A couple of instructions can be used regardless of the origin.
Gas mixture prepared during the run:
| Command | Short description |
|---|---|
ADD |
Adds/replaces elements of the transport table |
CLUSTER |
Enters the cluster size distribution |
EXTRAPOLATIONS |
Extrapolation of the gas tables |
HEED |
Prepares cluster generation by Heed |
INTERPOLATIONS |
Interpolation method in the gas tables |
MAGBOLTZ |
Magboltz gas mixture (accurate) |
MIX |
Schultz-Gresser gas mixing (approximate) |
PARAMETERS |
Molecular parameters of the gas mixture |
PRESSURE |
Sets the pressure |
TEMPERATURE |
Sets the temperature |
WRITE |
Stores the gas description |
User specified gas mixture:
| Command | Short description |
|---|---|
ADD |
Adds/replaces elements of the transport table |
CLUSTER |
Enters the cluster size distribution |
EXTRAPOLATIONS |
Extrapolation of the gas tables |
GAS-IDENTIFIER |
Adds a label to the gas description |
INTERPOLATIONS |
Interpolation method in the gas tables |
PARAMETERS |
Molecular parameters of the gas mixture |
PRESSURE |
Sets the pressure |
RESET |
Erases gas data entered sofar |
TABLE |
Enters the gas tables |
TEMPERATURE |
Sets the temperature |
WRITE |
Stores the gas description |
Historically, Garfield contains a number of experiment-based gas tables. They remain available for backwards compatibility, but their use is not recommended for new applications:
| Command | Short description |
|---|---|
ARGON-20-ETHANE-80 |
Loads the mixture argon 20\ %, ethane 80\ % |
ARGON-50-ETHANE-50 |
Loads the mixture argon 50\ %, ethane 50\ % |
ARGON-80-ETHANE-20 |
Loads the mixture argon 80\ %, ethane 20\ % |
ARGON-73-METH-20-PROP-7 |
Loads argon 73\ %, CH\<SUB\>4\</SUB\> 20\ %, propanol 7\ % |
CO2 |
Loads data for almost pure CO\<SUB\>2\</SUB\> |
CO2-80-ETHANE-20 |
Loads the mixture CO\<SUB\>2\</SUB\> 80\ %, ethane 20\ % |
CO2-90-ETHANE-10 |
Loads the mixture CO\<SUB\>2\</SUB\> 90\ %, ethane 10\ % |
CO2-90-ISOBUTANE-10 |
Loads the mixture CO\<SUB\>2\</SUB\> 90\ %, isobutane 10\ % |
ETHANE |
Loads data for pure ethane |
ISOBUTANE |
Loads data for pure isobutane |
METHANE |
Loads data for pure methane |
Retrieval of a gas description previously stored:
| Command | Short description |
|---|---|
GET |
Retrieves gas data from a dataset |
General purpose instructions:
| Command | Short description |
|---|---|
OPTIONS |
Plotting and printing of the gas tables |
PLOT-OPTIONS |
Selects plots, sets ranges and log/lin axes |
Additional information on:
For new applications, consider using HEED for ionisation of gas mixtures due to charged particles, MAGBOLTZ for the electron transport properties, and ADD to add ion mobility data, e.g. from the H.W. Ellis et al. papers.
Example:
ARG-50-ETH-50
(Until further notice, the program will use 50\ % argon, 50\ % ethane.)
Additional information on:
The ADD command has 2 formats:
Beware that the WRITE command executes only when the section is left. Therefore, if you modify Magboltz computed gas tables with the ADD command, the modified tables will be written - not the original Magboltz data, no matter where you place the WRITE and ADD statements,
REPLACE is a synonym for ADD. The MERGE command should be used if you wish to combine the existing gas data with data from a gas file.
Format:
ADD item_1 { function_1 | value_1 VS ep_1 [ORDER order_1] } ...
item_2 { function_2 | value_2 VS ep_2 [ORDER order_2] } ...
...
