scholarly journals B2.5-Eunomia simulations of Magnum-PSI detachment experiments: II. Collisional processes and their relevance

2021 ◽  
Author(s):  
Ray Chandra ◽  
Hugo J. de Blank ◽  
Paola Diomede ◽  
Egbert Westerhof
Keyword(s):  
Target Chamber ◽  
Small Contribution ◽  
Electron Cooling ◽  
Dissociative Attachment ◽  
Vibrationally Excited ◽  
Temperature Regimes ◽  
Recombination Processes ◽  
Separate Electron ◽  
Particle Momentum ◽  
Three Body

Abstract Detachment is achieved in Magnum-PSI by increasing the neutral background pressure in the target chamber using gas puffing. The plasma is studied using the B2.5 multi fluid plasma code B2.5 coupled with Eunomia, a Monte Carlo solver for neutral species. This study focuses on the effect of increasing neutral background pressure to the plasma volumetric loss of particle, momentum and energy. The plasma particle and energy loss almost linearly scale with the increase of neutral background pressure, while the momentum loss does not scale as strongly. Plasma recombination processes include molecular activated recombination (MAR), dissociative attachment, and atomic recombination. Atomic recombination, which includes radiative and three-body recombination, is the most relevant plasma process in reducing the particle flux and, consequently, the heat flux to the target. The low temperature where atomic recombination becomes dominant is achieved by plasma cooling via elastic H+-H2 collisions. The transport of vibrationally excited H2 molecules out of the plasma serves as an additional electron cooling channel with relatively small contribution. Additionally, the transport of highly vibrational H2 has a significant impact in reducing the effective MAR and dissociative attachment collision rates and should be considered properly. The relevancy of MAR and atomic recombination occupy separate electron temperature regimes, respectively, at Te = 1.5 eV and Te = 0.3 eV, with dissociative attachment being relevant in the intermediary. Plasma cooling via elastic H+-H2 collisions is effective at Te ≤ 1 eV.

scholarly journals Atomic-state-dependent screening model for hot and warm dense plasmas

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Fuyang Zhou ◽  
Yizhi Qu ◽  
Junwen Gao ◽  
Yulong Ma ◽  
Yong Wu ◽  
...  
Keyword(s):  
Radiation Transport ◽  
Atomic State ◽  
Many Body ◽  
Dense Plasmas ◽  
Screening Model ◽  
State Dependent ◽  
Recombination Processes ◽  
Three Body ◽  
Many Body Interactions ◽  
Body Recombination

AbstractAn ion embedded in warm/hot dense plasmas will greatly alter its microscopic structure and dynamics, as well as the macroscopic radiation transport properties of the plasmas, due to complicated many-body interactions with surrounding particles. Accurate theoretically modeling of such kind of quantum many-body interactions is essential but very challenging. In this work, we propose an atomic-state-dependent screening model for treating the plasmas with a wide range of temperatures and densities, in which the contributions of three-body recombination processes are included. We show that the electron distributions around an ion are strongly correlated with the ionic state studied due to the contributions of three-body recombination processes. The feasibility and validation of the proposed model are demonstrated by reproducing the experimental result of the line-shift of hot-dense plasmas as well as the classical molecular dynamic simulations of moderately coupled ultra-cold neutral plasmas. Our work opens a promising way to treat the screening effect of hot and warm dense plasma, which is a bottleneck of those extensive studies in high-energy-density physics, such as atomic processes in plasma, plasma spectra and radiation transport properties, among others.

scholarly journals Atomic hydrogen III—The energy efficiency of atom production in a glow discharge

1937 ◽  
Vol 163 (914) ◽  
pp. 424-454 ◽  
Keyword(s):  
Glow Discharge ◽  
Closed System ◽  
Atomic Hydrogen ◽  
Empirical Relation ◽  
Power Input ◽  
Degree Of Dissociation ◽  
Recombination Processes ◽  
Dark Space ◽  
The Difference ◽  
Three Body

