STEP 1: Specifying Input Parameters
Plasma:
Plasma-producing gas
Plasma pressure (bar)
Cathode:
Material
Radius (m)
Height (m)
Temperature of the base (K)
Radiation:
.t.
.f.
Insulated lateral surface:
.t.
.f.
Thermionic emission parameters will be taken from the internal database:
Yes
No
By default, the code employs (constant) values of the work function and the pre-exponential factor in the Richardson-Dushman formula for the specified cathode material taken from the internal database. Alternatively, you may specify these values by yourself. (This option is particularly useful while working with doped materials, e.g., thoriated tungsten.) A further option, which is available in the case where the cathode material is W and the plasma-producing gas is one of the mixtures Na-Hg or Cs-Hg, is to make the code evaluate the work function taking into account its variation owing to the formation of a monolayer of alkali metal atoms on the surface. Values that appear in the fields "Work function" and "Pre-exponential factor in the Richardson-Dushman formula" have no effect if you choose this option.
Work function (eV):
Pre-exponential factor in the Richardson-Dushman formula (A m
^{-2}
K
^{-2}
):
Variability of the work function:
.t.
.f. (W cathode and NH or CH plasmas)
Content of sodium:
(NH, MH, and XH plasmas)
Content of thallium:
(MH and XH plasmas)
Content of dysprosium:
(MH and XH plasmas)
Content of scandium:
(MH and XH plasmas)
Content of cesium:
(CH, MH, and XH plasmas)
Content of zinc:
(XH plasma)
Content of indium:
(XH plasma)
Content of thorium:
(XH plasma)
Content of iodine:
(XH plasma)
Show prompts:
.t.
.f.
Time limit:
distributions of q and Te:
.t.
.f.
STEP 2: Generating a starting-point solution
The default numerical grid will be used (recommended):
Yes
No
The code employs a uniform rectangular numerical grid of the second order of accuracy, which is by default 300x30. This default grid will suit your needs in most cases. If you choose to refine the grid by increasing the number of steps, read first Section 4.3 of the tutorial. Keep in mind that the changes will take effect when the starting-point solution starts being generated.
Number of steps of the numerical grid in the axial direction:
max value: 999
Number of steps of the numerical grid in the radial direction:
max value: 999
Near-cathode voltage corresponding to the desired starting point:
V
Generating starting-point solution automatically:
Yes
No
Number of steps in which a starting-point solution will be generated automatically:
Generating starting-point solution from a manually-defined initial approximation:
Yes
No
Temperature at the center of the front surface of the cathode:
K
Temperature at the edge of the cathode:
K
Spot radius:
m
Damper:
Generate a starting-point solution
STEP 3: Performing Simulations
Near-cathode voltage corresponding to the starting point:
V
Near-cathode voltage corresponding to the last point:
V
Number of steps between the starting and last points:
Number of the bifurcation point (enter -1 if you are not interested in stability of the diffuse mode or bifurcations of 3D spot modes):
Do you want to use the solution corresponding to the last point as a starting point for further calculations?
Yes
No
Program output
Integral characteristics
Distributions