GdfidL simulations
T. Bromwich
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Friday, 27 January 2017
1
Model of BPM cavity with beam pipe and waveguide slots
#-----------------—----—
# define materials
define(Aluminium, 1)
define(AluminiumKappa, 3.69e7)
#-----------------—----—
# parameters of the cavity
define(b1, 60.9e-3)
define(b2, 48.6e-3)
define(L, 5.8e-3)
define(Rc, 4e-3)
# parameters of the beam pipe
define(a1, 12e-3)
define(a2, 6e-3)
define(Rp, 3e-3)
define(PipeL, 37.3e-3)
# parameters of the waveguide slots
define(cx1, 2.3e-3)
define(cx2, 14.45e-3)
define(cy1, 14.45e-3)
define(cy2, 1.5e-3)
define(yslotpos, 18.75e-3)
define(xslotpos, 15.25e-3)
define(Lslot, 1.5e-3)
define(Rslot, 0.75e-3)
define(MeshStep, 0.2e-3)
define(MeshRangeX, (dy1/2) +ywgpos)
define(MeshRangeY, (dx2/2) +xwgpos)
#-----------------—----—
-general
outfile=
/scratch0/tbromwic/ATF_cavity
scratchbase= /scratch0/tbromwic/scratch#-----------------—----—
-material
material= Aluminium
type= electric
kappa= AluminiumKappa
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Friday, 27 January 2017
#-----------------—----—
-mesh
spacing= MeshStep
pxlow= -1*MeshRangeX, pxhigh= 1*MeshRangeX
pylow= -1*MeshRangeY, pyhigh= 1*MeshRangeY
pzlow= -L/2-PipeL, pzhigh= 1*(L/2+PipeL)
cxlow= ele, cxhigh= ele
cylow= ele, cyhigh= ele
czlow= ele, czhigh= ele
perfectmesh= no
#-----------------—----—
# fill the 'universe' with metal
-brick
material= Aluminium
xlow= -INF, xhigh= INF
ylow= -INF, yhigh= INF
zlow= -INF, zhigh= INF
doit
#-----------------—----—
# cavity - cut out the cavity as vacuum i.e. material 0
-ggcylinder
material = 0
range = (-L/2, L/2)
point = ( -b1/2, b2/2 -Rc )
arc, radius = Rc, type = clockwise
point = ( -b1/2 +Rc, b2/2 )
point = ( b1/2 -Rc, b2/2 )
arc, radius = Rc, type = clockwise
point = ( b1/2, b2/2 -Rc )
point = ( b1/2, -b2/2 +Rc )
arc, radius = Rc, type = clockwise
point = ( b1/2 -Rc,-b2/2 )
point = ( -b1/2 +Rc,-b2/2 )
arc, radius = Rc, type = clockwise
point = ( -b1/2, -b2/2 +Rc)
doit
….
2
Eigenvalue solver
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Friday, 27 January 2017
3
Simple cavity to look at effect of additional gap on frequency
Basic cavity
6.6418 GHz
Introduce 1mm deep gap
1mm wide (in z)
0.5mm wide (in z)
0.1 mm wide (in z)
Basic cavity geometry.
6.6013 GHz
6.6323 GHz
6.6407 GHz
Example of 1mm deep, 1 mm wide gap
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Friday, 27 January 2017
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Model of the Y waveguides and interior of feedthrough
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Friday, 27 January 2017
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Next steps
•  Model the complete BPM (started) •  Calculate the loaded Q and S-­‐parameters •  See how these values change by altering the posi?on of the feedthrough within the waveguide FONT
Friday, 27 January 2017
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