In this Data form, the user can enter the gas mixture, pressure (pr, in torr) and temperature (Tg, in K), the dimensions of the simulation domain (Xmax, Ymax, and Zmax, in cm), and the secondary emission coefficients g1, g2, g3, corresponding to the different ions of the mixture. nx, ny, nz are the number of grid intervals in the x, y and z directions (the electric potential is defined at the nods, i.e. on a (nx+1,ny+1,nz+1) grid.
Checking
the box Initialization sets all arrays to their initial values.
If Initialization is not checked, numerical calculations begin using
values for arrays in the file res2d.out.
In the Control form, the user defines the frequency of writing the results on the screen (Run Bar, see below). The second parameter is the frequency of writing the res2d.out file (default is every 200 time step). The third parameter defines the frequency of writing in intermediate files Resxx.res which can be post-processed later (e.g. using the SIPDP-3D PlayBack feature). This frequency can be defined in terms of number of time steps or in time intervals. The file naming scheme is Res01.res, Res02.res,...Res02.res where the numbering is reset to 0 when the initialization corresponding box is checked (otherwise, the program detects the existence of previous Resxx.res files in the directory and continues the numbering from the last one. Go to the Play Back page for more details on the Play Back mode. In SIPDP-3D, the Resxx.res files are stored in binary format, in the binary subdirectory of the RUN directory
The CFL parameter can be used to adjust the time step. The time step during the current pulse, when the plasma is present, is automatically adjusted. In the prebreakdown phase or after the current pulse, the time step is controled by the CFL parameter . The default value is 500 and is a reasonable value. The 500 value is slighlty more accurate, but larger values can be used if one is not concerned by the accuracy during the prebreakdown phase (the delay to breakdown becomes less accurate when this parameter is larger)
The acceleration parameter can also be modified by the user. This parameter sets up the value of the integration time step. The largest values correspond to larger integration time step (faster execution). However for better accuracy, the recommended parameter is 3 default value). The first value ("0") corresponds to no acceleration i.e. to explicit integration of the continuity equations.
The last choice of the acceleration parameter ("ramp") allows very large time steps and should be used only for quasi-steady state situation like for example in the set-up period of the driving scheme of a PDP, where the voltage is slowly increased or decreased (slope on the order of V/ms), and the discharge stays in a Townsend regime.
Only "Symmetry" boundary conditions can be used in this version..
When the Initialization box is checked, the programs starts with a uniform density of electrons and ions defined in this form. The default value (see the menu above) of the initial density is 107 cm-3.
The user can also run the simulation using a uniform production of electrons and ions ("source") in the volume of the cell. This is a supplementary source term of the electron and ion continuity equations and may represent, for example, the generationof electrons and ions due to other processes than electron impact ionization of atoms in the ground state (for example, generation of electrons and ions due to neighbouring cells, photoemission, etc...). Adding this source term may be necessary when studying the ramp voltages used for priming before addressing.
The applied voltage waveform is defined in this menu. Multipulse AC corresponds to a sequence of AC pulses (with a zero or finite rise time). Multipulse AC/RF corresponds to a combination of AC and RF pulses. Breakdown can be used to automatically calculate breakdown voltages and Paschen curves.
The Multipulse AC, AC/RF and the breadown options are chosen by clicking on the corresponding rectangular push buttons. The user must then fill in the proposed form. The different forms are described below:
Each line of this table corresponds to a given time interval (given in microseconds). The voltages (in Volts) applied to each electrode during the time intervals are defined in the columns. The numbering of the electrode voltages (V1, V2, V3 ...) is made in the following order of the sides of the simulation domain: West, East, South, North, Bottom, Top (see Electrode Numbering and Geometry).
If there are three lines in the table, the entry in the box between End after and pulses should be 3.
A sequence of pulses can be repeated several times (see the Repeat sequence line) in a straightforward way.
When the option Step is chosen, the rise time of the voltage pulse is practically zero (equal to one time step). The time column (T (mms)) contains the duration of each voltage pulse (in microseconds). An example of the Step option is given in the table below.
When the option Linear is chosen, it is possible to define a non zero rise time. In that case, for a time interval given in line k , the voltage is supposed to increase linearly between the voltage value given at line k and the voltage value given at line k+1, for each voltage column (i.e. each electrode). The time interval given on the last line is therefore not used. An example of the Linear option is given below. This example is similar to the one above, but with rise times and decay times of 300 ns between pulses.
When the MultiPulse AC/RF option is chosen, two forms are successively presented to the user. The first one is identical to the one of the MultiPulse AC option described above and corresponds to the AC part of the applied voltage. When the MultiPulse AC form is filled in, a second form containing information about the RF part of the applied voltage is presented to the user. This form is shown below. The number of lines is identical to the one of the MultiPulse AC form and cannot be changed. The frequency of the sinusoidal voltage must be indicated in MHz. Each column contains the amplitude of the RF voltage applied to each electrode during a given time interval.
The Breakdown option is not available in this version.
