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Variable | Meaning | Value, Unit |
---|---|---|
ANGLE_EB | Angle between E and B | degrees |
B | Magnetic field | Tesla |
BOLTZMANN | Boltzmann constant | 1.380658E-23 J/K |
ECHARGE | Electron charge | 1.60217733E-19 C |
EP | E/p | V/cm.Torr |
P | Pressure | Torr |
T | Temperature | K |
The magnetic field related quantities, ANGLE_EB and B, are to be used only when there is a magnetic field.
Example:
See the FIT_EXPONENTIAL procedure.
quantity | scaling | enter |
---|---|---|
drift velocity | v vs E/p | v |
ion mobility | mu vs E/p | mu |
diffusion coefficients | sigma.sqrt(p) vs E/p | sigma.sqrt(p) |
Townsend coefficient | alpha/p vs E/p | alpha/p |
Attachment coefficient | beta/p vs E/p | beta/p |
Lorentz angles | - | angle |
Example: the diffusion coefficient varies approximately with pressure according to the formula:
sigma(p=p1)=sigma(p=p0)*sqrt(p0)/sqrt(p1)
hence sigma.sqrt(p) is approximately constant.
Assigning the transverse diffusion:
table e/p trans-diff long-diff 1 0.1 0.1 2 0.1 0.2 3 0.1 0.3
Not assigning the transverse diffusion:
table e/p dummy long-diff 1 0.1 0.1 2 0.1 0.2 3 0.1 0.3
Alternatively, you could have kept the original table followed by a RESET TRANS-DIFF command.
This parameter is relevant only if E/p is not tabulated i.e. if the table is composed exclusively of computed entries. There is in that case no E/P keyword on the TABLE instruction line.
You may specify that you wish linearly or logarithmically spaced points, and you may also select the number of points.
[By default: 100 to 100000 V/cm in 20 logarithmic steps.]
Specifying such a range is valid only if there is a magnetic field.
Even though specifying an angle range is useful mainly if you have at least one computed table entry which depends on the angle, you may also specify the range for a tabulated table. Doing this forces the table to have room for B or angle dependent entries, which you can later add with the ADD command.
For defaults and further considerations, see the choice of ANGLE for the MAGBOLTZ command.
Specifying such a range is valid only if there is a magnetic field.
Even though specifying an magnetic field is useful mainly if you have at least one computed table entry which depends on this field, you may also specify the range for a tabulated table. Doing this forces the table to have room for B or angle dependent entries, which you can later add with the ADD command.
For defaults and further considerations, see the choice of B-FIELD for the MAGBOLTZ command.
Formatted on 0100-08-24 at 22:37.