Interferometry at 400 nm in jet: (a) the interferogram of jet around after valve opening; (b) after subtraction of reference interferogram taken with closed valve (phase shift map).
Evolution of plasma created in (a) nitrogen and (b) hydrogen gas jets by 90 mJ, 120 fs laser pulse. Initial molecular density in jets is represented by color scale. The vertical bar is shown to indicate the size and location of laser beam expected from optical delay of the probe and the block arrow on the left indicates the direction of the incoming pulse.
(a) Evolution of OFI plasma in jet presented by snapshots of interferograms: from top to bottom at 2.33, 3.0, 3.33, 4.33, and 5.0 ps delays indicated by white bar presenting the expected position of the laser pulse. Electron density irregularities are marked with thin-line arrows and the block arrow on the left indicates the direction of the incoming pulse. (b) The distribution of initial nitrogen molecular density along the propagation axis.
Evolution of average electron density in (a) nitrogen and (b) hydrogen gas jets. The maximum expected value of plasma density (dashed lines) along the laser propagation axis calculated from measured initial gas density in assumption of getting ten electrons from each molecule and for totally striped of hydrogen atoms. The actual delay for each density profile is represented by position of roof mirror in the optical delay line.
Comparison of (a) PGC simulation and (b) fully explicit simulation of pulse propagation in tunnel-ionized nitrogen. The data are evaluated at before any severe disruptions take place. is the cold wave breaking field.
Laser electric field after propagation in nitrogen for (a) 1.8 ps and (b) 3.3 ps. is the cold wave breaking field. The back third of the computational region is not shown.
Electron density due to tunnel ionization of nitrogen atoms after (a) 1.8 ps propagation and (b) 3.3 ps propagation. The thin vacuum regions near the edges of the computational box are due to the perfectly matched layers. In reality the plasma would extend beyond the transverse boundaries of the box. The back third of the computational region is not shown.
Axial variation in electron density in nitrogen jet. The maximum expected value (based on quintuple ionization of nitrogen atoms) is shown as a dashed line.
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