Introduction to the electron Boltzmann equation solver...

transcript

Introduction to the electron Boltzmann equation solver

BOLSIG+ (and the data platform LXCat)

Gerjan Hagelaar

Laboratoire Plasma et Conversion d’Énergie (LAPLACE), Université Paul Sabatier Bât 3R2, 118 route de Narbonne

31062 Toulouse Cedex 9, France gerjan.hagelaar@laplace.univ-tlse.fr

Introduction

In 2005 we released the freeware BOLSIG+ which since then has become a popular tool in low temperature plasma physics:

BOLSIG+ solves the electron Boltzmann equation for field equilibrium: homogeneous electric field E and gas density N, no boundaries, steady state

Input: complete sets of cross sections vs electron impact energy

Output: EEDF, swarm parameters, transport & rate coefficients vs E/N

G. J. M. Hagelaar and L. C. Pitchford, "Solving the Boltzmann equation to obtain electron transport coefficients and rate coefficients for fluid models", Plasma Sources Sci. Technol. 14 (2005) 722-733

Freeware downloadable from www.bolsig.laplace.univ-tsle.fr

Different purposes of BOLSIG+

Checking cross sections against swarm data

• Mean velocity

• Anisotropic diffusion coefficients DL & DT

• Townsend coefficient

• vs E/N

• Definitions consistent with measured quantities

• Accuracy

• Validity of 2-term velocity expansion?

Generating data for fluid discharge modeling

• Mobility

• Mean energy

• Rate coefficients

• Energy loss coefficients

• vs E/N or mean energy

• Definitions consistent with coefficients in fluid equations

• Computational speed

• Gradients, boundaries, nonlocal effects: is BOLSIG+ applicable?

Purpose:

Results of primary interest:

Issues:

Basic equations

Boltzmann equation:

1constant

0 1( , , ) ( , ) ( ) ( )cosf t n t F F r v r

221/20

0 0 0[ ,{ ( )}]

dFe E dC F F

N d Q d N

m 1/2( )Q

f ef f NC f

collision operator acceleration

2-term approximation:

isotropic part (EEDF)

anisotropic part (transport)

1/2(2 / )m

2( / )v

momentum cross section:

substituting

electron density

PT growth model: 1

constantn

altneratively: (SST) creation rate

reduced electric field full set of cross sections

4 Many additional options: AC field, gas mixtures, e-e collisions…

Swarm parameters & fluid coefficients

010 03 3

dFe Ew F d d

00k F d

Mean energy

Mean velocity

Mobility

Diffusion coefficient

Rate coefficients

Townsend coefficients

dFeN d

003TD N F d

(for each collision process)

Running BOLSIG+ (1)

Running BOLSIG+ (2)

Running BOLSIG+ (3)

Running BOLSIG+ (4)

e-e Coulomb collisions Maxwellize the EEDF

G. J. M. Hagelaar and L. C. Pitchford, Plasma Sources Sci. Technol. 14 (2005) 722-733

electron energy probability function (EEPF): Maxwellian = straight line on semilog plot

without e-e collisions with e-e collisions for different n/N

without e-e

EEDF is different in oscillating field

G. J. M. Hagelaar and L. C. Pitchford, Plasma Sources Sci. Technol. 14 (2005) 722-733

DC field AC field with different /N

DC field

Anisotropic diffusion theory

BOLSIG+ has recently been extended to calculate separate longitudinal and transverse diffusion coefficients DL and DT using a density gradient expansion [1,2]:

1 ( , ) 1 ( , )

( , , ) ( ) ( , ) ( ) ( )n t n t

f t F n t G HN z N r

r rr v v r v v

0 1( ) ( ) ( )cosG G G v

D N F dQ

3 3L T

dGED N D N d w Fd

N Q d Q

2 2 1/21/2 1/20 0 0

0 0 0 0 02

1[ ] 2

dG dF dFE d E d E dC G G w F f

N d Q d N N d d N Q d d QQ

0 1( ) ( ) ( )cosH H H v

[1] J. H. Parker and J. J. Lowke, Phys. Rev. 181, 290 (1969) [2] Phelps and Pitchford, Phys. Rev. A 25, 540 (1982)

1 0H F

One can show that:

G0 solved from additional equation, similar to F0 equation:

