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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 |
Built-in gas mixtures with fixed proportions:
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 %, CH4 20 %, propanol 7 % |
CO2
| Loads data for almost pure CO2 |
CO2-80-ETHANE-20
| Loads the mixture CO2 80 %, ethane 20 % |
CO2-90-ETHANE-10
| Loads the mixture CO2 90 %, ethane 10 % |
CO2-90-ISOBUTANE-10
| Loads the mixture CO2 90 %, isobutane 10 % |
ETHANE
| Loads data for pure ethane |
ISOBUTANE
| Loads data for pure isobutane |
METHANE
| Loads data for pure methane |
PRESSURE
| Sets the pressure |
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 |
Please ensure, with the GAS-PRINT and GAS-PLOT options, that the tables agree with what you think is reasonable.
These mixtures have fixed proportions, use MAGBOLTZ or MIX to obtain tables for arbitrary proportions.
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.
Format:
ADD item_1 { function_1 | value_1 VS ep_1 [ORDER order] } ...
Example:
Global pbar = 3 magboltz argon 91 nitrogen 4 methane 5 ... e/p-range 0.05 135 Read-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 extrapolation 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+ 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 is changed from cm2/sec.V to cm2/microsec.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 clustering model based on the distribution entered here, also need to know the cluster spacing, which can be set with the MEAN keyword of the PARAMETERS command.
If you use the HEED interface, then you probably 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 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.
Format:
EXTRAPOLATIONS item1 method1 item2 method2 ...
Examples:
EXTR DRIFT: LINEAR, DIFF: CONST, TOWN: CONST EXTR DRIFT EXP
Additional information on:
Format:
GAS-IDENTIFIER string
Example:
GAS-ID "Some gas"
The compact gas description contains electron transport property tables, the ion mobility, cluster size and cluster spacing data, Heed initialisation information, the pressure and the temperature. GET overwrites all of these.
Format:
GET dsname [member]
Example:
GET gas_data.dat gas2
Additional information on:
The temperature and the pressure should be specified before issuing the HEED command. See TEMPERATURE and PRESSURE for default settings.
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 [ ARGON fraction ] [ HELIUM-4 fraction ] ... [ NEON fraction ] [ XENON fraction ] ... [ KRYPTON fraction ] [ METHANE fraction ] ... [ ETHANE fraction ] [ ETHENE fraction ] ... [ ACETYLENE fraction ] [ ISOBUTANE fraction ] ... [ PROPANE fraction ] [ NEOPENTANE fraction ] ... [ HYDROGEN fraction ] [ NITROGEN fraction ] ... [ WATER fraction ] [ CO2 fraction ] ... [ CF4 fraction ] [ OXYGEN fraction ] ... [ DME fraction ] [ NITROUS-OXIDE fraction ] ... [ AMMONIA fraction ]
Example:
pressure {3*760} Heed argon 50 ethane 50
(If you have a 3 atm 50/50 Argon-ethane mixture in your chamber.)
Format:
INTERPOLATIONS item1 method1 item2 method2 ...
Examples:
INTERP DRIFT-VELOCITY NEWTON 2, LONG-DIFFUSION NEWTON 1 INT TOWNSEND SPLINE
Additional information on:
Since Magboltz takes the magnetic field into account to compute the transport properties, the &MAGNETIC section should precede the gas section.
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 [ ARGON frac ] [ HELIUM-3 frac ] ... [ HELIUM-4 frac ] [ NEON frac ] ... [ XENON frac ] [ KRYPTON frac ] ... [ METHANE frac ] [ ETHANE frac ] ... [ ETHENE frac ] [ ACETYLENE frac ] ... [ NITROGEN-A frac ] [ NITROGEN-B frac ] ... [ AMMONIA frac ] [ OXYGEN frac ] ... [ ISOBUTANE frac ] [ WATER frac ] ... [ CO2 frac ] [ METHYLAL-HOT frac ] ... [ METHYLAL-COLD frac ] [ PROPANE frac ] ... [ NEOPENTANE frac ] [ CF4 frac ] ... [ DME frac ] [ NITRIC-OXIDE frac ] ... [ NITROUS-OXIDE frac ] ...[ E/P-RANGE epmin epmax ] [ N-E/P nep ] ... [ LINEAR-E/P-SCALE | LOGARITHMIC-E/P-SCALE ] ... [ ANGLE-RANGE amin amax ] [ N-ANGLE nangle ] ... [ NOPLOT-DISTRIBUTION-FUNCTIONS | ... PLOT-DISTRIBUTION-FUNCTIONS ] ...
