|Message: Electron multiplication in Electric field : maximum acceptable step||Not Logged In (login)|
Click on the Forum title, e.g. on the "Forums by Category" page, to read a sequence of postings to the Forum and its threads all in one page. If you are only interested in one thread or the thread following a specific posting, click the thread or the posting, which takes you to a smaller page, which contains only the part you are interested in and may be easier to navigate.
Messages are "chained" if there are only replies at the first level, i.e. 1/1.html, 1/1/1.html etc. In case of "chained" messages the message number is replaced by the icon and there is no indentation.
Inline: Display the subject line only or also the text of the posting(s); for the choice "All" the "Outline" choices are switched off.
|1||0||1||no text / full text of posting|
|2||1||All||text for level 1 only / text for All postings|
Outline: Choose the depth of the posting thread, successive toggle controls provide increasing detail.
|1||2||1||2 levels / 1 level (original posting)|
|2||3||2||3 levels / 2 levels|
|3||3||All||3 levels / all levels (all postings)|
I am testing electron multiplication with applied electric fields.
My simulation set-up is the following :
- An applied electric field (80 MV/km) in a air density of 3.059E-04 g/cm3. - Box size is very large - Initial 1 MeV electrons - using the "UserSteppingAction" I check what is the number of electrons with energy >= 1 MeV at given times of the simulation (1 us, 2 us, ..., 9 us) - After hundreds of initial particles shot, I get a multiplication factor, that is the number of electron >= 1 MeV at 6 us divided by the number of electrons shot initially.
I think one of the key points is how the trajectory of the particles are integrated (as they gain energy from the electric field).
I tried to play on three parameters : the range cut and the energy threshold (=production cuts), and the maximum acceptable step of the integrator.
My problem is the following :
when this maximum acceptable step is too low, then the multiplication factor decreases, and goes to ~0 for a step of < 10^-4 meters. I would expect this multiplication to stay constant (i.e. to converge) when the chosen maximum acceptable step reaches a given value that is small enough to integrate the field accurately. But this is clearly not the case here. See the attached figure.
What is the problem ?
Thanks in advance, -David
|Inline Depth:||Outline Depth:||Add message:|