Example:
Global pbar = 3 magboltz argon 91 nitrogen 4 methane 5 ... e/p-range 0.05 135 Vector E_Ar_Ar K_Ar_Ar 0 1.53 8 1.53 10 1.53 12 1.53 15 1.52 20 1.51 25 1.49 30 1.47 40 1.44 50 1.41 60 1.38 80 1.32 100 1.27 120 1.22 150 1.16 200 1.06 250 0.99 300 0.95 400 0.85 500 0.78 600 0.72 800 0.63 1000 0.56 1200 0.51 1500 0.46 2000 0.40Global E_Ar_Ar = E_Ar_Ar/(0.010354*300) Global K_Ar_Ar = K_Ar_Ar*1e-6/pbar add ion-mobility K_Ar_Ar vs E_Ar_Ar extrapolations low-ion-mobility constant high-ion-mobility linear
Magboltz is used to generate an electron transport table. This also sets the E/p scale.
Next, a file is read in that contains mobilities as function of E/N for Ar\<SUP\>+\</SUP\> ions in Ar at a pressure of 1 atm. The data is taken from the literature, in this case Hornbeck '51 and Beaty '68 (for an extensive compilation consult the H. W. Ellis et al. papers). The E/N values are stored in the matrix E_Ar_Ar, while the mobilities are kept in K_Ar_Ar.
The E/N vector is transformed to E/p. The mobility is divided by the pressure, and its units are changed from cm\²/sec.V to cm\²/\μsec.V.
Finally, the mobility is added to the gas tables using the ADD statement.
References:
Additional information on:
The cluster size distribution is not by itself enough to generate clusters along a track. The EXPONENTIAL-SPACING clustering model which uses the distribution entered here, also needs to know the mean number of clusters per cm.
If you use the HEED interface, then you neither need to enter a cluster size distribution nor the cluster spacing. Entering a cluster size distribution and initialising Heed is however allowed. It is only at the TRACK level that you decide which clustering model you are going to use.
Additional information on:
The composition is set by the MAGBOLTZ command and is preserved in gas files (written by WRITE and read with GET). There is therefore no need to use the COMPOSITION command when running Magboltz nor when retrieving Magboltz generated electron transport tables.
The information supplied by this command is only used by the microscopic electron tracking procedures such as DRIFT_MICROSCOPIC_ELECTRON and MICROSCOPIC_AVALANCHE.
This command does not provide the electron transport tables needed by the other electron tracking methods. You will therefore, in general, have to provide electron transport tables (e.g. using TABLE) when using the COMPOSITION statement.
All fractions must be strictly positive. The fractions may add up to any non-zero value - they will be normalised by Magboltz.
Format: see MAGBOLTZ
Example:
composition argon 80 co2 20This will set the gas composition to 80\ % Ar and 20\ % CO\<SUB\>2\</SUB\>.
The EXTRAPOLATIONS command has no effect on extrapolation in 2-dimensional tables, such as those produced by Magboltz when the B field is non-zero. For such tables, polynomial extrapolation is performed with the order set with the INTERPOLATIONS command.
EXTRAPOLATE can be used as synonym for this command.
Format:
EXTRAPOLATIONS item1 method1 item2 method2 ...
Examples:
extrapolate drift: linear, diff: const, town: const extrapolate drift exp
Additional information on:
The MAGBOLTZ and MIX commands set an identification string that contains a description of the gas mixture. It is advisable not to override this string. Instead, one can use the GET_GAS_DATA procedure to obtain the identifier set by these commands, and then add further information to it.
The identification string is displayed in the plots using the COMMENT text representation.
Format:
GAS-IDENTIFIER string
Examples:
GAS-ID "Some gas"
Sets a simple identification string.
temperature 300 K magboltz argon 50 dme 50 *** Ar++ in Ar, T=300 K, error 1 % (Mason McDaniel I, Beaty 68) Vector E_Ar_Ar_2 K_Ar_Ar_2 40 2.49 50 2.47 60 2.45 70 2.42 80 2.39 90 2.37 100 2.34 120 2.28 140 2.23 160 2.19 180 2.15 200 2.11Call get_gas_data(p,t,gasid) Global E_Ar_Ar_2 = p*E_Ar_Ar_2/(0.010354*t) Global K_Ar_Ar_2 = K_Ar_Ar_2*1e-6 add ion-mobility K_Ar_Ar_2 vs E_Ar_Ar_2 extrapolations low-ion-mobility constant high-ion-mobility linear gas-id "{gasid} with Ar<SUP>++</SUP>"
Magboltz is used to compute electron transport properties, and these are complemented with experimental Ar mobility at the same temperature and pressure. The addition is registered in the gas identifier.
