Николай Геннадиевич Басов (К семидесятилетию со дня рождения), Андреев А.Ф., Кадомцев Б.Б., Келдыш Л.В., Крохин О.Н., Осипов Ю.С., Попов Ю.М.

The formation of craters in targets of various materials under the action of a high-power neodymium-laser pulse at radiation intensities from 1010 to 1014 W/cm2 was studied experimentally and theoretically. The interaction between the laser beam and solid targets is investigated to determine the efficiency of the ablation loading of various materials and the transformation of the laser energy into the energy of a shock wave.

The current status of laser thermonuclear fusion research in the leading world scientific centers is characterized by the development of superhigh-power multi-channel laser facilities of megajoule pulse-energy level. The development of such laser installations operating in the pulse-repetition mode with a large number of laser beams, which are necessary for high-symmetry irradiation of a spherical thermonuclear target, is an extremely difficult physical and engineering problem. The concept of a special laser with a controllable function of mutual coherence of radiation is proposed. The studies performed demonstrate that a laser based on such a principle has a number of advantages as compared to the conventional schemes of lasers. In particular, the optical scheme of the laser is significantly simplified, and the cost of the output-energy unit is reduced by several times. The influence of radiation coherence on the homogeneity of the thermonuclear target irradiation is analyzed. The feasibility of suppressing the small-scale self-focusing without application of spatial filtration is shown. A module of the laser facility has been triggered to check the validity of the principles proposed for constructing a laser driver for power stations, and the first experimental results are reported. The possibility of controlling the coherence of laser beams used in ICF experiments without violation of the laser--target system matching is demonstrated, as well as controlling the distribution of the laser radiation intensity in the lens focus.

Представлены результаты экспериментов и теоретических исследований по образованию кратеров в мишенях из различных материалов при воздействии мощного импульса неодимового лазера в диапазоне интенсивностей от 10 10 до 10 14 Вт/см 2. Исследования взаимодействия лазерного пучка с твердыми мишенями проводились с целью определения эффективности абляционного нагружения материалов и трансформации лазерной энергии в энергию ударной волны.

The results of experimental and theoretical studies of operation regimes of a pulsed chemical D2–F2–CO2 UV initiated laser are presented. The influence of particular mixture components, the power of the UV radiation source, and the resonator's characteristics on the output radiation parameters are experimentally studied on the “Kaiman” setup. The results of theoretical simulation obtained using the proposed scheme correspond sufficiently to those obtained experimentally. A description is given of the pulsed D2–F2–CO2 UV initiated laser “Flash-1” that provides for radiation pulses of 18 J with a 2.6–3.5 μs duration in the 10-micron range. A detailed description is given of the precision diagnostics of dark reactions occurring during the mixture preparations and affecting the efficiency of energy extraction in the course of generation.

The dynamics of an electromagnetic field in an unsteady cylindrical resonator with perfectly conducting and impedance walls is considered. Exact solutions are found for fields as functions of time. Conservation of photon numbers during the compression is shown.

The design and parameters of the UV-preionized discharge module “Katran” are described. A particular feature of the scheme is a high-voltage pulse formation technique for sharp discharge current ignition to stabilize the self-sustained glow discharge. The free-running laser based on the discharge module allows one to obtain high specific laser power exceeding 145 MW/liter in the P(20) line for the 10-μm band for an active volume of 3 liters. Duration of the first spike of generation is 30 ns FWHM and energy content is about 65% of the total pulse energy. The high reliability and reproducibility of the module's operation for a wide range of parameters ensures laser suitability for different scientific and technical applications.

Targets with low degrees of compression, such as those with internal energy deposition, two-stage conical targets for lasers emitting pulses of duration of the order of 100 ns, and multilayer shell targets for short-pulse long-wavelength CO2 and CO lasers may prove acceptable for hybrid thermonuclear reactors with high values (of the order of 103) of the gain in the blanket. Estimates and one-dimensional calculations of the compression of such targets are reported for the laser radiation energy range 0.2–2 MJ.

Preliminary results of investigation of modified oscillator of the D2ML Nd glass laser facility are presented. Using so called Wood's selector Modification of oscillator have been done to broad a bandwidth generation. The diagnostic techniques for the oscillator investigations are described. Some considerations to study temporal and spatial evolution of the broad bandwidth laser pulse during D2ML path propagation are formulated.

An Yb,Nd-doped flashlamp pumped crystal laser for an average-power operation is discussed. Excitation transfers from Nd3+ to Yb3+ ions in garnet offer stored energies near 1 J/cm3, pulse repetition rate of 1 Hz.

Two unconventional approaches for the inertial confinement laser fusion are studied theoretically: 1) the inner energy input into a laser target shell with the pulse duration about 0.1 ns and 2) the high aspect ratio targets irradiated by a long pulse of 100 ns.

It is necessary to reach large gains in laser target (G) to get useful energy in a fusion reactor. Using the fission blanket in a reactor allows one to increase the energy gain. The first Russian projects of laser fission-fusion reactor were studied. It was suggested to use a two-cascade hybrid reactor scheme, allowing one to reach gain in fission blanket more than 1000. As a result it will be possible to use laser target with G on the order of 0.1 - 1 in such type of a reactor. It was suggested to target the design for the 'ignition' experiment at the laser energy 0.1 - 0.3 MJ. It was a high aspect ratio cryogenic direct driven target. But it is necessary to use a lot of laser beams around the target to provide spherical symmetry of laser irradiation. Large surface 'will be lost' for fission blanket. In addition the laser pulse should have a sharp time profile. It is necessary to use about five-to-ten times more laser energy to get 'ignition' in indirect driven target. The new target design, named 'Greenhouse target,' was suggested. It is a very important problem to compensate the negative influence of holes on compression symmetry. It was suggested to use the target with 'relief' to compensate this effect. This target design is studied now. We are studying four alterative approaches to the laser target design for hybrid reactor: (1) the target with inner laser energy input; (2) high aspect ratio target for laser with pulse duration about 100 ns; (3) conic target; (4) exploding pusher spherical or conic targets for carbon-dioxide laser. The numerical simulations were made by using Lagrange code 'ATLANT'.