1/2 1/2

0 00 00G d H d

Anisotropic diffusion coefficients DL & DT

Diffusion coefficient in previous BOLSIG+ versions corresponds to DT

Main interest of DL and DT: analysis of swarm data vs cross section data

Limited interest for fluid models: plasma diffusion (against ambipolar field) essentially different from BOLSIG+, Einstein relation as good or better

E/N (Td)

Diffusion coefficient in N2

DL Einstein

Einstein exact at E/N =0

Einstein relation:

BOLSIG+ input data: LXCat database

Input cross section data from by many contributors can be downloaded from LXCat website www.lxcat.net

BOLSIG+ requires complete sets of cross sections: elastic momentum transfer + total inelastics + ionization

LXCat includes online simplified version of BOLSIG+

Input data example: Argon cross section sets on LXCat

L. C. Pitchford et al, J. Phys. D 46 (2013) 334001 15

Gas temperature effects at low E/N

For E/N→0 the electron distribution function becomes Maxwellian at gas temperature

To obtain this with BOLSIG+ in molecular gases, it is necessary to include superelastic inverse processes for all low-threshold excitations, with equilibrium upper level populations

Characteristic energy in H2:

300 K = 0.026 eV

We currently are considering how to simplify/automatize the inclusion of collisions with ro-vibrational states, using analytical approximations L. C. Pitchford et al, poster at GEC 2012, Austin 16

How good is 2-term? Generally very good!

BOLSIG+ results have been compared with Monte Carlo simulations [1,2] for many gases and conditions

Generally excellent agreement (within 10% for all results) provided that cross-sections and system described are exactly the same

Even at high E/N, differences between BOLSIG+ and MC do not exceed differences due to assumptions on growth (PT/SST), inelastic angular scattering, energy sharing, etc

Dramatic failure of 2-term approximation claimed by some authors is most likely a misinterpretation of effects of inconsistent cross-sections, conditions, or parameter definitions

[1] G. J. M. Hagelaar, MCIG, Monte-Carlo version of BOLSIG+ (unpublished, 2012)

[2] S. F. Biagi, Nucl. Instr. and Meth. A 421, 234 (1999)

Example 1: BOLSIG+ vs MC vs experiments in N2

L. C. Pitchford et al, poster at GEC 2012, Austin

Mobility Townsend coefficient

Comparisons BOLSIG+ vs Monte Carlo (Biagi) vs experimental swarm data for different set of N2 cross sections: BOLSIG+ agrees well with other data

Example 2: High E/N in Ar

Without electron creation, runaway set in > 1000 Td

100 1000

no growth

BOLSIG+

MC isotropic

MC forward

E/N (Td)

100 10000

no growth

BOLSIG+

MC isotropic

MC forward

E/N (Td)

Failure of SST for E/N > 700 Td in BOLSIG+ but not in MC

Comparisons BOLSIG+ vs MCIG for different growth models and different assumptions on angular scattering in inelastic collisions: good agreement

Cross sections from Siglo database, www.lxcat.net, retrieved 26/09/2013 19

Example 3: Diffusion in CF4 (notoriously problematic)

10 100 100010

Einstein

BOLSIG+

E/N (Td)

Cross sections from Hayashi data base, www.lxcat.net, retrieved 29/09/2013

Energy (eV)

Q(elastic) << Q(inelastic)

Comparisons of anisotropic diffusion coefficients in CF4 calculated with BOLSIG+ vs MCIG: failure of 2-term density-gradient expansion

Note: Other parameters (, , , k, etc) OK

Known exceptions where BOLSIG+ fails

In some gases: large errors in diffusion coefficients while other parameters OK, due to failure of 2-term density-gradient expansion:

DT in Ramsaurer gases (Ar, Kr, Xe)

DL and DT in some molecular gases (CF4) with Q(inelastic) >> Q(elastic) at low energy

Failure of SST (steady-state Townsend) growth model at high E/N, probably related to 2-term approximation

Failure of PT/SST growth models for high electron attachment rate, when attachment frequency >> inverse energy relaxation time, observed also in MC calculations so unrelated with 2-term

How good is BOLSIG+ for real plasmas? Depends…

Unlike BOLSIG+, real discharge systems involve boundaries and field variations/reversals/transients which affect the electron kinetics, sometimes severely

BOLSIG+ like ( field equilibruim)

• Swarm experiment • Townsend discharge • DC positive column • Microwave discharge

Essentially different (no local field equibrium)

• Spatial/temporal afterglow • Negative glow • Hollow cathode discharge

Use of BOLSIG+ data for discharges is a practical generalization, often better than assuming a Maxwellian EEDF, but not to be taken literally

Use of BOLSIG+ data vs mean energy (local mean energy approximation) is nothing more than a useful patch between field-equilibrium theory and classical fluid dynamics it cannot describe nonlocal electron kinetics!

