E LEMENTARY P ROCESSES, T HERMODYNAMICS AND T RANSPORT OF H 2, O 2 AND N 2 P LASMAS

COLLABORATORs

a) photodissociation of H 2 ( ), D 2 ( ), HD( ) and H 2 + ( ) b) heavy particle collision cross sections : H 2 ( ), D 2 ( ) from recombination c) H 2 ( ) formation on graphite d) heavy particle collision cross sections for O-O 2 and N-N 2 : fitting relations d) collision integrals for O-O and O-O + interactions e) collision integrals for N-N and N-N + interactions: a phenomenological approach a) thermodynamic properties of atomic hydrogen plasma b) transport properties of atomic hydrogen plasma: cut-off criteria c) negative ion source modeling OUTLINE

PHOTODISSOCIATION PROCESSES for H 2 ( ), D 2 ( ), HD( ) and H 2 + ( ) LYMAN and WERNER SYSTEMS HIGH-ENERGY EXTRAPOLATION for STATE-DEPENDENT CROSS SECTIONS derivation of STATE-DEPENDENT PHOTODISSOCIATION RATE COEFFICIENTS MACROSCOPIC PHOTODISSOCIATION RATE COEFFICIENT ( k tot ) FITTING FORMULAS

D.R.G. Schleicher et al. Astronomy&Astrophysics 490 (2008) 521 MACROSCOPIC PHOTODISSOCIATION RATE COEFFICINTS for H 2 ( ) and H 2 + ( ) : COMPARISON with LITERATURE H 2 ( ) LYMAN H 2 ( ) WERNER H 2 + ( )

HEAVY PARTICLE COLLISIONS VIBRATIONALLY EXCITED MOLECULES FROM RECOMBINATION QCT SIMULATION RECOMBINATION RATE COEFFICIENTs from QCT DISSOCIATION by DETAILED BALANCE THREE-BODY RECOMBINATION from RBC (Roberts, Bernstein & Curtiss) THEORY TWO-STEP BINARY COLLISION rotational barrier quasi-bound state

T = 1,000 KT = 300 K H 2 ( ) FROM RECOMBINATION

O 2 ( ), N 2 ( ) FROM RECOMBINATION O2O2 N2N2

ATOMIC RECOMBINATION on GRAPHITE SURFACE H 2 (, j) NASCENT DISTRIBUTIONs SEMI-CLASSICAL MODEL ELEY-RIDEAL MECHANISM (H CHEMISORBED at the SURFACE with a chemisorption well of 0.52eV ) PROBABILITIES dependence on SURFACE TEMPERATURE IMPACT ENERGY ISOTOPES SURFACE TEMPERATURE=500 K ENERGY = 0.07 eV M.RUTIGLIANO, M.CACCIATORE, CHEM.PHYS.CHEM. 9 (2008) 171 vibrational distribution is obtained summing up population of rotational levels

HEAVY PARTICLE COLLISION CROSS SECTIONS for O-O 2 and N-N 2 SYSTEMS FITTING RELATIONS ACCURATE QCT CROSS SECTIONS for VIBRATIONAL DEACTIVATION VT processes DISSOCIATION F.ESPOSITO, I.ARMENISE, G.CAPITTA, M.CAPITELLI, CHEM.PHYS 351 (2008) 91 fitting bidimensional relations EASY INCLUSION in KINETIC MODEL TEMPERATURE RATE COEFFICIENT [cm 3 s -1 ] TEMPERATURE RATE COEFFICIENT [cm 3 s -1 ] i =30 i =40 i =46 i =

COLLISION INTEGRALS for O-O and O-O + INTERACTIONS involving LOW-LYING EXCITED STATES SCHEME OF CLASSICAL APPROACH

A.LARICCHIUTA, D.BRUNO, M.CAPITELLI, R.CELIBERTO, C.GORSE, G.PINTUS, CHEM.PHYS.LETT. 344 (2008) 13 EFFECTIVE DIFFUSION-TYPE COLLISION INTEGRALS for O-O + INTERACTIONS involving LOW-LYING EXCITED STATES ELASTIC CONTRIBUTION from POTENTIALS and INELASTIC CONTRIBUTION from CHARGE-EXCHANGE CROSS-SECTIONS

A PHENOMENOLOGICAL MODEL for HEAVY PARTICLE COLLISION INTEGRALS CLASSICAL COLLISION INTEGRALS INTERACTION POTENTIAL PHENOMENOLOGICAL APPROACH AVERAGE INTERACTION fitting formulas up to (4,4) order A. LARICCHIUTA, G.COLONNA et al. Chemical Physics Letters 445 (2007) 133 “tuplet” ( ) characterising the colliding system

PHENOMENOLOGICAL APPROACH ION-NEUTRAL 4 6 INTERACTION POTENTIAL FEATURES correlation formulas from physical properties of colliding partners POLARIZABILITY, CHARGE and NUMBER of ELECTRONS EFFECTIVE in POLARIZATION F.PIRANI et al. International Review in Physical Chemistry 25 (2006) 165 NEUTRAL-NEUTRAL PREDICTION of POTENTIAL PARAMETER for UNKNOWN SYSTEMS hard interactionssoft interactions

COLLISION INTEGRALS COMPARISON between CLASSICAL and PHENOMENOLOGICAL APPROACHES LARICCHIUTA et al. (2008) CAPITELLI et al. (1972) phenomenological approach

