CERN Accelerating science

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New variables in Formula Editor

With MolFlow 2.3.5, two long-requested features have been added to the expressions that you can use in Formula Editor.

1) Mean Free Path / Mean Pumping Path

Adding the "MFP" or "MPP" variables will display the mean free/pumping path in centimeters, that is, the total length travelled by particles in the system divided by the number of hits / number of absorbed particles.




2) Sums for selection groups

MolFlow now fully supports defining part of the geometry as selection groups. In the formula editor, it is now possible to refer to a group of facets and perform sum operation on them. The syntax is the following:


where prefix can be:

  • AR (area of facets)
  • A (number of absorbed particles)
  • H (nimber of hits on the facets)
  • D (number of particles desorbed from the facets)


  • SUM(A,S3) will calculate the total number of particles absorbed on facets that are part of selection group 3
  • SUM(AR,S1) tells the total area of all facets in selection group 1

SynRad quick start tutorial

The best way to start using SynRad is to set up a simple sytem with two dipoles and interpret results. There is a 10-minute quick start guide to do just that:


You can also see how eactly the tutorial is solved on this Youtube video (set quality to 720p to see text):


SynRad released

SynRad is a new MC simulator for calculating flux and power distribution of synchroton radiation in geometries of arbitrary complexity. It has a similar interface to Molflow and both programs read each other's file formats. You can also export the flux distribution and use it as an outgassing map in Molflow.


Try it out in the downloads section.


Creating Outgassing maps

Recently two MolFlow users have been facing a similar problem:

One of them wanted to simulate outgassing due to beam loss, others had outgassing due to electrons in the system. In both cases, they had a distribution of outgassing that changed depending on the location. The only way to enter it to MolFlow was to create a matrix of facets, and define the outgassing rate one-by-one. A rather long and boring process.
So I decided to create a way of defining a spacial outgassing distribution. The key is the Explode command that existed already in Molflow.
First, you have to define how fine the outgassing matrix is by defining a regular mesh:
Then we select the facet and issue the new "create outgassing map" command:
Below you see a map of the facet. For each mesh element, you can manually set the outgassing value. Note that the edited cell's location is highlighted on the geometry (similar to texture plotter):
Click image to magnify)
You can also paste values from the clipboard from Excel. The values are pasted to the right and bottom from the actual cell. Then you can define the desorption type (Uniform, Cosine, Cosine^N). Finally, if everything's ready, click Explode.
The exploded geometry highlights those facets that have a desorption now:
To test that everything was well defined, add a mesh that counts desorbed molecules, and you'll see a nice colormap of the values you just entered:
That wasn't hard, was it? Happy outgassing! ;)

Facet selection groups

If you have carefully selected a group of facets, let's say all part of a given structure, then you probably won't want to select them once again.

That's why the Memorize selection function was added, allowing you to create facet groups, which are saved with the geometry file.

To use it, simply select some facets, then use Selection menu / memorize selection (shortcut: CTRL+W), and give your selection a name.




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