Examples:

Appendix

Presentation on LXCat at the Gaseous Electronics Conference 2-7 November 2014, Raleigh NC, USA

by Leanne Pitchford

LXCat : a web-based, community-wide project on data needed in modeling

low temperature plasmas

Presented by Leanne Pitchford, on behalf of the LXCat team

LAPLACE, Univ Toulouse and CNRS Toulouse, France

www.lxcat.net

LXCat = ELECtron (and ion) SCATtering

Data needs in the field of low temperature plasma science (LTPS) are extensive

Electron-neutral (cross sections and/or transport coefs) Ion-neutral (cross sections and/or transport coefs) Neutral and ion chemistry Plasma surface interactions Radiation ….

Present focus of the LXCat project (electron component): scattering cross sections from ground state targets, over an energy range from thermal to some kV.

The starting point for the LXCat project (2008)

Some on-line compilations of data were available in various formats, more or less complete, accurate – examples : Phelps, Morgan, SIGLO Extensive cross section data sets were available, hard-wired in Fortran codes – example : SF Biagi’s Magbotz code (35000 lines of Fortran code) contains data for over 40 target species. Compilations of cross section data have been published – examples : Itikawa, Hayashi,.. People are generally willing to share data. Many data are available for cross sections for particular processes, transport coefficients in particular gas mixtures….mainly in figure format.

- The DOE report of the workshop on Low Temperature Plasmas (March 2008) stated as a priority to “Establish a clearinghouse for fundamental data for LTPS. A hierarchical evaluation, ranging from rough approximations to accurate and complete datasets, should be created. The data should be brought together, evaluated by experts, and made widely available by using up-to-date Web-based techniques.” - Independently of this assessment, the group in Toulouse (mainly Sergey Pancheshnyi) developed an open access website, into which data can be

uploaded. On-line tools were developed for manipulating data.

Conclusions from the public discussion at GEC 2010 - there is considerable interest/need in the GEC community for developing modern

databases and on-line tools for LTPST - a community-wide effort is desirable with a well-identified structure to assure survivability (continuity + good technical solutions to avoid dead-ends) - a number of people are ready to support this effort - many questions need to be addressed ..scope, evaluation, organization, IP,.., overlap with other projects,… - the Toulouse platform is a good starting point

GEC Plasma Data Exchange Project

The Gaseous Electronics Conference agreed to host three workshops focusing on data for modeling LTP’s. 2011 : organization of a workshop at the GEC, poster contributions on noble gases 2012 : organization of a workshop at the GEC, poster contributions on simple molecular gases 2013: organization of a workshop at the GEC, poster contributions on H2O

Most of the data presented in the workshops are now available on LXCat and intercomparisons have been presented in poster sessions at previous GEC’s.

LXCat in 2014

On-line tools

www.lxcat.net

Contributors

Individual databases ~20 at present

(~ 30 people from 12 countries)

S. Pancheshnyi et al., Chem. Phys. 398, 148 (2012)

Contributors to The LXCat project (updated November 2014)

Website conception and development: S Pancheshnyi, France /Switzerland

Electrons: Compilations of cross section data : MC Bordage, V. Puech, LC Pitchford, France; SF

Biagi, UK; WL Morgan, AV Phelps USA; LL Alves and CM Ferreira, Portugal; Kochetov and Napartovich, Russia; Y. Itikawa, (M Hayashi), Japan; L Campbell and M Brunger, Australia + Chris Brion’s library of optical oscillator strengths, Canada

Quantum calculations: J. Tennyson and D. Brown, UK; O. Zatsarinny and K. Bartschat USA; I. Bray

and D. Furst, Australia; Al Stauffer, Canada

Compilations of experimental transport coefficients: transcription of data from publications

S. Chowdhury, France/India; J. de Urquijo, Mexico; LL Alves, Portugal

Ions: L Viehland, AV Phelps, USA; J. de Urquijo, Mexico

On-line Boltzmann solver for electrons: GJM Hagelaar, France

Technical assistance: S. Chowdhury and B Chaudhury, France/India;

Mirror site : J van Dyke, the Netherlands

Data needs depend on the model formulation

Complete sets of cross sections: electron-neutral (ground state) describing momentum-loss, energy-loss processes, and electron number changing processes (ionization, attachment, …)

Boltzmann solver Cross

sections

parameters

Swarm parameters: electron transport (mobiity, diffusion), rate coefficients as functions of E/N (if non-Maxwellian) or average energy

Consistency of measured and calculated swarm parameters is a minimum requirement for validation of the cross section data set.

