Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Please, Help. Problems with calculation of partical trajectories

Please login with a confirmed email address before reporting spam

Hello Everyone!
Maybe can Someone help me? I can't find out what I do wrong in Partical Tracing modul (AC/DC) for calculation of partical trajectories.
I have model with four electrodes. One from them is cathod. Three other are anodes or regulators of electric field in dependence from set value of potencials. Cathod generate electrones through field emission.
On first step I had calculated distribution of electric field in my structure using Electrostatics modul. There are not problems. On second step in Charged Particle Tracing modul (AC/DC) I had used "Electric force" and "Inlet" ("Wall" and "Partical properties" had left the default). In "Electric force" I had set data of calculated electric field on first step. In "Inlet" I had set "Release Time" and chosen "Density" in "Initial position". Then I had input "Number of particles" and "Density proportional". After that in Time dependent study I had input simulation time. Then calculation was started.
System gave me wrong results after making those actions: trajectories of particles are straight as though they weren't reacted at electric field. When I had decreased cell of mesh or desreased step of time in "Study", calculations is not converged.
I am new in COMSOL and I can do something wrong. Please, help me to find out why particles don't react at electric field. Maybe does someone know suitable samples?
Thanks in advance to anyone who can help me.

2 Replies Last Post 2016年5月17日 GMT-4 19:39
Christopher Boucher COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 2016年5月16日 GMT-4 09:59
Hi Mikalai,

If the particles are completely unaffected by the electric field, it is possible that the settings for the Time Dependent study need to be changed.

In the settings for the Time Dependent study step, in the Values of Dependent Variables section, make sure that the folllowing settings are used.

Under "Values of variables not solved for":
Settings -> User controlled
Method -> Solution
Study -> (This should be whichever study was used to compute the electric field).

If you have both the AC/DC Module and the Particle Tracing Module, the following examples are very instructive for coupling external fields to the particle trajectory calculation:
Quadrupole Mass Filter: www.comsol.com/model/quadrupole-mass-filter-12039
Quadrupole Mass Spectrometer: www.comsol.com/model/quadrupole-mass-spectrometer-10653

Best Regards,
Chris
Hi Mikalai, If the particles are completely unaffected by the electric field, it is possible that the settings for the Time Dependent study need to be changed. In the settings for the Time Dependent study step, in the Values of Dependent Variables section, make sure that the folllowing settings are used. Under "Values of variables not solved for": Settings -> User controlled Method -> Solution Study -> (This should be whichever study was used to compute the electric field). If you have both the AC/DC Module and the Particle Tracing Module, the following examples are very instructive for coupling external fields to the particle trajectory calculation: Quadrupole Mass Filter: https://www.comsol.com/model/quadrupole-mass-filter-12039 Quadrupole Mass Spectrometer: https://www.comsol.com/model/quadrupole-mass-spectrometer-10653 Best Regards, Chris

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 2016年5月17日 GMT-4 19:39
Thank you for the reply, Christopher.
But I have done something wrong yet. After setting up parameters in Time Dependent Study I have got new problem: particles didn't leave the cathode. Particles have stopped moving. Maybe do I neen to use "Particle Field Interaction"?

Best regards, Mikalai Stolyar
Thank you for the reply, Christopher. But I have done something wrong yet. After setting up parameters in Time Dependent Study I have got new problem: particles didn't leave the cathode. Particles have stopped moving. Maybe do I neen to use "Particle Field Interaction"? Best regards, Mikalai Stolyar

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.