Measurement and modeling of hydrogen molecule ro-vibrational accommodation on E-294 polycrystalline graphite

The loss rate of H2 and D2 internal ro-vibrational energy in collisions with an E-294 polycrystalline graphite surface is measured in a plasma-free environment. Accommodation coefficients are found to be approximately 0.01–0.2 for vibrational energy and somewhat larger, 0.05–0.2 for rotational energy, with a slight increasing trend seen with increasing surface temperature. Molecular dynamics simulations of the experiment give a total ro-vibrational accommodation rate of order 0.1, which is consistent with the data at higher surface temperatures.

[1]  E. Hollmann,et al.  Measurement and modeling of detached plasma cooling via ro-vibrational excitation of H2 neutrals in PISCES-A , 2007 .

[2]  H. Goan,et al.  Influence of an external magnetic field on the decoherence of a central spin coupled to an antiferromagnetic environment , 2007, 0706.0934.

[3]  S. Stuart,et al.  Low energy chemical sputtering of ATJ graphite by atomic and molecular deuterium ions , 2007 .

[4]  S. Brezinsek,et al.  Spectroscopic measurement of atomic and molecular deuterium fluxes in the DIII-D plasma edge , 2006 .

[5]  E. Hollmann,et al.  Measurement of cross-field power loss due to rovibrationally excited H2 in a detached hydrogen divertor plasma simulator , 2006 .

[6]  S. Brezinsek,et al.  Characterization of the deuterium recycling flux in front of a graphite surface in the TEXTOR tokamak , 2005 .

[7]  S. Holloway,et al.  Translation-to-rotational energy transfer in scattering of H2 molecules from Cu(111) surfaces , 2000 .

[8]  È. Roueff,et al.  ROVIBRATIONAL RELAXATION IN COLLISIONS BETWEEN H2 MOLECULES : II. INFLUENCE OF THE ROTATIONAL STATE OF THE PERTURBER , 1999 .

[9]  B. Lavrov,et al.  uv continuum emission and diagnostics of hydrogen-containing nonequilibrium plasmas , 1998, physics/9804008.

[10]  G. Brussaard,et al.  Diagnostics of the magnetized low-pressure hydrogen plasma jet: Molecular regime , 1996 .

[11]  R. Hardy,et al.  Vibrational relaxation in H2 molecules by wall collisions: Applications to negative ion source processes , 1985 .

[12]  Dan M. Goebel,et al.  Plasma surface interaction experimental facility (PISCES) for materials and edge physics studies , 1984 .

[13]  D. Reiter,et al.  Collision processes in low-temperature hydrogen plasmas , 2003 .

[14]  A. Pigarov.  Collisional Radiative Kinetics of Molecular Assisted Recombination in Edge Plasmas , 2002 .

[15]  Harold Y. Wachman,et al.  Dynamics of Gas-Surface Scattering , 1976 .