Kinetic processes in a highly-ionized non-equilibrium hydrogen plasma

Abstract

The work represents a ramified kinetic scheme of plasma chemical processes in a non-equilibrium hydrogen plasma that allows one to model in detail the dynamics of an electric discharge in a molecular gas. The scheme describes processes of interaction of electrons with heavy particles (including a vast set of processes of electronic-vibrational excitation of hydrogen molecules by electron impact), vibrational kinetics of the H2 molecules and processes with participation of hydrogen atoms, positive and negative ions.The possibility of reaching a high level of vibrational non-equilibrium of the molecular component of the gas under conditions characterized by high values of gas temperature and concentration of atomic hydrogen (which is an effective quencher of the vibrational levels of the H2(X) particles) is demonstrated by the examp!e of the pu!sed high-current low-pressure discharge. Such a possibility is conditioned by the high efficiency of the processes of vibrational excitation of hydrogen molecules via singlet electronic terms. It is also shown that quick gas heating during~the discharge at sufficiently high electron energy (T. 2 2 eV) is substantially governed by the processes of dissociative excitation of electronic states of the hydrogen molecules by direct electron impact.

Atom and Ion Chemistry in Low Pressure Hydrogen DC Plasmas

“…Many studies have also been devoted to the atomic hydrogen produced in these plasmas, which is of relevance for film deposition processes. [5][6][7][8] The dynamics of internally excited states of H 2 [9][10][11][12][13][14][15][16][17][18] and its close relationship to the production of H -ions by dissociative electron attachment have been also addressed by various groups. [19][20][21] Theoretical and experimental investigations over decades have provided much information on fundamental processes relevant to H 2 plasmas (see for instance refs 22-27 and references therein), but there is still a dearth of basic data specially on state-resolved cross sections and on gas surface interactions, and many uncertainties remain about the coupling between the plasma chemistry and the discharge dynamics.…”

Rovibrational distribution of H2 in low temperature plasma: the dependence on the plasma parameters

“…doi:10.1016/j.jnucmat.2004. 10.025 low electron energy range of the order of several electron Volt, the incident electrons can attach to the target hydrogen molecules to form negative H À 2 molecules which are mainly in the resonant electronic states of 2 R þ g and 2 R þ g . These H À 2 molecules can either be dissociated or detach the attached electrons to return to H 2 .…”

“…For the process of vibrational exchange, according to [10], the forward v-v reaction rate coefficients in Table 1 can be approximated by:…”

Numerical simulation of the kinetics of dissociation and ionization of molecular hydrogen in the penning discharge plasma with the use of the reduced kinetic model

“…Available papers related to the numerical simulation of atomic-molecular composition of plasma in ion sources mainly concern the devices with high gas-discharge current used in fusion reactors, as well as sources of H  ions [1,5]. At the same time many ion sources used in the gas-filled neutron sources operates at relatively low discharge current ( 0.1 2 mA I  ) and the use of the detailed kinetic schemes in the compute-intensive 2D and 3D PIC models for calculation of the plasma chemical composition appears to be difficult.…”