The compact gas description contains electron transport property tables, the ion mobility, cluster size and cluster spacing data, Heed initialisation information, SRIM energy loss, range and straggling tables, the pressure and the temperature. GET overwrites all of these.
Since format version\ 8, an attempt has been made to maintain backwards compatibility of file formats. Beware however that older formats will as a rule not contain as much information as the newer versions, which may result in the failure of certain newer commands.
Format:
GET file [member]
Example:
GET gas_data.dat gas2
Additional information on:
The TEMPERATURE and the PRESSURE should be specified before issuing the HEED command. Defaults are assumed if they follow the HEED command.
Neither temperature nor pressure scaling is applied to the cluster information provided by HEED.
The author of Heed, Igor Smirnov, should be contacted for further information about this program.
Format:
HEED [ HYDROGEN fraction ] [ HELIUM-4 fraction ] ...
[ NEON fraction ] [ ARGON fraction ] ...
[ KRYPTON fraction ] [ XENON fraction ] ...
[ NITROGEN fraction ] [ OXYGEN fraction ] ...
[ METHANE fraction ] [ ETHANE fraction ] ...
[ ETHENE fraction ] [ ACETYLENE fraction ] ...
[ PROPANE fraction ] [ ISOBUTANE fraction ] ...
[ NEOPENTANE fraction ] ...
[ WATER fraction ] [ CO2 fraction ] ...
[ DME fraction ] [ NITROUS-OXIDE fraction ] ...
[ AMMONIA fraction ] [ SF6 fraction ] ...
[ CS2 fraction ] ...
[ CF4 fraction ] [ C2F4H2 fraction ] ...
[ C2F5H fraction ] [ C3F8 fraction ]
Example:
pressure {3*760}
Heed argon 50 ethane 50
(If you have a 3\ atm 50/50 argon-ethane mixture in your chamber.)
By default, the gas tables are interpolated using quadratic Newton polynomials. Use this statement if you wish to select splines, lower order polynomials or higher order polynomials.
The interpolation method is ignored if the gas table contains only a single electric field strength.
INTERPOLATE can be used as a synonym for this command.
Format:
INTERPOLATIONS item1 method1 item2 method2 ...
Examples:
interpolate drift-velocity newton 2, long-diffusion newton 1 int townsend spline
Additional information on:
Contrary to the related MIX instruction, Magboltz takes cross sections for non-elastic processes into account. Furthermore, Magboltz is not limited to the 0th and 1st order terms of the spherical harmonics expansion used by MIX. Magboltz does need considerably more calculation time.
In Garfield up to version\ 8, this command gave access to both version\ 1 and version\ 2 of Magboltz. These programs differed by the integration technique use: ANALYTIC-INTEGRATION for version\ 1 and MONTE-CARLO-INTEGRATION for version\ 2. Version\ 1 was to be preferred for pure noble gases and mixtures of exclusively noble gases, without addition of quenchers or other additives. Version\ 2, which became default, was recommended for all other pure gases and for all gas mixtures. Even though these older versions of Magboltz did compute the Townsend and attachment coefficients, one used the Imonte program (from the same author) to compute these with better precision.
From Garfield version\ 9 on, Magboltz version\ 7 and higher is called. This Magboltz version only does Monte Carlo integration. It can be used for gas mixtures both with and without quenchers, even if the program will be slow for the latter. Magboltz version\ 7 includes the Imonte functionality - which is therefore no longer needed.
Since Magboltz takes the magnetic field into account to compute the transport properties, the &MAGNETIC section should precede the gas section. If there is a magnetic field, the program computes a drift velocity vector, otherwise a scalar.
Likewise, TEMPERATURE and PRESSURE statements should be issued before invoking Magboltz. If the temperature has not been specified when Magboltz runs, then a default temperature of 300\ K will be assumed. No scaling will be applied if the temperature is changed later on. The default pressure is 760\ Torr. The transport properties will be scaled according to simple scaling laws if the pressure is modified after the transport properties have been computed. It is not recommended, however, to rely on these scaling laws since these are very approximate.
The author of Magboltz, Steve Biagi, should be contacted for further information about this program.
Format:
MAGBOLTZ [ HYDROGEN frac ] ...
[ DEUTERIUM frac ] ...
[ HELIUM-3-ANISOTROPIC frac ] ...
[ HELIUM-3-ISOTROPIC frac ] ...
[ HELIUM-4-ANISOTROPIC frac ] ...
