Viz Glow Training Module Plasma Modeling With Viz

Viz. Glow Training Module Plasma Modeling With Viz. Glow: Understanding Gasact and Surfact File Formats 1301 S. Capital of Texas Highway Suite B-122 Austin, Texas 78746 www. esgeetech. com March 2015

2 COPYRIGHT AND CONFIDENTIALITY STATEMENT Copyright © (2007 -2015) Esgee Technologies, Inc. All rights reserved. This manual accompanies software that is provided to users under a license agreement. This manual can also be provided under a non-disclosure agreement and is subject to restrictions on confidential information under such an agreement. The manual contains proprietary information and may not be disclosed to a third party not covered by the license agreement or a non-disclosure agreement. No part of this manual may be reproduced in any form or by any means without express written permission from Esgee Technologies, Inc.

3 Gasact and Surfact File Formats

4 Introduction Gas and surface chemistry specifications § Any plasma problem solved using Viz. Glow requires specification of chemistry § Chemistry files used here are included with the Examples package, and with the Over. Viz Release Chemistry Database § There are three basic files that make up a chemistry specification: § Gas phase chemistry (. phs) § Surface chemistry (. phs) § Species database (. dbs) § Gas phase chemistry is handled by Gasact § Surface chemistry is handled by Surfact Preliminary Dialog while creating a new project

5 Gasact Gas Phase Chemistry Files (. phs)

6 Gasact Example Gas Phase Plasma Chemistry (Argon) § Species: E, Ar*, Ar+ Reaction G 1 E + Ar -> E + Ar* G 2 E + Ar -> 2 E + Ar+ Reaction rate coefficient type Expression (from Boltzmann calc. ) Expression G 3 E + Ar* -> 2 E + Ar+ Expression G 4 Ar* + Ar* -> E + Ar+ Arrhenius G 5 E + Ar* Expression -> E + Ar G 6 Ar* + Ar -> Ar + Ar Arrhenius A 6. 2 e-16 B f(Te) Excitation Energy (ε) 11. 56 e. V f(Te) 16. 0 e. V f(Te) 4. 43 e. V 0. 0 C 0. 0 f(Te) 2. 5 e-21 0. 0 -11. 56 e. V 0. 0 § Expression indicates rate coefficient is fit as a function of temperature § Arrhenius rate coefficient is in the form k = A TB exp(-C/T) in units of molecules-meters-Kelvin

7 Gas Phase file overview Gas Phase Input File Walk-through (Ar_plasma_low. Pr_Bolsig_gas. phs) ## GASACT Gas-Phase Definitions Input File ## Low-pressure argon plasma ## Bolsig+ curve fit rates (Expr) ## Momemtum transfer cross section for AR* and AR# fn(E/N) for AR+ *PHASE GAS Mobility as a fn(Te) for E and Ar_plasma. Gas <species specification…> <thermodynamic specification…> <transport specification…> <reaction specification…> *ENDPHASE EOF § Four main parts: species, thermodynamic, transport, reaction

8 Gas species specification Gas Phase Input File Walk-through (Ar_plasma_low. Pr_Bolsig_gas. phs) ## GASACT Gas-Phase Definitions Input File ## Low-pressure argon plasma ## Bolsig+ curve fit rates (Expr) ## Momemtum transfer cross section for AR* and AR# fn(E/N) for AR+ *PHASE GAS Mobility as a fn(Te) for E and Ar_plasma. Gas ##----- Species specification *SPEC E AR+ AR* AR *ENDSPEC <rest of the file…> *ENDPHASE § Specify species to be used in the chemistry model within *SPEC …*ENDSPEC field § Each species in this list should have a corresponding definition in the species database file

Thermodynamics specification Gas Phase Input File Walk-through (Ar_plasma_low. Pr_Bolsig_gas. phs) *PHASE GAS Ar_plasma. Gas <species specification…> ##----- Species thermodynamics specifications *THERMOPTN POLYFIT <rest of the file…> *ENDPHASE § For plasmas simulated in Viz. Glow, specification of thermodynamics option is used in the case of equilibrium reactions (to calculate the equilibrium constant) § POLYFIT uses a NASA-style polynomial fit expression for thermodynamic properties (specified in species database file) § Alternative is PARTFUNC (uses partition function data to calculate thermodynamic properties) 9

