(Color online) Layout of plasma conductivity measurements.
(Color online) Oscillograms of the laser pulse (2) and photocurrent signals (1) for different input impedances and laser intensities , 10 ns/div (a); , 50 s/div (b); and , 500 s/div (c).
(Color online) Photoelectron signal jump vs. applied DC voltage U for a fixed drift length l = 4 mm (a) and vs. l for a fixed U = 250 V (b).
(Color online) Electron density vs. laser intensity I. Different symbols correspond to experiments with various focusing conditions.
(Color online) Layout of the double pulse experiments.
(Color online) Oscillograms of the combined laser pulse (1) and photoelectron current on matched oscilloscope input (2).
(Color online) Electron photodetachment ratio vs. averaged intensity of the second laser pulse . Intensity of the first pulse W/cm2 and ns.
(Color online) Various setups of experiments on the MW radiation propagation in plasma waveguides.
(Color online) Laser-beam prints on a photo paper after a two-lens telescope (left) and a two-axicon telescope (right).
(Color online) Signals from the MW receiver (upper beam) and laser pulse (lower beam): upper ((a) and (b)) for the setup in Fig. 8(a) and lower ((c) and (d)) for the setup in Fig. 8(d). The distance to the receiver L = 12 m.
(Color online) Schematic view of the MW radiation propagation in a cylindrical (left) and conical (right) plasma waveguide.
(Color online) Diffraction angle and angles of total internal reflection from the plasma–air interface vs the MW radiation wavelength. The MW radiation diffraction angle (1), atmospheric air (2), and hydrocarbons added (3).
Characteristic attenuation length of the lower axial-symmetric and axial-asymmetric hybrid sliding modes of MW radiation vs. its wavelength at plasma density cm−3 and waveguide radius R = 5 cm (a), 10 cm (b), and 30 cm (c).
Characteristic threshold values (relation (12)) of the waveguide radius vs. the density of wall plasma for MW radiation wavelengths mm (a) and mm (b).
Characteristic attenuation length of the lower axial-symmetric and axial-asymmetric hybrid sliding modes of MW radiation with the wavelength mm vs. the density of waveguide wall plasma at waveguide radii R = 5 cm (a), R = 10 cm (b), and R = 30 cm (c).
Characteristic attenuation length of the axial-symmetric mode of MW radiation with wavelength mm vs. the relative plasma-waveguide-wall thickness . The result is obtained by numerically solving the dispersion Eq. (29) at plasma density cm−3 and waveguide radius R = 10 cm.
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