[ HELIUM-4-ISOTROPIC frac ] ...
[ NEON-ANISOTROPIC frac ] ...
[ NEON-ISOTROPIC frac ] ...
[ ARGON-ANISOTROPIC frac ] ...
[ ARGON-ISOTROPIC frac ] ...
[ KRYPTON-ANISOTROPIC frac ] ...
[ KRYPTON-ISOTROPIC frac ] ...
[ XENON-ANISOTROPIC frac ] ...
[ XENON-ISOTROPIC frac ] ...
[ NITROGEN-ANISOTROPIC frac ] ...
[ NITROGEN-ISOTROPIC frac ] ...
[ OXYGEN frac ] ...
[ OZONE frac ] ...
[ FLUORINE frac ] ...
[ CAESIUM frac ] ...
[ MERCURY frac ] ...
[ METHANE frac ] ...
[ DEUTERATED-METHANE frac ] ...
[ ETHANE frac ] ...
[ ETHENE frac ] ...
[ ACETYLENE frac ] ...
[ PROPANE frac ] ...
[ CYCLOPROPANE frac ] ...
[ PROPENE frac ] ...
[ ISOBUTANE frac ] ...
[ N-BUTANE frac ] ...
[ NEOPENTANE frac ] ...
[ N-PENTANE frac ] ...
[ METHANOL frac ] ...
[ ETHANOL frac ] ...
[ PROPANOL frac ] ...
[ CARBON-MONOXIDE frac ] ...
[ CARBON-DIOXIDE frac ] ...
[ WATER frac ] ...
[ NITRIC-OXIDE frac ] ...
[ NITROUS-OXIDE frac ] ...
[ METHYLAL frac ] ...
[ DME frac ] ...
[ TRIFLUOROMETHANE frac ] ...
[ TRIFLUOROBROMOMETHANE frac ] ...
[ TETRAFLUOROMETHANE frac ] ...
[ TETRAFLUOROETHANE frac ] ...
[ HEXAFLUOROETHANE frac ] ...
[ OCTAFLUOROPROPANE frac ] ...
[ BORON-TRIFLUORIDE frac ] ...
[ SULPHUR-HEXAFLUORIDE frac ] ...
[ AMMONIA frac ] ...
[ CARBON-DISULPHIDE frac ] ...
[ CARBONYL-SULPHIDE frac ] ...
[ HYDROGEN-SULPHIDE frac ] ...
[ GERMANE frac ] ...
[ SILANE frac ] ...
[ REID-STEP frac ] ...
[ MAXWELL-MODEL frac ] ...
[ REID-RAMP frac ] ...
[ [ ELECTRIC-FIELD-RANGE emin emax ] ...
[ N-E ne ] ...
[ LINEAR-E-SCALE | LOGARITHMIC-E-SCALE ] | ...
[ ELECTRIC-FIELD {efield1 efield2 ... | vector} ] ] ...
[ [ ANGLE-RANGE amin amax ] [ N-ANGLE nangle ] | ...
[ ANGLE {angle1 angle2 ... | vector} ] ] ...
[ [ B-FIELD-RANGE bmin bmax ] [ N-B nb ] | ...
[ B-FIELD {bfield1 bfield2 ... | vector} ] ] ...
[ NOPLOT-DISTRIBUTION-FUNCTIONS | PLOT-DISTRIBUTION-FUNCTIONS ] ...
[ NOPLOT-CROSS-SECTIONS | PLOT-CROSS-SECTIONS ] ...
[ NOKEEP | KEEP ] ...
[ NOPRINT | PRINT ]
[ ANALYTIC-INTEGRATION ...
[ SECOND-ORDER-TERMS | FIRST-ORDER-TERMS | ORDERS n ] ...
[ NOITERATE-ALPHA | ITERATE-ALPHA ] ...
[ SWITCH [alpha/pressure] | NOSWITCH ] ...
[ F0-TRANSVERSE-DIFFUSION | ...
H1-TRANSVERSE-DIFFUSION | ...
MEAN-ENERGY-TRANSVERSE-DIFFUSION ] ...
[ F0-LONGITUDINAL-DIFFUSION | ...
H1-LONGITUDINAL-DIFFUSION | ...
G0-LONGITUDINAL-DIFFUSION ] | ...
[ MONTE-CARLO-INTEGRATION ...