10 Transport specification (1/3) Gas Phase Input File Walk-through (Ar_plasma_low. Pr_Bolsig_gas. phs) *PHASE GAS Ar_plasma. Gas <species and thermodynamic specification…> ##----- Species transport specifications *TRANSPORT_FORMULATION INDIVIDUAL *INDIVIDUAL_SPECIES_TRANSPORT_SPECIFICATION *DEFAULT_SPECIFIED_VARIABLE_FORMAT *DEFAULT_SPECIFIED_VARIABLE_CUSTOMDATA_NAME E MOBILITY_AND_DIFFUSION_COEFFICIENT_TIMES_N CUP mobility_times_n_bolsigplus diffusion_coeff_times_n_bolsigplus *END_INDIVIDUAL_SPECIES_TRANSPORT_SPECIFICATION <rest of the file…> *ENDPHASE MOMTR_CROSS_SECTION CUX momtr_crs

Transport specification (2/3) Gas Phase Input File Walk-through (Ar_plasma_low. Pr_Bolsig_gas. phs) *PHASE GAS T Ar_plasma. Gas <species and thermodynamic specification…> ##----- Species transport specifications *TRANSPORT_FORMULATION INDIVIDUAL <rest of the file…> *ENDPHASE § Transport formulation for solving Viz. Glow plasma problems should be set to INDIVIDUAL § Individual transport specification implies transport coefficients (cross section, collision frequency, mobility, diffusion coefficient, thermal conductivity) should be provided for each species in the plasma § Can simplify individual transport specification using a default that is true for most species, and over-riding the default only when it is necessary (most often for electrons) 11

12 Transport specification (3/3) Gas Phase Input File Walk-through (Ar_plasma_low. Pr_Bolsig_gas. phs) *PHASE GAS Ar_plasma. Gas <species, thermodynamic, and transport formulation specification…> *INDIVIDUAL_SPECIES_TRANSPORT_SPECIFICATION *DEFAULT_SPECIFIED_VARIABLE_FORMAT *DEFAULT_SPECIFIED_VARIABLE_CUSTOMDATA_NAME E MOMTR_CROSS_SECTION CUX momtr_crs MOBILITY_AND_DIFFUSION_COEFFICIENT_TIMES_N CUP mobility_times_n_bolsigplus diffusion_coeff_times_n_bolsigplus *END_INDIVIDUAL_SPECIES_TRANSPORT_SPECIFICATION <rest of the file…> *ENDPHASE § § Cross section is the default specified variable for most cases Electrons use separate specification for mobility and diffusion coefficient, will use data corresponding to the profiles (CUP) named “mobility_times_n_bolsigplus” and “diffusion_coeff_times_n_bolsigplus”

Reaction specification (1/3) Gas Phase Input File Walk-through (Ar_plasma_low. Pr_Bolsig_gas. phs) *PHASE GAS Ar_plasma. Gas <species, thermodynamic, and transport specification…> ##----- Gas chemical reactions specifications *RXNOPTN YES *RXNUNITSDEF MOLECULES-CM KELVINS *RXN AR + E -> AR* + E *PARAM 1. 1748 e-14 4. 6639 e-2 1. 3856 e 5 *RTEXPRF (TEMP>40614. 0)*EXP((-5. 8740934606*E(39)/(TEMP^8))+(5. 24737082175*E(35)/(TEMP^7))+(- 1. 93700150024*E(31)/(TEMP^6))+(3. 83610085957*E(26)/(TEMP^5))+(4. 44340804098*E(21)/(TEMP^4))+(3. 04020908509*E(16)/(TEMP^3))+(1. 21749700792*E(11)/(TEMP^2))+(1. 12162207523*E(5)/(TEMP^1))+(-3. 08536086905*E(1)/(TEMP^0))) *TDEP E *EXCI E 11. 56 *RTACTVF EXPR *RXNUNITS MOLECULES-M KELVINS *COMMENT Rate below 23208. 0 K is ~ 0 (< 1 e-28) *ENDCOMMENT *ENDRXN <rest of the reactions…> *ENDPHASE 13

