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The sum of the fractions is normalised - in the examples, fractions usually add up to 1 or to 100, but this is not mandatory.
[Each fraction is 0 by default.]
The electric field E is expressed in V/cm, p in Torr.
[By default 10/p to 100000/p.]
[By default 20.]
[Logarithmic by default.]
Magboltz will, if B is non-zero, by default be asked to compute tables of the transport properties for a 2-dimensional grid of E/p vs the angle between E and B. The density and range of the grid along the E/p axis is set with N-E/P and E/P-RANGE, while the density and range along the angles is set with N-ANGLE and ANGLE-RANGE.
If your chamber is such that E is always perpendicular to B, then it is advisable to centre the ANGLE-RANGE on 90 degrees, e.g. [80,100], and set N-ANGLE to 1. This will generate a 1-dimensional table for which you have greater control over the INTERPOLATIONS and EXTRAPOLATIONS methods.
If E is not perpendicular to B, then it may in rare cases be sufficient to compute the transport parameters for a limited range of the angle between E and B. Since the dependence on the angle tends to be smooth, this practice is not recommended.
This parameter is meaningful only if there is a magnetic field.
[The default range is 0 to 180 degrees.]
Sets the number of angles between the E and B field for which Magboltz will compute an electron transport table.
A setting of 1 forces the table to be 1-dimensional even if there is a magnetic field. This is useful if E and B are perpendicular everywhere in the chamber. Settings other than 1 and the default are not recommended.
[By default: 7.]
Keep in mind that Magboltz only computes F2 and F3 on request: to get F2 and F3 you need to request SECOND-ORDER-TERMS (or ORDERS 2) and for a reasonably accurate F3 you should specify ORDERS 3. Both are incompatible with the option ITERATE-ALPHA which enables a more precise computation of the Townsend coefficient.
F0 is plotted with representation FUNCTION-1, F1 as FUNCTION-2, F2 as FUNCTION-3 and F3 as FUNCTION-4.
This option potentially generates a lot of output.
The option is off by default.
Values larger than 1 are not compatible with ITERATE-ALPHA, this setting is overruled by the SWITCH option.
[Default: n=2, equivalent to SECOND-ORDER-TERMS.]
SWITCH overrules this selection.
HIGH-PRECISION is synonymous to SECOND-ORDER-TERMS.
[This is the default order, but is overruled by SWITCH.]
LOW-PRECISION is synonymous to FIRST-ORDER-TERMS.
[The default is SECOND-ORDER-TERMS.]
[This is not default.]
If alpha/pressure is smaller than the threshold, the quantities are computed with SECOND-ORDER-TERMS, NOITERATE-ALPHA
Otherwise, they are computed with FIRST-ORDER-TERMS, ITERATE-ALPHA.
This guarantees that the drift velocity, diffusion and Lorentz angle are accurate at low field values, which is where they matter most, whereas the Townsend coefficient is accurate at higher field values, at the price of a somewhat reduced accuracy for the other quantities.
[This option is default, alpha/pressure is set to 50/pressure.]
These formulae are only valid when the approximation that the longitudinal and transverse diffusion are equal is true. This is of course never true, but one can get a correction to the longitudinal diffusion from the ratio of the longitudinal to transverse diffusion without the magnetic field in the given gas at the E-field of interest. [from Steve Biagi]
These diffusion coefficients are obtained when you specify F0-TRANSVERSE-DIFFUSION, H1-TRANSVERSE-DIFFUSION, F0-LONGITUDINAL-DIFFUSION and H1-LONGITUDINAL-DIFFUSION. The correction to the longitudinal diffusion is applied, using the G0 estimate of the longitudinal diffusion.
F0-TRANSVERSE-DIFFUSION is default.
This format only allows for mobilities that are constant or depend in a simple way on E/p. In the latter case, the argument of MOBILITY should be a function with EP as variable.
ADD provides a similar functionality, and can in addition be used if the mobility is available in tabular form.
The unit of mobility in Garfield is cm2/microsec.V.
[By default: no mobility.]
Formatted on 0099-12-08 at 15:52.