Laser-Induced Photon-Branched Chain Reaction in a Chemically-Active Gas-Dispersed Medium

Table 1

Main properties and parameters of the HF-laser amplifier based on a PBCR. Here, 𝑟₀ and 𝑁₀ are the radius and concentration of the dispersed particles; 𝐼₀ and 𝜏_in are the intensity and duration of the initiating radiation; 𝐸_out and 𝐸_sp are the full (i.e., for the whole volume of the laser active medium) and the specific (i.e., per unit volume) energies of the output pulse of radiation; 𝑃_max is the maximum generated power; 𝑘_amp is the energy gain factor; 𝜏^𝐿 is the duration of the output pulse; 𝜏^𝐿_1/2 is the output pulse duration at half of the maximum power; 𝐼_thr is the threshold intensity for optical breakdown of the active medium.

Observed effects and properties of the laser	Calculated optimal laser parameters	Output characteristics
Effect of autowave spreading of a PBCR throughout the volume of the active medium as self-supporting cylindrical zones of photon branching	Ratio of the reagents as H2 : F2 = 1 : 2. The range of general pressures of the mixture is 𝑃 = 1–2.3 bar	𝐸out=1.5×2.3KJ 𝐸sp = 200–730 J/L𝑃max∼10^11W
Effect of the giant laser energy gain of 𝑘amp = 𝐸out/𝐸in ∼10^11, where 𝐸out and 𝐸in are the output and input energies, respectively	Ranges of Al particle radii and concentrations are, respectively: 𝑟0 = 0.09–0.4 𝜇m and 𝑁0 = 10^9–10^7 cm^−3	𝜏^𝐿≈800 ns 𝜏^𝐿1/2=100 ns.
Autonomous generation: a self-contained laser can be initiated by a small submicrojoule master oscillator powered by an accumulator	Performances of the master oscillator: input signal intensity 𝐼0=10^4 W/cm^2, energy of the input pulse 𝐸in = 2.18 × 10^−8 J, duration of the initiating pulse, 𝜏in=250 ns	𝑘amp = 𝐸out/𝐸in ≈10^7–10^11
Property of compactness, which is determined by the performances of the main laser units: minimal linear sizes of the cavity, ∼13  ×  14  ×  14 cm^3; minimal energy of the master oscillator, 𝐸in = 2.18 × 10^−8 J; minimal initially excited volume, 𝑉^minin = 10^−7 cm^3. The volume of the active medium is about 2L	Geometric parameters of the unstable telescopic cavity are as follows: number of passes, 𝑁𝑝 = 4; range of cavity lengths, 13–50 cm; range of magnification coefficients, 𝛽 = 1.5–2; diameter of the coupling aperture, 𝑑≤3 mm	The profile of the output pulse in the near-field zone is a torus, and in the far-field zone, the profile is Gaussian-like