Reaction specification (2/3) Gas Phase Input File Walk-through (Ar_plasma_low. Pr_Bolsig_gas. phs) *PHASE GAS Ar_plasma. Gas <species, thermodynamic, and transport specification…> ##----- Gas chemical reactions specifications *RXNOPTN YES *RXNUNITSDEF MOLECULES-CM KELVINS <reaction specifications…> *ENDPHASE § *RXNOPTN (Reaction option) should always be set to YES for Viz. Glow simulations § *RXNUNITSDEF (Default reaction units) will be used if units are not specified within the reaction specification 14

15 Reaction specification (3/3) Gas Phase Input File Walk-through (Ar_plasma_low. Pr_Bolsig_gas. phs) *RXN AR + E -> AR* + E *PARAM 1. 1748 e-14 4. 6639 e-2 1. 3856 e 5 *RTEXPRF (TEMP>40614. 0)*EXP((5. 8740934606*E(39)/(TEMP^8))+(5. 24737082175*E(35)/(TEMP^7))+(1. 93700150024*E(31)/(TEMP^6))+(3. 83610085957*E(26)/(TEMP^5))+(4. 44340804098*E(21)/(TEMP^4))+(3. 04020908509*E(16)/(TEMP^3))+(1. 21749700792*E(11)/(TEMP^2))+(1. 12162207523*E(5)/(TEMP^1))+(3. 08536086905*E(1)/(TEMP^0))) *TDEP E *EXCI E 11. 56 *RTACTVF EXPR *RXNUNITS MOLECULES-M KELVINS *COMMENT Rate below 23208. 0 K is ~ 0 (< 1 e-28) *ENDCOMMENT *ENDRXN § *RTACTVF (Forward rate coefficient formulation): EXPR is for expression, ARRH for Arrhenius-type reaction rate coefficient Reaction G 1 E + Ar -> E + Ar* Reaction rate coefficient type Expression (from Boltzmann calc. ) A B f(Te) C Excitation Energy (ε) 11. 56 e. V

16 Species Data Base Files (. dbs)

Species data file overview (1/2) Species Data Base File Walk-through (Ar_plasma_specdata. dbs) ## ## ## Species Database file for Gasact and Surfact Libraries This file contains properties for Argon plasma species AR AR* AR+ E AR 2 m AR 2+ (ARm) *SPECDATA AR *ELEMCOMP 1 AR 1 *PHASETYPE GAS *NASAPOLY *TRANGE 2 200. 0 1000. 0 5000. 0 (2. 5, 0. 0, 0. 0, -745. 375, 4. 366) *ENDNASAPOLY *PARTFUNC *GEOM MONOATOMIC *THETA_ROT 0. 0 *THETA_VIB 0. 0 *ECHEMREF 0. 0 *LEVELS (0. 0, 1) *ENDLEVELS *ENDPARTFUNC *TRANPARAM 0 136. 5 7. 136 0. 0 *ENDTRANPARAM *BEGIN_CUX_DATA *X_UNITS EV 40. 0 *END_CUX_DATA *ENDSPECDATA momtr_crs *VAL_UNITS A 2 <data for other species…> EOF *X_RANGE 0. 0 1000. 0 17

Species data specification overview (2/2) Species Data Base File Walk-through (Ar_plasma_specdata. dbs) *SPECDATA AR *ELEMCOMP 1 AR 1 *PHASETYPE GAS <species specification…> *NASAPOLY *TRANGE 2 200. 0 1000. 0 5000. 0 (2. 5, 0. 0, 0. 0, -745. 375, 4. 366) *ENDNASAPOLY *PARTFUNC *GEOM MONOATOMIC *THETA_ROT 0. 0 *THETA_VIB 0. 0 *ECHEMREF 0. 0 *LEVELS (0. 0, 1) *ENDLEVELS *ENDPARTFUNC <thermodynamic specification…> *TRANPARAM 0 136. 5 7. 136 *ENDTRANPARAM *BEGIN_CUX_DATA *X_UNITS EV 40. 0 *END_CUX_DATA 0. 0 momtr_crs *VAL_UNITS A 2 <transport specification…> *X_RANGE 0. 0 1000. 0 *ENDSPECDATA § Three main parts: species, thermodynamic, transport 18

