BE-ABP-HSC
Non convex chamber inPyECLOUD
Electron Cloud meeting 27-05-15
G. Iadarola, A. Romano, G. Rumolo
BE-ABP-HSC
Electron Cloud meeting 27-05-15
Electron Cloud meeting 27-05-15
PS standard Chamber
LHC standard Chamber
SPS Drift A Chamber
R = 78
mm
BE-ABP-HSC
Electron Cloud meeting 27-05-15
Electron Cloud meeting 27-05-15
PS standard Chamber
LHC standard Chamber
SPS Drift A Chamber
R = 78
mm
Non convex Polygon
BE-ABP-HSC
Electron Cloud meeting 27-05-15
Electron Cloud meeting 27-05-15
The chamber module in PyECLOUD The function “IsOutside”
checks if a point (x,y) is internal or external to the chamber. P lies outside the polygon if for at least one edge is verified:
The function “ImpactPointAndNormal”, computes the crossing point between the segment Pin Pout and the chamber’s profile
These algorithms work for convex polygon !
BE-ABP-HSC Electron Cloud meeting 27-05-15
The “IsOutside” function 1/3
Convex Chamber Non-Convex Chamber
BE-ABP-HSC Electron Cloud meeting 27-05-15
The “IsOutside” function 2/3Point-In-Polygon algorithm One simple way of finding if
a test-point is inside or outside a general polygon
The number of intersections for a ray, starting from the point and going in any fixed direction, says where is the point :
o If it is ODD, the point lies inside
o If it is EVEN, the point lies outside
BE-ABP-HSC Electron Cloud meeting 27-05-15
The “IsOutside” function 3/3
Convex Chamber No-Convex Chamber
BE-ABP-HSC Electron Cloud meeting 27-05-15
The “ImpactPointAndNormal” function 1/3
Convex Chamber No-Convex Chamber
BE-ABP-HSC Electron Cloud meeting 27-05-15
The “ImpactPointAndNormal” function 2/3 If the polygon is not convex,
we can have more crossing point between the segment Pin Pout and the chamber’s profile
The minimum value of the crossing point for a same segment shoud be taken
Pout
Pin
BE-ABP-HSC Electron Cloud meeting 27-05-15
Convex Chamber No-Convex Chamber
The “ImpactPointAndNormal” function 3/3
BE-ABP-HSC Electron Cloud meeting 27-05-15
Convex/nonconvex switch
convex polygon
The specific algorithm can be applied !
if the sign of all the cross
products is the same
For each set of three adjacent
point A,B,C find the cross
product AB x BC
Algorithm to detect the type of polygon
BE-ABP-HSC Electron Cloud meeting 27-05-15
Convex/noconvex switch
no-convex polygon
Algorithm to detect the type of polygon
For each set of three adjacent
point A,B,C find the cross
product AB x BC
if the sign of all the cross
products is the same
13
Electric Field X
Electric Field Y
PyPIC 1.02 : R
efined interpolation
BE-ABP-HSC Electron Cloud meeting 27-05-15
Electric Field X
Electric Field Y
PyPI
C 1
.01:
Ext
rapo
latio
n m
etho
d
Document reference 14
Model of the LHC beam screen
The aim is to study the EC build up through the holes of the
LHC beam screen with and without baffle plates BE-ABP-HSC Electron Cloud meeting 27-
05-15
Document reference 15BE-ABP-HSC Electron Cloud meeting 27-05-15
Document reference 16
Conclusion and Next Steps Implementation in PyECLOUD of non-convex
chamber geometries
Improvement of the code in order to correctly manage :
o detection of in/out particles with respect to the chamber
o impact of particles against the chamber wallo Interpolation of the electric field near the boundaries
Simulations on EC build up will be carried out in order to quantify the EC threshold and the Heat Load with and without baffle platesBE-ABP-HSC Electron Cloud meeting 27-
05-15
BE-ABP-HSC
Thanks for your attention!
Electron Cloud meeting 27-05-15
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