INELASTIC (CHARGE TRANSFER) DIFFUSION-TYPE COLLISION INTEGRALs for N*-N + INTERACTIONs involving HIGH-LYING EXCITED STATES Dependence of diffusion-type collision integrals for the interaction N + ( 3 P)-N on the principal quantum number of the atom valence shell electrons, n, at T=10,000 K (different electronic states of N, arising from the same electronic configuration have been considered. n=2 N(2p 3 4 S, 2 D, 2 P), n=3 N(2p 2 3s 2 P, 4 P;), n=4 N(2p 2 4s 2 P, 4 P;), n=5 N(2p 2 5s 2 P, 4 P;)

EFFECTIVE DIFFUSION-TYPE COLLISION INTEGRALS for N-N + INTERACTIONS involving LOW-LYING EXCITED STATES ELASTIC CONTRIBUTION from PHENOMENOLOGICAL POTENTIALS and INELASTIC CONTRIBUTION from CHARGE-EXCHANGE CROSS-SECTIONS T = 10,000 K

a) photodissociation of H 2 ( ), D 2 ( ), HD( ) and H 2 + ( ) b) heavy particle collision cross sections : H 2 ( ), D 2 ( ) from recombination c) H 2 ( ) formation on graphite d) heavy particle collision cross sections for O-O 2 and N-N 2 : fitting relations d) collision integrals for O-O and O-O + interactions e) collision integrals for N-N and N-N + interactions: a phenomenological approach a) thermodynamic properties of atomic hydrogen plasma b) transport properties of atomic hydrogen plasma: cut-off criteria c) negative ion source modeling OUTLINE

THERMODYNAMIC PROPERTIES for ATOMIC HYDROGEN PLASMA M. Capitelli, D. Giordano, G. Colonna The role of Debye-Hückel electronic energy levels on the thermodynamic properties of hydrogen plasmas including isentropic coefficients Physics of Plasmas 15(8) (2008)

Internal partition functionInternal specific heat

internal state contribution reaction contribution CONTRIBUTION TO SPECIFIC HEAT Frozen Specific Heat Reactive Specific Heat

HYDROGEN MIXTURE ISENTROPIC COEFFICIENT Total Frozen

GROUND STATE METHODS DEBYE HÜCKEL CRITERION CONFINED ATOM APPROXIMATION internal energy = 0 particle density IN ANY CASE DRASTICALLY DECREASES INCREASING PRESSURE or ELECTRON DENSITY!!! TRANSPORT PROPERTIES for ATOMIC HYDROGEN PLASMA : CUT-OFF CRITERIA

EFFECT of DIFFERENT CUT-OFF CRITERIA on ATOMIC HYDROGEN NUMBER DENSITY GROUND-STATE DEBYE-HUCKEL CONFINED-ATOM Trampedach et al. Astrophys. J. (2006)

DIFFUSION-TYPE COLLISION INTEGRALS VISCOSITY-TYPE COLLISION INTEGRALS COLLISION INTEGRALs for H(n)-H + INTERACTIONs compared with COULOMB COLLISION INTEGRALs

case USUALEES considered as independent chemical species BUT EES collision integrals set equal to ground state ones case ABNORMALEES considered as independent chemical species with their own collision integrals

EFFECT of DIFFERENT CUT-OFF CRITERIA on TRANSPORT PROPERTIES of HYDROGEN PLASMA including ABNORMAL TRANSPORT CROSS SECTIONs for EES HEAVY PARTICLE THERMAL CONDUCTIVITYVISCOSITY GROUND-STATE DEBYE-HUCKEL CONFINED-ATOM D. Bruno, M. Capitelli, C. Catalfamo, A. Laricchiuta Physics of Plasmas (2008) in press

EFFECT of DIFFERENT CUT-OFF CRITERIA on TRANSPORT PROPERTIES of HYDROGEN PLASMA including ABNORMAL TRANSPORT CROSS SECTIONs for EES GROUND-STATE DEBYE-HUCKEL CONFINED-ATOM REACTIVE THERMAL CONDUCTIVITYINTERNAL THERMAL CONDUCTIVITY

3 CRITICAL AREAS (“remote” source) Source chamber (driver): ICP (transformer) heating at high RF power No sheath losses Hot electrons Expansion region: H 2 vibrational excitation Extraction region: Magnetic filtering Cold electrons H - production (surface/volume) Electron removal Length0.35 m Radius0.2 cm Input Power170 kW Current coil100 A Frequency1 MHz Pressure0.6 Pa Max magnetic field160 G Extraction grid potential-20 kV RF-ICP NEGATIVE ION SOURCE

Boltzmann T g VDF H 2 (v) vibrational distribution function (*) J. R. Hiskes et al., J. Appl. Phys. 53(5), 3469 (1982) (**) O. Fukumasa, K. Mutou, H. Naitou, Rev. Sci. Instrum. 63(4), 2693 (1992) EXPANSION REGION: H 2 ( ) EXCITATION H 2 ( ) VIBRATIONAL DISTRIBUTION FUNCTION

(cm) (a) U. Fantz, et al., Plasma Phys. Control. Fus. 49(12B), (2007). PGPLASMA GRID TO THE DRIVER DRIVER EXIT EXTRACTION REGION EXPANSION REGION transition from a classical sheath drop to a complete reversed sheath EXTRACTION REGION RESULTS: PG BIAS EFFECT

FUTURE PERSPECTIVEs a) elementary gas-phase processes involving Caesium b) direct approaches for gas-phase recombination c) H 2 ( ) formation on caesiated surfaces d) approaches for collision integral calculation of highly excited states interactions a) transport properties of air plasma with electronically excited states b) transport of radiation c) negative ion source modeling improvements