[ 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 ] ...
[ MOBILITY mob ]
Example:
magboltz argon 50 ethane 50
(The gas in your chamber will be 50 % Argon and 50 % Ethane.)
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 wires.
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 superior in accuracy to this instruction. See MAGBOLTZ.
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 alpha/p ] ... [ ATTACHMENT-COEFFICIENT beta/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]
Example:
OPT NOG-PL G-PR
Additional information on:
The mean number of clusters is used if the clustering model you plan to choose with the TRACK command, is based on the cluster size distribution entered with CLUSTER.
The rest of the data is only used for a simple backup estimate of the cluster size distribution if neither a CLUSTER nor a HEED statement has been issued.
Format:
PARAMETERS [A a] [Z z] [RHO density] [E-PAIR epair] ... [E-MOST-PROBABLE emprob] ... [MEAN mean_number_of_clusters] ... [TRANSVERSE-ION-DIFFUSION sigma_T] ... [LONGITUDINAL-ION-DIFFUSION 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) and also 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:
Format:
RESET
Each of the table entries (drift velocity, ion mobility, Lorentz angle, diffusion coefficients, Townsend and attachment coefficients) can either be tabulated after the TABLE line, or be given as a parametrisation on the TABLE line.
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 (such as DRIFT-VELOCITY) in the same sequence as in the table. The entry names should not be followed by parametrisations. The place of the E/p values should be indicated by 'E/P'. There is no prefered order of the entries.
The entries are interpolated, and if necessary extrapolated, using methods that can be set with the INTERPOLATIONS and EXTRAPOLATIONS statements.
Parametrisations should be functions of the symbolic parameter EP, which equals E/p. They should be entered by placing the name of the entry (e.g. LORENTZ-ANGLE) before the function.
The parametrisations that you enter are not stored as functions, rather they are evaluated at the E/p values in the table and the list thus obtained will be interpolated when transport properties are required, like for tabulated entries.
If all entries are entered in parametrised form, then you can either establish the list of E/p values by tabulating them after the TABLE statement, or use the RANGE and N keywords. These keywords are ignored if at least one entry is tabulated.
Quantities that obey simple pressure scaling laws, have to be entered multiplied by the appropriate power of the pressure.
Format:
TABLE [E/P] ... [DRIFT-VELOCITY [drift]] ... [ION-MOBILITY [mobility]] ... [LORENTZ-ANGLE [angle]] ... [LONGITUDINAL-DIFFUSION-COEFFICIENT [diff]] ... [TRANSVERSE-DIFFUSION-COEFFICIENT [diff]] ... [TOWNSEND-COEFFICIENT [townsend]] ... [ATTACHMENT-COEFFICIENT [attach]] ... [DUMMY [dummy]] ... [RANGE epmin epmax] [N nmax]
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
(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:
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.
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 however be sent to the author of Garfield for recovery.
Files written with WRITE should in principle not be edited. These files are also not meant to be easily readable, 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. The statement can appear at any place in the gas section.
Format:
WRITE DATASET dsname [member] [REMARK remark]
Examples:
WR DATA 'vaxgarf"garfield lasagna"::[garfield]gas.dat' REM "Test gas"
(The keywords DATASET and REMARK are required in this example since the member is omitted. The single quotes are needed because of the double quotes in the remote login string and also because of the two colons.)
Additional information on:
Formatted on 0103-05-16 at 14:04.