[ COLLISIONS ncoll ] ] ] ...
[ MOBILITY mob ]
Example:
magboltz argon 50 ethane 50
(You've a mixture of 50\ % argon and 50\ % ethane in your chamber, and you trust the default settings for the electric field range, for the magnetic field and for the angles between E and B field as well as the default precision.)
Additional information on:
The MATERIAL command takes a chemical composition as argument,
Format:
MATERIAL [ALUMINIUM n] [ARGON n] [CARBON n] ...
[FLUORINE n] [HELIUM n] [HYDROGEN n] ...
[KRYPTON n] [LITHIUM n] [NEON n] ...
[NITROGEN n] [OXYGEN n] [SILICON n] ...
[SULPHUR n] [XENON n] ...
DENSITY density ...
WORK work ...
[FANO fano]
Example:
material C 12 H 22 O 11 density 1.59 work 3
Which would fill your device with sucrose, ordinary sugar.
Additional information on:
This only works if the current data and the data in the file have at least 2 of the following 3 axes in common: the set of electric field values, the set of angles between E and B and the set of magnetic field values. This condition is trivially met if the current gas data and the data in the file both concern a zero magnetic field situation.
If precisely 2 of the 3 axes coincide, then the merged data will contain only the transport properties which are found in both the current data and in the file.
If all 3 axes coincide, then the merged data will contain all the transport properties that are found in either the current data or the file.
Also the ADD command adds transport properties to the gas tables, under somewhat different conditions.
Contrary to the GET command, MERGE can not read files written in earlier formats. The way out consists in reading old-format files with GET, writing them out using WRITE and then using the file thus obtained for the merge.
Format:
MERGE file [member] [KEEP-OLD | REPLACE-OLD]
Example:
get "low.gas" merge "high.gas"
Additional information on:
The main limitation of this method is that it neglects ionisation effects and that it treats excitation inaccurately. This implies that the results are not valid for large E/p values, i.e. close to the electrodes.
Another limitation is that these calculations neglect the magnetic field - this is not an inherent limitation of the method, but there is no intention to invest further effort in this instruction. Garfield nowadays has an interface to the MAGBOLTZ program of Steve Biagi which is far superior in accuracy to this instruction.
Format:
MIX [ ARGON frac ] [ HELIUM frac ] ...
[ METHANE frac ] [ ETHANE frac ] ...
[ NEON frac ] [ NITROGEN frac ] ...
[ ISOBUTANE frac ] [ XENON frac ] ...
[ CO2 frac ] [ METHYLAL frac ] ...
[ KRYPTON frac ] [ AMMONIA frac ] ...
[ MINIMUM-ENERGY emin ] ...
[ MAXIMUM-ENERGY emax ] ...
[ STEPSIZE-ENERGY estep ] ...
[ CRITICAL-F0-FRACTION frcrit ] ...
[ E/P-RANGE epmin epmax ] ...
[ N-E/P n ] ...
[ LINEAR-E/P-SCALE | LOGARITHMIC-E/P-SCALE ] ...
[ PLOT-F0 | NOPLOT-F0 ] ...
[ PLOT-ENERGY-LOSS | NOPLOT-ENERGY-LOSS ] ...
[ PLOT-CROSS-SECTION | NOPLOT-CROSS-SECTION ] ...
[ PLOT-PATH | NOPLOT-PATH ] ...
[ PRINT-TABLES | NOPRINT-TABLES ] ...
[ MOBILITY mob ] ...
[ TOWNSEND-COEFFICIENT \α/p ] ...
[ ATTACHMENT-COEFFICIENT \η/p ]
Example:
mix argon 50 ethane 50
The gas in your chamber will be 50\ % argon and 50\ % ethane.
Additional information on:
Format:
OPTIONS [NOGAS-PLOT | GAS-PLOT] ...
[NOGAS-PRINT | GAS-PRINT]
Examples:
plot-options drift-velocity nodiffusion notownsend opt gas-plot nogas-print
Requests a plot of the drift velocity. If cluster data has been entered, then also a cluster plot will be made (this is default) but diffusion and multiplication graphs are not shown. Using further PLOT-OPTIONS options, one could have fixed for instance the scale of the drift velocity plot.