For the electron component, the emphasis in LXCat is on the cross section data, from which swarm parameters can be derived.

How to find LXCat

e.g. mobility

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FAST"NAVIGATION

PROJECT"STATISTICS

Scattering cross sections: 19 databases | 4 x 162

species | 3.2k records | updated: 25 August 2014

Differential scattering cross sections: 1 database | 1

species | 31 records | updated: 7 November 2013

Interaction potentials: 1 database | 56 x 8 species |

567 records | updated: 23 September 2014

Oscillator strengths: 1 database | 65 species | 150

records | updated: 25 November 2013

Swarm / transport data: 8 databases | 264 x 60

species | 129.8k records | updated: 23 September 2014

Publications, notes and reports: 3 databases | 23

records | updated: 25 August 2013

about the project » news and events » statistics and geography » the lxcat team

About the project

The Plasma Data Exchange Project is a community-based project which was initiated as a result of a public discussion

held at the 2010 Gaseous Electronics Conference (GEC), a leading international meeting for the Low-Temperature

Plasma community. This project aims to address, at least in part, the well-recognized needs for the community to organize

the means of collecting, evaluating and sharing data both for modeling and for interpretation of experiments.

At the heart of the Plasma Data Exchange Project is LXcat (pronounced "elecscat"), an open-access website for

collecting, displaying, and downloading electron and ion scattering cross sections, swarm parameters (mobility, diffusion

coefficient, etc.), reaction rates, energy distribution functions, etc. and other data required for modeling low temperature

plasmas. The available data bases have been contributed by members of the community and are indicated by the

contributor's chosen title.

This is a dynamic website, evolving as contributors add or upgrade data. Check back again frequently.

Suppor ting organizations

HOMEHOME HOW TO USEHOW TO USE CONTRIBUTORSCONTRIBUTORS DATA CENTERDATA CENTER ONLINE CALCULATIONSONLINE CALCULATIONS DOCS AND LINKSDOCS AND LINKS DISCUSSION BOARDDISCUSSION BOARD

e . g . m o b i l i ty

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S C A T T E R I N G " C R O S S " S E C T I O N S

D I F F E R E N T I A L " S C A T T E R I N G " C R O S S " S E C T I O N S

I N T E R A C T I O N " P O T E N T I A L S

O S C I L L A T O R " S T R E N G T H S

S W A R M " / " T R A N S P O R T " D A T A

G L O B A L " S P E C I E S " F I L T E R I N G

E L E C T R O N S

I O N S

C o p yri g h t © 2 0 0 9 -2 0 1 3 , t h e L XC a t t e a m . T h e u se w i t h o u t p ro p e r re f e re n ci n g t o d a t a b a se s a n d so f t w a re u se d i s p ro h i b i t e d . Al l R i g h t s R e se rve d .

d a ta ty p e » d a t a b a se s » ?rst sp e ci e s » se co n d sp e ci e s » d a t a g ro u p s » p ro ce sse s » output

HO M E HO M E HO W T O U SE HO W T O U SE C O N TR IB U T O R S C O N TR IB U T O R S D A T A C EN TER D A T A C EN TER O N L IN E C A L C U L A TIO N S O N L IN E C A L C U L A TIO N S D O C S A N D L IN K S D O C S A N D L IN K S D IS C U S S IO N B O A R D D IS C U S S IO N B O A R D

b r ow s e a n d d ow n l oa d b r ow s e a n d d ow n l oa d

d ow n l oa d f or of f l i n e u s e d ow n l oa d f or of f l i n e u s e

a c c e s s t o p r e vi ou s v e r s i on s a c c e s s t o p r e vi ou s v e r s i on s

e.g. mobility

19 databases | 4 x 162 species | 3.2k records | updated: 25 August 2014

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SCATTERING"CROSS"SECTIONS

DIFFERENTIAL"SCATTERING"CROSS"SECTIONS

INTERACTION"POTENTIALS

OSCILLATOR"STRENGTHS

SWARM"/"TRANSPORT"DATA

GLOBAL"SPECIES"FILTERING

ELECTRONS

data type » databases » first species » second species » data groups » processes » output

Databases containing complete sets of cross sections for electron scatter ingfrom ground state neutral atoms and molecules.

