Transition from Collisional to Collisionless Regimes in Interpenetrating Plasma Flows on the National Ignition Facility

Transition from Collisional to Collisionless Regimes in Interpenetrating Plasma Flows on the National Ignition Facility

Show other versions (1)

A study of the transition from collisional to collisionless plasma flows has been carried out at the National Ignition Facility using high Mach number (M>4) counterstreaming plasmas. In these experiments, CD-CD and CD-CH planar foils separated by 6–10 mm are irradiated with laser energies of 250 ...

Full description

Bibliographic Details
Main Authors: Ross, J. S., Higginson, D. P., Ryutov, D., Fiuza, F., Hatarik, R., Huntington, C. M., Kalantar, D. H., Link, A., Pollock, B. B., Remington, B. A., Rinderknecht, H. G., Swadling, G. F., Turnbull, D. P., Weber, S., Wilks, S., Froula, D. H., Rosenberg, M. J., Morita, T., Sakawa, Y., Takabe, H., Drake, R. P., Kuranz, C., Gregori, G., Meinecke, J., Levy, M. C., Koenig, M., Spitkovsky, A., Zylstra, A. B., Park, H.-S., Petrasso, Richard D, Li, Chikang, Sio, Hong Weng, Lahmann, Brandon James
Other Authors: Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
Format: Article
Language:English
Published: American Physical Society 2017
Online Access:http://hdl.handle.net/1721.1/109179
https://orcid.org/0000-0002-1020-3501
https://orcid.org/0000-0002-6919-4881
https://orcid.org/0000-0001-7274-236X
Description
Summary:A study of the transition from collisional to collisionless plasma flows has been carried out at the National Ignition Facility using high Mach number (M>4) counterstreaming plasmas. In these experiments, CD-CD and CD-CH planar foils separated by 6–10 mm are irradiated with laser energies of 250 kJ per foil, generating ∼1000  km/s plasma flows. Varying the foil separation distance scales the ion density and average bulk velocity and, therefore, the ion-ion Coulomb mean free path, at the interaction region at the midplane. The characteristics of the flow interaction have been inferred from the neutrons and protons generated by deuteron-deuteron interactions and by x-ray emission from the hot, interpenetrating, and interacting plasmas. A localized burst of neutrons and bright x-ray emission near the midpoint of the counterstreaming flows was observed, suggesting strong heating and the initial stages of shock formation. As the separation of the CD-CH foils increases we observe enhanced neutron production compared to particle-in-cell simulations that include Coulomb collisions, but do not include collective collisionless plasma instabilities. The observed plasma heating and enhanced neutron production is consistent with the initial stages of collisionless shock formation, mediated by the Weibel filamentation instability.

Similar Items