&GAS magboltz argon 70 dme 30 opt gas-print nogas-plot >ArDME.print &MAIN >
MAGBOLTZ is called to compute transport properties for a 70/30 mixture of argon and DME. The transport tables are printed when leaving the section - note the use of the &MAIN command to close the gas section. They do not appear on the screen, but are output to the file ArDME.print.
Additional information on:
Originally, most of this data was only used for a simple Landau-based backup estimate of the cluster size distribution if the CLUSTER size distribution is not known from data and if the HEED model can not be used.
Some of the parameters are however used for other purposes too:
Format:
PARAMETERS [ A a ] ...
[ Z z ] ...
[ RHO density ] ...
[ E-PAIR epair ] ...
[ E-MOST-PROBABLE emprob ] ...
[ MEAN mean_number_of_clusters ] ...
[ TRANSVERSE-ION-DIFFUSION {THERMAL | sigma_T} ] ...
[ LONGITUDINAL-ION-DIFFUSION {THERMAL | sigma_L} ]
As shown in the format description, several lines may be used although a single line is perfectly acceptable as well.
Example:
PARA MEAN 20
This format could be used if you wish to compute arrival time spectra and enter the cluster size distribution with CLUSTER.
Additional information on:
Several plots may be modified in a single statement.
Use DRIFT_VELOCITY and related procedures to have full control over the presentation of the plot.
Format:
PLOT-OPTIONS [plot [options]] ...
Example:
plot-options drift lin-x log-y nodiff nocluster
(Requests a linear E/p axis and a logarithmic drift velocity axis, the opposite of the default. The diffusion coefficients and the cluster size distribution are not plotted.)
Additional information on:
The pressure is used by the gas mixing instructions MIX and MAGBOLTZ as well as by HEED. Please be sure to specify the pressure before issuing these commands.
If you specify the pressure after a mixing command, then the tables will be prepared for standard atmospheric pressure and the conversion to the pressure you specify will be done by relying on the simple scaling laws.
Format:
PRESSURE pressure [unit]
Example:
pressure 2 bar
Additional information on:
A selective reset is performed if any items are listed, otherwise all gas data is deleted.
Format:
RESET [item1] [item2] ...
Additional information on:
In order to estimate electron deposition from the SRIM model, Garfield will need the A and Z of the gas to be entered with the PARAMETERS statement. The SRIM files do not seem to contain this information.
SRIM files contain a density estimate and, when reading such a file, the gas density, if entered on beforehand with the PARAMETERS statement, would be overwritten. It is therefore advisable to issue the PARAMETERS command after the SRIM command if the density as estimated by SRIM is not considered reliable. Please note that the a density entered with the PARAMETERS statement will not affect the range estimated by SRIM.
The energy loss, range and straggling parameters will be plotted, when the gas section is being left, if the GAS-PLOT option is switched on.
The SRIM tables are included in the files that are written by the WRITE command and read by the GET command.
Use the SRIM option of the TRACK command to produce clusters based on this model.
Comments, and in particular comparisons with experimental data, as well as suggestions for improvement are invited.
Format:
SRIM FILE file ...
WORK-FUNCTION work ...
FANO-FACTOR fano
Example:
srim file="SRIMHeInCF.dat" work=40A file with SRIM output for \α particles traversing He/CF\<SUB\>4\</SUB\> is read, and we assume a work function of 40\ eV.
Additional information on:
Each of the table entries can either be tabulated or be computed from a parametrisation. In either case, the quantities that obey simple pressure scaling laws, have to be entered multiplied by the appropriate power of the pressure.
All tabulated entries must be specified at a common set of E/p values, which must itself be listed in the table if at least one transport property is tabulated. Use ADD if the data that you wish to use for one or more entries, is tabulated at a different set of E/p values.
The order of the tabulated entries is indicated on the TABLE line by listing the names of the entries in the same sequence as in the table. The entry names should not be followed by parametrisations. The place of the E/p values in the table should be indicated by 'E/P'. There is no preferred order of the entries.
If you opt for a parametrised form for one or more entries, then functions have to follow the names of the entries that are to be parametrised. The parametrisations that you enter are not stored as functions, rather they are evaluated at the E/p, angle(E,B) and B values of the table. The list thus obtained will be interpolated when transport properties are required, like for tabulated entries.
If all entries are entered in a parametrised form, then you can either establish the list of E/p values by tabulating them or by specifying an electric_field range.
You have the possibility to create tables with a dependence on the angle between E and B, as well as on the magnetic_field, provided a magnetic field is present in the chamber.
