
HOM calculation
GdfidL: 3D field calculation tool
Options•Two modes
•Grid moves with bunch (window wake = yes)•Grid fixed to lab (window wake = no)
•Symmtries•1/2,1/4 etc.
•Mesh sizes
Beam pipe data
60mrad(3.438deg)
15mm
10mm
HERLER
Bended to use ports
(pipes continue infinitely)
Calculation method
Window wake=yesMesh size 0.5 mm1/1 model
Window wake=no
Mesh size 0.3mm
Mesh size 1mm
1/2 model
Compare 6 ways of results
~400mm
~30mm
Are mesh sizes good?
Is it long enough?
Calculated in various crossing angles
port
*Window wake=Yes: use bunch-fixed grid
=No: use pipe-fixed grid
Results of HER
big small
big smallLoss factor
Crossing angle
60mrad
0.0004 V/pC ( )5.3 [W]
6 ways agreed with each otherwithin 10~20%
Consideration
If the change from “A” to “B” was slow, the loss factor might be small.
A B
EM will not stayBA
At small angles, the change isquasi-static; penetration of fieldto the side chamber is ~zero.
Results with 0.2 mm mesh GdfidL seems to work correctly.
HOM losses from and beams were calculated with 0.2 mm mesh size to get more ‘accurate’ values.
HER (r = 15mm)
LER (r = 10mm)
0.000551 V/pC (7.3W)
0.00145 V/pC (58W)
65W
HER
HER
LER
LER
New geometries
Type-1
Type-2
color: center of pipe
dashed: beam trajectory
IP
IP
All pipes have 10mm radius.Crossing angle of the beams is 60mrad.
before
IP
HER
LER
r = 15mm
r = 10mm
a
b
100 480 7.0
100 580 7.0
100 680 7.0
150 480 5.5
150 580 5.5
150 680 5.5
c
a b c loss factor
0.68
0.66
0.77
0.82
0.90
0.82
*mesh size = 0.2mm, 1/2 model
Type-1
Loss factor -> 1.2 * 10^-3[V/pC] ( in case of mesh size = 0.08mm)
36~48W (HER+LER)
64W
Check with finer mesh
HER
LER
Type-2
a’
b’
c 86 480 7.3
165 480 5.0 84 680 7.5165 680 5.0
a’ b’ c loss factor
1.9 / 2.3
2.4 / 2.1
1.8 / 2.4
2.1 / 2.2
*mesh size = 0.13mm, 1/2 model
HER / LER
115~119W (HER+LER)
Loss factor -> 2.1 / 2.4 * 10^-3[V/pC] ( in case of mesh size = 0.08mm)
124W
Check with finer mesh
HER
LER
Summary
• GdfidL gives stable(reliable) results– Within 10~20%– For different calculation modes, use of symmetries,
length of wake calculation, mesh size, etc.
• Crossing beam pipe designs for nano beam option have been evaluated for HOM- HOM loss is of order 50W~100W- Larger for larger crossing angles