How to make protons ionize on helium gas: CST studio...

[lgee]

Hi all,

Really struggling here: trying to get a proton beam to ionise with a helium gas volume in CST Studio. I am currently using the PIC solver and I can get an electron beam to interact with a solid but not a gas, but I can't get a proton beam to interact with anything. I keep getting the following errors and warnings:

W: PIC simulation time is smaller than the source excitation time.
W: No hardware device detected, solver is started without Hardware Accelerator Device.
Electrostatic Solver
Iteration Step: Residual:
1 1.055509e-01
10 1.421296e-03
20 3.059682e-06
Final (22) 7.988341e-07

Electrostatic Solver successful
W: The 3D time monitor space charge (t=0.5..end(0.0)) is defined outside the estimated simulation time and will be ignored.
Ionization is enabled for the full background volume.
The properties of the material 'Fluid/Helium (20C 1atm) (CHT)' are used.
Ionization threshold energy: 0.000000 eV
E: vector<T> too long
E: Time Domain Solver (HEX) terminated abnormally.

I can probably post a link to the CST file if this is of use? Just let me know. I also don't know the correct place for this so let me know if this is wrong too..

Cheers

 

[dick_freebird]

Protons have a low probability of interacting with gaseous material.

There will be a dE/dx that depends on material density. You may find semi-related data in papers relating to semiconductor single event effects (but here I see a wide range of LET reported in various references).

Perhaps the density of helium falls below the resolution limit? Or perhaps at low densities the interaction is more statistical / stochastic than deterministic?

 

[lgee]

Here is a link to my cst file: [Moderator action: removed link to external file server]

I have tried making the gas like 1000atmospheres pressure but that seems to do nothing either...

Here is the ionization cross section file I used also:

0 0
28e+13 0.04370e-20
30.60e+13 0.07700e-20
33.60e+13 0.11320e-20
38.60e+13 0.16580e-20
45e+13 0.21950e-20
52e+13 0.26350e-20
67e+13 0.32230e-20
90e+13 0.36050e-20
118e+13 0.36990e-20
160e+13 0.35730e-20
275e+13 0.29840e-20
450e+13 0.23120e-20
870e+13 0.15060e-20
2650e+13 0.06420e-20
8000e+13 0.02540e-20
10000e+13 0

Do you have any secific information regarding the vector<T> too long error?

Thanks

 

[lgee]

Here try this: attached is cst file

I have tried making the gas like 1000atmospheres pressure but that seems to do nothing either...
Here is the ionization cross section file I used also:
0 0
28e+13 0.04370e-20
30.60e+13 0.07700e-20
33.60e+13 0.11320e-20
38.60e+13 0.16580e-20
45e+13 0.21950e-20
52e+13 0.26350e-20
67e+13 0.32230e-20
90e+13 0.36050e-20
118e+13 0.36990e-20
160e+13 0.35730e-20
275e+13 0.29840e-20
450e+13 0.23120e-20
870e+13 0.15060e-20
2650e+13 0.06420e-20
8000e+13 0.02540e-20
10000e+13 0
Do you have any secific information regarding the vector<T> too long error?
Thanks

 

[lgee]

Does bumping work on this forum? Does anyone have any ideas on this? Maybe even just a working example where a proton beam is interacting with a gas?

lgee

 

[BradtheRad]

Does bumping work on this forum? Does anyone have any ideas on this? Maybe even just a working example where a proton beam is interacting with a gas?

* Cloud chamber - detects charged particles (including protons) by revealing their condensation trails through a fine mist. From one standpoint it's tiny drops of liquid suspended in cold air, although from another standpoint it's a dense gas.

* Wilson cloud chamber - has liquid hydrogen near the temperature where it changes to a gas.

* Proton beam therapy is used to direct radiation at a cancerous tumor. Although flesh isn't a gas, the principle of operation might reveal concepts useful to get some kind of simulation working for you.