10.106 SPEEDBUMP—Simulates a semi-circular protuberance from one or both walls of the chamber.

Simulates a semi-circular protuberance from one or both walls of the chamber.
Parallel capable? : yes
GPU capable? : no
Back-tracking capable? : no

Parameter Name UnitsType Default


L M double 0.0

insertion length

CHORD M double 0.0

z length of speed bump

DZCENTER M double 0.0

z center displacement of speed bump relative to middle of object

HEIGHT M double 0.0

height above the surrounding chamber

POSITION M double 0.0

position of peak relative to ideal trajectory

DX M double 0.0

horizontal misalignment

DY M double 0.0

vertical misalignment


direction from which inserted (x, +x, -x, y, +y, -y)


Historically, the interpretation of the POSITION parameter was dependent on the insertion direction. Set this to 1 to make it consistent with the SCRAPER element.


Optionally used to assign an element to a group, with a user-defined name. Group names will appear in the parameter output file in the column ElementGroup

This element simulates a commonplace type of aperture restriction, consisting of a bump on one or both sides of a chamber. The parameters of the speedbump are illustrated in Fig. 4 It may be useful to know that the radius R of the cylinder from which the speedbump is made is

    C2 + 4h2
R = ---------,

where C is the chord length and h is the bump height. Solving for h, we have

        ∘ -----(---)--
           2     C- 2
h = R -   R  -   2   .


Figure 4: Illustration of the parameters used in specifying a speedbump.