Format:
TABLE [ E/P ] ...
[ DRIFT-VELOCITY [ function ] ] ...
[ BTRANSVERSE-VELOCITY [ function ] ] ...
[ ExB-VELOCITY [ function ] ] ...
[ ION-MOBILITY [ function ] ] ...
[ ION-DISSOCIATION-COEFFICIENT [ function ] ] ...
[ LORENTZ-ANGLE [ function ] ] ...
[ LONGITUDINAL-DIFFUSION-COEFFICIENT [ function ] ] ...
[ TRANSVERSE-DIFFUSION-COEFFICIENT [ function ] ] ...
[ TOWNSEND-COEFFICIENT [ function ] ] ...
[ ATTACHMENT-COEFFICIENT [ function ] ] ...
[ DUMMY [ function ] ] ...
[ E/P-RANGE epmin epmax ] [ N-E/P nep ] ...
[ LOGARITHMIC-E/P-SCALE | LINEAR-E/P-SCALE ] ...
[ [ B-RANGE bmin bmax ] [ N-B nb ] | ...
[ B-FIELD b ] ] ...
[ [ ANGLE-RANGE amin amax ] [ N-ANGLE nangle ] | ...
[ ANGLE angle ] ]
This line is followed by tables for those items that are not functions. The end of the table is signalled by a blank line.
Example:
table drift=100*ep, diff, e/p 0.3 0.1 0.1 0.2 0.1 0.5 0.2 1.0 0.3 2.0// Note that the preceding line is intentionally left blank
The drift velocity is entered as the function 100*E/p which is evaluated at the E/p values listed in the second column. The longitudinal diffusion is listed in the first column. The ion mobility, the Lorentz angle and the Townsend and attachment coefficients are not specified. Note the blank line at the end of the table.
Additional information on:
The temperature is used by the gas mixing instructions (MIX and MAGBOLTZ) and also by HEED. Please be sure to specify the temperature before issuing these commands.
The temperature is not needed if both the transport properties and the clustering properties have been entered via tables.
Garfield applies, if required, pressure scaling of the transport properties but does not apply temperature scaling laws.
Format:
TEMPERATURE temp [unit]
Example:
TEMPERATURE 300 K
For room temperature.
Additional information on:
Interface written by James Butterworth.
Format:
TRIM LAYER layer ...
ION ion ...
WORK-FUNCTION work ...
FANO-FACTOR fano ...
RANGE-FILE range ...
EXYZ-FILE exyz
Additional information on:
The use of this instruction is strongly recommended when you compute the electron transport properties with MAGBOLTZ or with MIX, both of which consume a lot of CPU time. WRITE is not of interest if you enter the transport parameters of your gas description with a TABLE statement.
The dataset contains initialisation information for Heed, which will automatically be performed when re-reading the file with GET. Similarly, SRIM energy loss, range and straggling tables are included in the compact format gas datasets.
The format of the compact dataset is subject to modification and backwards compatibility is not guaranteed. Compact datasets that can no longer be read and that are of value, can be sent to the author of Garfield for recovery.
Files written with WRITE should in principle not be edited. These files are also not intended to serve as easily legible tables. Use the GAS-PRINT option or procedures like DRIFT_VELOCITY to obtain legible tables.
Writing takes place while the section is being left, not when the WRITE command is issued. Use e.g. &MAIN to close the section. The statement can appear at any place in the gas section.
Format:
WRITE [DATASET] file [member] [[REMARK] remark]
Example:
Global gas_file `Ar_70_iso_30.gas`
Global gas_member `exb`
Global p 760
&GAS
Call inquire_member(gas_file,gas_member,`gas`,exist)
If exist Then
get {gas_file,gas_member}
Else
write {gas_file,gas_member}
pressure {p} Torr
magboltz argon 70 isobutane 30 ...
angle-range 0 10 n-angle 6 ...
b-range 0.4 1.2 n-b 5 ...
e-range 100 300000 n-e 25 ...
coll 25
Endif
Since Magboltz consumes a large amount of CPU time, we use the WRITE command to store the gas tables. When the same input file is run next time, the INQUIRE_MEMBER procedure will detect that the gas tables already exist and a GET is issued instead of a MAGBOLTZ command.
Additional information on:
Formatted on 21/01/18 at 16:55.