The energy range of interest is from 0 to some 100's of eV and higher. A complete set of cross sections consists of

elastic momentum transfer, and total cross sections for the processes of ionization, attachment and excitation.

Complete sets of cross sections are needed as input to a Boltzmann equation solver to determine the electron or ion

energy distribution function.

Databases containing par tial sets of electron-neutral scatter ing crosssections.

Partial sets of electron neutral scattering cross sections are also included on this site. These include additional data

concerning electron collisions with ground state molecules - such as total scattering, total elastic scattering - not used

in the Boltzmann calculations. These also include cross sections for electron impact ionization of metastable or

radicals, needed for the calculation of stepwise ionization, for example.

Databases containing ion-neutral scatter ing cross sections.

The limited ion-neutral cross section data available on this site were derived assuming that the differential scattering

can be reasonably well approximated as the sum of an isotropic part and a backscatter part. These two components

are provided as functions of the center or mass energy.

e.g. mobility

no fi lter

SI GLO database

DESCRIPTION: The SIGLO database is the "in-house" data used by the group GREPHE at LAPLACE in Toulouse.

The data are taken from different sources as indicated for each gas. Please refer to original sources in publications.

An early version of this data file, "siglo.sec", was distributed with BOLSIG. The main changes in the present version

The format has been changed to be compatible with BOLSIG+.

Scale factors have been incorporated in the data and no longer appear explicitly.

He : The present data are from the compilation of A.V. Phelps (see reference in the Phelps data base).

O2 : We recommend using the data in the Phelps database for this species.

H2 : We recommend using the data in the Phelps database for this species.

Cl2 : The present data are an updated compilation (Jan 2012) by J Gregorio and LC Pitchford.

Cu : Feb 2012. Digitized from Tkachev A N, Fedenev A A and Yakovlenko S I, Laser Phys. vol.17, p. 775 (2007)

Kr : Nov 2012. We re-digitized the data from figs. 1 and 5 in H. Date, Y. Sakai and H. Tagashira, J. Phys. D 22 1478

(1989). With respect to the previous data from this same reference in the SIGLO database, there are some changes in

the threshold values and in the magnitudes of the inelastic cross sections.

CONTACT: LC Pitchford and JP Boeuf

pitchford@@laplace.univ-tlse.fr and jpb@@laplace.univ-tlse.fr

SCATTERING CROSS SECTIONS

e.g. mobility

no fi lter

Ground states

State-specific and gas mixtures

Ground states

State-specific and gas mixtures

e.g. mobility

Effec%ve Elas%c Excita%on Ioniza%on

«2PREV NEXT2»

no fi lter

STEP25:2SELECT2DATA2GROUPS2&2CLICK2NEXT

SELECT2ALL2&2FILTER2TOOL

Cross section

e.g. mobility

no fi lter

M organ (Kinema Research & Software)

e / Ar

SI GLO database

Data Group [Ar ] : From compilation of A.V. Phelps.

e / Ar

Phelps database

Data Group [Ar ] : Yamabe, Buckman, and Phelps, Phys. Rev. 27, 1345 (1983) . Revised Oct 1997.

e / Ar

Morgan (Kinema Research & Software)

SIGLO database

Biagi-v8.9 (Magboltz version 8.9)

e.g. mobility

USERS%MUST%AGREE%TO%THE%TERMS%OF%USE%TOACCESS%DATA%(BROWSE%AND%DOWNLOAD)

YES,%I%have%read%and%understood%»Terms of use

Users acknowledge understanding that LXCAT is a community-based project with open-access databases being freely

provided by individual contributors.

Proper referencing of mater ial retr ieved from this site is essential for thesurvival of the project.

Users further accept that the databases on this site remain property of their respective contributors and are not to be

distributed by third parties or used for commercial purposes. All questions regarding copyright should be addressed to

the LXCAT team.

H ow to reference data

Use of the data from this site in publications should be accompanied by proper references. Original references should be

used where possible and reference should be made to the specific database(s) from which data were retrieved, the LXCat

site address, and the retrieved date. Example:

Biagi-v8.9 database, www.lxcat.net, retrieved on September 28, 2014.