There seems to have been a tendency amongst workers on the use of the glow discharge as a source of atomic hydrogen to regard the current or power as determining the degree of dissociation of the gas, i. e. the equi­librium H 2 ⇌2H. It is clear, however, that the discharge itself determines only the rate of production of atoms, whereas the degree of dissociation depends also on the rate of removal of atoms by pumping and by recombina­tion processes which are independent of the discharge. The two homogeneous recombination processes are those resulting from three-body collisions be­tween three atoms and between two atoms and a molecule; in addition, there is a heterogeneously catalysed reaction in which the walls of the tube act as the energy acceptor. Attempts to connect electrical conditions with degree of dissociation have been made by Crew and Hulburt (1927) and by Wrede (1929), but the above remarks show that only empirical relationships can be hoped for. In Crew and Hulburt’s experiments, the degree of dissociation was estimated by measuring the change of pressure in a closed system on passing a discharge. A correction for temperature was applied, which was based on the erroneous idea that the rise of temperature due to discharge in helium is about the same as that in hydrogen at the same pressure and power input. The method of determining the pressure depended on an empirical relation between pressure and the length of the cathode dark space in an auxiliary discharge connected to the main system ; but since the cathode dark space has not a sharply defined boundary, and the degree of dissociation is calculated from the difference of two pressures measured in this way, considerable error is possible. Furthermore, in a closed system, the rate of production of atoms is equal to the rate of recombination; and since these workers relied on a water-on-glass film to inhibit heterogeneous recombination, and as the power input was 200-1000 W, the catalytic activity of the walls must have been very variable and large (Part II). Crew and Hulburt’s curves con­necting degree of dissociation with pressure and power input cannot, there­fore, be credited with quantitative significance.

Rates of three-body ionic recombination processes in the rare-gas-halides

1981 ◽  
Vol 14 (12) ◽  
pp. 2053-2057 ◽  
Author(s):  
C G Christov ◽  
V L Lyutskanov ◽  
I V Tomov
Keyword(s):  
Rare Gas ◽  
Recombination Processes ◽  
Three Body

scholarly journals New electron energy transfer and cooling rates by excitation of O2

1998 ◽  
Vol 16 (8) ◽  
pp. 1007-1013 ◽  
Author(s):  
A. V. Pavlov
Keyword(s):  
Energy Transfer ◽  
Electron Energy ◽  
Cross Sections ◽  
Vibrational Excitation ◽  
Electron Cooling ◽  
Vibrationally Excited ◽  
Cooling Rates ◽  
Production Frequency ◽  
Electron Energy Loss ◽  
Analytical Expressions

Abstract. In this work I present the results of a study of the electron cooling rate, the production rates of vibrationally excited O2, and the production frequency of the O2 vibrational quanta arising from the collisions of electrons with O2 molecules as functions of the electron temperature. The electron energy transfer and cooling rates by vibrational excitation of O2 have been calculated and fitted to analytical expressions by use of the revised vibrationally excited O2 cross sections. These new analytical expressions are available to the researcher for quick reference and accurate computer modeling with a minimum of calculations. It is also shown that the currently accepted rate of electron energy loss associated with rotational transitions in O2 must be decreased by a factor of 13.

Atmospheric electron–ion and ion–ion recombination processes

1969 ◽  
Vol 47 (10) ◽  
pp. 1711-1719 ◽  
Author(s):  
Manfred A. Biondi
Keyword(s):  
Dissociative Recombination ◽  
Laboratory Studies ◽  
Ion Temperature ◽  
Air Ions ◽  
Atomic Ions ◽  
Recombination Processes ◽  
D Region ◽  
Ion Recombination ◽  
Three Body ◽  
Large Coefficient