19 Species data file overview (2/2) Species Data Base File Walk-through (Ar_plasma_specdata. dbs) *SPECDATA AR *ELEMCOMP 1 AR 1 *PHASETYPE GAS <composition specification…> *NASAPOLY *TRANGE 2 200. 0 1000. 0 5000. 0 (2. 5, 0. 0, 0. 0, -745. 375, 4. 366) *ENDNASAPOLY *PARTFUNC *GEOM MONOATOMIC *THETA_ROT 0. 0 *THETA_VIB 0. 0 *ECHEMREF 0. 0 *LEVELS (0. 0, 1) *ENDLEVELS *ENDPARTFUNC <thermodynamic specification…> *TRANPARAM 0 136. 5 7. 136 *ENDTRANPARAM *BEGIN_CUX_DATA *X_UNITS EV 40. 0 *END_CUX_DATA 0. 0 momtr_crs *VAL_UNITS A 2 <transport specification…> *X_RANGE 0. 0 1000. 0 *ENDSPECDATA § Three main parts: species composition, thermodynamic, transport

Species composition specification Species Data Base File Walk-through (Ar_plasma_specdata. dbs) *SPECDATA AR *ELEMCOMP 1 AR 1 *PHASETYPE GAS <remaining data…> *ENDSPECDATA *SPECDATA AR+ *ELEMCOMP 2 AR 1 E -1 *PHASETYPE GAS <remaining data…> *ENDSPECDATA § Species names can be user-defined, whereas element names are fixed (see Viz. Glow Software Manual, Table 5. 3 for list of element names) § *ELEMCOMP (Element composition) can have positive and negative numbers) § *PHASETYPE is GAS, SURFACE, or BULK (species of all 3 phase-types can be in the same file) 20

Species transport specification (1/2) Species Data Base File Walk-through (Ar_plasma_specdata. dbs) *SPECDATA AR <composition and thermodynamic data…> *TRANPARAM 0 136. 5 7. 136 0. 0 *ENDTRANPARAM *BEGIN_CUX_DATA momtr_crs *X_UNITS EV *VAL_UNITS A 2 *X_RANGE 0. 0 1000. 0 40. 0 *END_CUX_DATA <remaining data…> *ENDSPECDATA § § § *TRANPARAM is not used for INDIVIDUAL transport specification that was set in gas phase file The label “momtr_crs” for CUX data was defined as the default individual transport property, and should be included in the *SPECDATA field for each species Multiple CUX data or CUP data fields can be included for each species, and the desired one selected from the gas phase individual transport specification 21

Species transport specification (2/2) Species Data Base File Walk-through (Ar_plasma_specdata. dbs) *SPECDATA E <composition, thermodynamic, previous transport data…> *BEGIN_CUP_DATA mobility_times_n_bolsigplus *X_UNITS EV *VAL_UNITS 1/V-M-S *BEGIN_PROFILE (0. 02846756, 1. 289 e+26) (0. 02975487, 1. 33 e+26) (0. 03173586, 1. 383 e+26) (0. 03477738, 1. 448 e+26) (0. 03937968, 1. 523 e+26) (0. 04614973, 1. 604 e+26) … (67. 367, 4. 134 e+23) (85. 4427, 4. 026 e+23) (100. 0, 4. 026 e+23) *END_PROFILE *END_CUP_DATA <remaining data…> *ENDSPECDATA § § *X_UNITS is used to define whether the data is specified as a function of temperature or reduced electric field *VAL_UNITS is used to define whether the data is mobility/diffusion coefficient/collision frequency/cross section 22