H ow to reference on-line calculations

Swarm coefficient calculated on this site should make reference to both the cross section data in the above format and to

BOLSIG+, the Boltzmann solver used in the calculations:

G.J.M. Hagelaar and L.C. Pitchford, "Solving the Boltzmann equation to obtain electron transport coefficients and

rate coefficients for fluid models", Plasma Sci Sources and Tech 14, 722 (2005).

H ow to reference text documents

Publications and conference proceedings should be referenced according to journal specifications. All unpublished

material on this site should be referenced as "private communication" with the date given on the document, the author's

name, date, and the retrieved date. Example:

Morgan database, private communication, www.lxcat.net, retrieved on September 28, 2014.

Terms of use

How to reference data

How to reference on-line calculations

How to reference text documents

Proper referencing of material retrieved from this site is essential for the

survival of the project.

Time machine tool

Put in place on Nov 12, 2013. All changes in the databases since that time are recorded and data can be recovered as they existed on any day since then.

Important for referencing!!

e.g. mobility

no fi lter

M organ (Kinema Research & Software)

e / Ar

SI GLO database

Data Group [Ar ] : From compilation of A.V. Phelps.

e / Ar

Phelps database

Data Group [Ar ] : Yamabe, Buckman, and Phelps, Phys. Rev. 27, 1345 (1983) . Revised Oct 1997.

e / Ar

Morgan (Kinema Research & Software)

SIGLO database

Biagi-v8.9 (Magboltz version 8.9)

e.g. mobility

DOWNLOAD'DATADOWNLOAD'IMAGERESCALE'IN'NEW'WINDOWKEEP'WINDOW'AND'GO'BACKGO'BACK

Cross section

SI GLO databaseData Group [Ar ]e / Ar1.

e.g. mobility

DOWNLOAD'DATADOWNLOAD'IMAGERESCALE'IN'NEW'WINDOWKEEP'WINDOW'AND'GO'BACKGO'BACK

Cross section

SI GLO databaseData Group [Ar ]e / Ar1.

Download TXT, Download PNG, Browse, Re-scale

Linear scale, energy

Acsii text file for off-line use

file header

Data tables

BOLSIG+

Select components of gas mixture

Indicates that some documentation is available on-line

A full version of BOLSIG+ with many more options (e-e collisions, high frequency excitation, ExB,..) is available as freeware.

Results available on-line and by download

Create a temporary LXCat database containing these results

Temporary database containing results from on-line calculations

Compare measured and calculated swarm data

Compare measured and calculated swarm parameters

Gas mixture in temporary database

GEC Plasma Data Exchange Project => evaluation Cluster issue : 2013 J. Phys. D: Appl. Phys. 46 Issue 33 Paper I: Comparisons of sets of electron-neutral scattering cross sections and swarm parameters in noble gases I. Argon LC Pitchford, Alves LL, Bartschat K, Biagi SF, Bordage MC, Phelps AV, Ferreira CM, Hagelaar GJM, Morgan WL, Pancheshnyi S, Puech V, Stauffer A and Zatsarinny O Paper II: Comparisons of sets of electron-neutral scattering cross sections and swarm parameters in noble gases II. Helium and Neon LL Alves, Bordage MC, Biagi SF, Pitchford LC, Zatsarinny O, Bartschat K, Hagelaar GJM, Pancheshnyi S, Ferreira CM, Puech V, Morgan WL and Phelps AV Paper III: Comparisons of sets of electron-neutral scattering cross sections and swarm parameters in noble gases III. Krypton and Xenon MC Bordage, SF Biagi, LC Pitchford, K Bartschat, S Chowdhury, GJM Hagelaar, WL Morgan, V Puech, O Zatsarinny

Paper IV: Computational Methods for Electron-Atom Collisions in Plasma Applications K. Bartschat

LXCAT: some statistics

Where are they from?

An average of unique visitors per day

Future directions

• Continuing the enlargement of the databases, on-line tools

new contributors, new data types

• Giving contributors proper recognition for their work

consistent format for referencing among editors

• Continuing effort on evaluation of data some evaluations have been published, others have been presented at the GEC and will be published, & work is in progress for other molecules

• Structure, funding, connection to other sites (e.g. VAMDC)

To contribute, please contact lxcat.info@gmail.com

Introduction to the electron Boltzmann equation solver...

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