The electron–ion and ion–ion recombination processes of importance in the upper atmosphere are considered, and available laboratory experimental and theoretical information concerning the relevant processes is discussed. For atomic ions the principal electron–ion recombination process is radiative, with theory indicating that the two-body coefficient at ∼200 °K is ∼10−11 cm3/s and decreases with increasing electron temperature. Microwave afterglow/mass spectrometer studies of diatomic ionospheric ions (e.g. NO+, O2+, and N2+) show a loss by dissociative recombination with a coefficient substantially in excess of 10−7 cm3/s at 250 °K and decreasing with increasing electron and ion temperature. There is some evidence from flame studies that H3O+ ions exhibit a very large coefficient (10−6–10−5 cm3/s) at 300 °K. Ion–ion recombination evidently proceeds by mutual neutralization, with laboratory studies of ions such as NO+ and NO2− indicating a two-body coefficient of the order of 10−7 cm3/s at 300 °K. In the lower D region, three-body Thomson recombination may be important, since laboratory studies of "air" ions indicate a three-body coefficient of ∼2 × 10−25 cm6/s at 300 °K.

Evidence for the onset of three-body decay in photodissociation of vibrationally excited CHFCl2

2001 ◽  
Vol 114 (20) ◽  
pp. 9033-9039 ◽  
Author(s):  
Xiangling Chen ◽  
Ran Marom ◽  
Salman Rosenwaks ◽  
Ilana Bar ◽  
Tina Einfeld ◽  
...  
Keyword(s):  
Vibrationally Excited ◽  
Three Body

Laboratory studies of electron attachment and detachment processes of aeronomic interest

1969 ◽  
Vol 47 (10) ◽  
pp. 1783-1793 ◽  
Author(s):  
A. V. Phelps
Keyword(s):  
Cross Sections ◽  
Ion Beam ◽  
Electron Attachment ◽  
Negative Ions ◽  
High Energy ◽  
Low Energy ◽  
Rate Coefficients ◽  
Dissociative Attachment ◽  
Three Body ◽  
Energy Processes

Techniques for the study of electron attachment and detachment are reviewed. The rate coefficients for the various processes of aeronomic interest are then discussed. The rates of three-body and dissociative attachment by thermal electrons have been successfully determined by swarm techniques and by high frequency studies of electrons produced by high energy particles and by photoionization. Collisional and associative detachment rates for thermal energy negative ions have been measured using the swarm and flowing afterglow techniques. Radiative attachment rates for some atmospheric negative ions have been calculated from measurements of photodetachment cross sections using crossed photon and ion beam techniques. Electron beam studies and measurements of ion kinetic energy have provided much useful information regarding the dissociative attachment process and the structure of molecular negative ions. Rate coefficients for low energy processes such as the three-body attachment to O2, the radiative attachment to O, and the associative detachment of O− in collisions with various atmospheric gases are reasonably well known. Other possibly important low energy processes, such as dissociative attachment to O3, radiative attachment to O2, and the associative detachment of O2− are less well known.

Laserspektroskopische Untersuchungen an nicht-stabilisierten N2(B3IIg, ν; = 13)-Molekülen / Laser Spectroscopic Studies on Non-stabilized N2(B3IIg, ν; = 13) molecules

1976 ◽  
Vol 31 (6) ◽  
pp. 673-674
Author(s):  
K. H. Becker ◽  
H. Engels ◽  
T. Tatarczyk
Keyword(s):  
Detection Limit ◽  
Emission Spectroscopy ◽  
Spectroscopic Studies ◽  
Rotational Analysis ◽  
Tunable Dye Laser ◽  
Recombination Processes ◽  
Three Body ◽  
Laser Spectroscopic ◽  
Body Recombination ◽  
Better Than

Unstabilized N2(B3IIg, ν = 13) quasi-molecules were analysed by excitation with a tunable dye-laser into the N2(C3IIu) state and observation of the following fluorescence to N2(B3IIg, ν) levels. The quasi-molecules are in equilibrium with the free nitrogen atoms. The detection limit of this technique is 105 molecules/cm3. By the same method, a rotational analysis of molecules stabilized into (B3IIg, ν ≦ 12) levels by three-body recombination processes was achieved with a resolution better than that reached by emission spectroscopy of the Lewis-Rayleigh afterglow

Sign in / Sign up

Export Citation Format

Share Document