How transport data in database file is selected from gas phase file Ar_plasma_low. Pr_Bolsig_gas. phs *PHASE GAS Ar_plasma. Gas … *INDIVIDUAL_SPECIES_TRANSPORT_SPECIFICATION *DEFAULT_SPECIFIED_VARIABLE MOMTR_CROSS_SECTION *DEFAULT_SPECIFIED_VARIABLE_FORMAT *DEFAULT_SPECIFIED_VARIABLE_CUSTOMDATA_NAME E MOBILITY_AND_DIFFUSION_COEFFICIENT_TIMES_N mobility_times_n_bolsigplus diffusion_coeff_times_n_bolsigplus *END_INDIVIDUAL_SPECIES_TRANSPORT_SPECIFICATION … *ENDPHASE Ar_plasma_specdata. dbs CUX momtr_crs *SPECDATA AR … *BEGIN_CUX_DATA momtr_crs *X_UNITS EV *VAL_UNITS A 2 … *END_CUP_DATA … *ENDSPECDATA CUP *SPECDATA E … *BEGIN_CUP_DATA mobility_times_n_bolsigplus *X_UNITS EV *VAL_UNITS 1/V-M-S … *END_CUP_DATA *BEGIN_CUP_DATA diffusion_coefficient_times_n_bolsigplus *X_UNITS EV *VAL_UNITS 1/M-S … *END_CUP_DATA … *ENDSPECDATA 23

24 Surfact Surface Chemistry Files (. phs)

25 Surfact Example Surface Plasma Chemistry (Argon) § Species: E, Ar*, Ar+ Reaction S 1 S 2 S 3 E -> Ar* -> Ar Ar+ -> Ar Sticking Coefficient 1. 0

Surface Phase file overview Surface Phase Input File Walk-through (Ar_plasma_low. Pr_surf. phs) ## ## SURFACT Surface Chemistry Input file Argon plasma on a simple quench surface ## The type of phase and the name of this phase *PHASE SURFACE quench. Surf <secondary electron emission specification…> <site and bulk density specification…> <thermodynamic specification…> <reaction specification…> *ENDPHASE EOF § Four main parts: secondary emission, site and bulk density specification, thermodynamic, reaction 26

Surface secondary emission specification Surface Phase Input File Walk-through (Ar_plasma_low. Pr_surf. phs) *PHASE SURFACE quench. Surf ## Secondary electron emission coefficient for gas species (CUX) *SECEEC AR+ 0. 008 *ENDSECEEC ## The energy of secondary electrons that are emitted from the surface ## (units: e. V) *SECENERGY 4. 0 <rest of the file…> *ENDPHASE § *SECEEC needs to be specified individually per species (default is zero, typically non-zero for ions and some metastables) § Secondary emission coefficient value is a CUX(TEMP, ENRG) § *SECENERGY is roughly the order of the surface material work function 27

Surface site and bulk density specification Surface Phase Input File Walk-through (Ar_plasma_low. Pr_surf. phs) *PHASE SURFACE quench. Surf <secondary electron emission specification…> ## The name of sites on the surface, the site density (units: moles/m 2) *SITE CUSURF 3. e-5 *ENDSITE ## The bulk species associated with this surface *BULK CUBULK *ENDBULK <rest of the file…> *ENDPHASE § There can be multiple *SITE keywords for a given surface, each needs to specify an area density § The *BULK keywords specifies densities of bulk species associated with a given surface 28

29 Surface reaction specification Surface Phase Input File Walk-through (Ar_plasma_low. Pr_surf. phs) *PHASE SURFACE quench. Surf <secondary electron emission, site and bulk density specification…> *RXNOPTN YES *RXNUNITSDEF MOLES-CM KELVINS ## Listing of all surface reactions *RXN E -> *PARAM 1. 0 0. 0 *STICK *RTEXPRF 1. 0*E(-4)*TEMP *RTACTVF ARRH *COMMENT Electron consumption at surface *ENDRXN *ENDCOMMENT <other reactions…> *ENDPHASE § Surface reactions that involve (one) gas phase species interacting with the surface are sticking-type reactions (*STICK) § Similar to gas phase reactions, *RTACTVF can be set as Arrhenius (ARRH) or expression (EXPR)

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