Nuclear-pumped Lasers Research Articles

Compact nuclear-driven semiconductor reactor/laser system

A model for a solid state nuclear pumped laser (SSNPL) has been developed. The laser model includes the spatial inhomogeneities of electron-hole pairs generated by fission products. A MCNP model was produced which transported the 20 most common U-235 fission fragments to dictate the 1-dimensional spatial inhomogeneity. The MCNP model included a variety of thicknesses to the layers involved. Core properties include a minimally critical cubic bare nuclear core which has dimensions less than one cubic meter on a side and laser thresholds in the sub-megawatt range. Laser efficiencies ranged from 2 to 5%. The SSNPL has the potential to be compact, low mass and efficient making it a promising space-based laser system.

Cadmium Vapor Concentration and Lifetime of the Upper Active Level of a He–Cd Nuclear-Pumped Laser at the 5s2 2D5/2–5p2P3/2 Cd II Transition

Cadmium Vapor Concentration and Lifetime of the Upper Active Level of a He–Cd Nuclear-Pumped Laser at the 5s2 2D5/2–5p2P3/2 Cd II Transition

Концентрация паров кадмия и время жизни верхнего рабочего уровня He-Cd-лазера с ядерной накачкой на переходе 5s-=SUP=-2-=/SUP=- -=SUP=-2-=/SUP=-D-=SUB=-5/2-=/SUB=--5p-=SUP=-2-=/SUP=-P-=SUB=-3/2-=/SUB=- Cd II

Experimental method is described and results of measurement of the cadmium vapor concentration in a nuclear pumped He-Cd laser on the cadmium ion transition with wave length 0.441 μm are presented . It is shown that observed concentration is about ten times less then saturated one for given temperature of laser cuvette. On the base of obtained data the conclusion is made that life time of the upper level for CdII 5s2 2D5/2 -5p2P3/2 transition in a optimum condition of He-Cd laser operation equals about 0.5 μs.

Optical Inhomogeneities in Nuclear-Pumped Lasers

The major steps of computational studies of optical inhomogeneities in nuclear-pumped lasers are considered.

Energy Deposition in the Cavities of Lasers with Nuclear Pumping

A review of the results of experimental investigations on the determination of the energy deposition in cavities of nuclear-pumped lasers is presented. We consider the methods of (1) pressure jump, (2) interferometry, and (3) string calorimeter. A comparative analysis of the results of experiments and calculations to determine the energy deposition of fission fragments has been carried out.

Key Research Results for Nuclear-Pumped Lasers at VNIIEF

Key Research Results for Nuclear-Pumped Lasers at VNIIEF

Characteristics of the Active Element of a Nuclear-Pumped Cadmium-Vapor Laser

The influence of the active-element characteristics on the efficiency of a cadmium-vapor laser pumped by uranium fission fragments was studied experimentally. The 441.6 nm laser radiation of the cadmium ion was studied. An aluminum tube with diameter ~15 mm and an inner coating of U3O8 with thickness 3 mg/cm2 served as the active element. The neutron source was the BARS-6 pulsed, fast, aperiodic, self-extinguishing reactor. A comparison of the efficiency of the laser with similar data previously obtained under the same conditions for a 48 mm in diameter active element with a ~10 mg/cm2 thick uranium metal coating shows that a three-fold reduction of the diameter of the active element and uranium coating thickness results in a 2.5-fold increase of the laser efficiency. This confirms the hypothesis of internal losses of laser radiation in the active element of a fission-fragment pumped laser which are due to the scattering of light by transverse sound waves of the gas density which appear during a pumping pulse because of the radial non-uniformity of the energy input.

Problem of nuclear-laser power engineering and methods of their solution

The concept of a high power reactor-laser system based on a nuclear pumped optical quantum amplifier (OKUYaN) was formulated at IPPE in the mid-1980-ies. The idea amounted to the use of wide-aperture OKUYaN as an amplifier within the already well-known “master laser – two-pass amplifier with phase conjugation” scheme. The structure of such an amplifier includes a system of two neutron-coupled units – an ignition reactor (RB) and a nuclear pumped laser amplifier (LB). The ignition unit is a compact multi-core pulsed fast neutron reactor. The laser amplifier unit operates on thermal neutrons and, with regard to the neutronics, it is a subcritical booster zone of the ignition reactor unit. Unique reactor-laser complex incorporating demonstration sample of a pulsed reactor-laser system based on OKUYaN (test facility “Stand B”) having no analogues anywhere in the world, was developed and put into operation at IPPE in 1999 for the purpose of substantiation of basic principles of the OKUYaN concept and demonstration of the possibility of its practical implementation, as well as verification of calculation codes and development of relevant equipment elements. Problems overcome in the development and construction of “Stand B” test facility, the choice and justification of the neutronics and laser characteristics of the OKUYaN demonstration sample are discussed in the present paper. Provided are the results of a detailed computational-experimental study of the demonstration sample characteristics, the data from systems studies of direct conversion of nuclear fission energy into laser radiation energy in complex reactor-laser devices and the results of examination of prospects for the development of nuclear-laser power engineering.

Effect of Thermal Conductivity of Structural Materials on the Efficiency of Plate Radiators of Multichannel Modules of Nuclear-Pumped Lasers

Effect of Thermal Conductivity of Structural Materials on the Efficiency of Plate Radiators of Multichannel Modules of Nuclear-Pumped Lasers

Thermal to optical energy conversion: A multi megawatt carbon dioxide laser driven by an extremely high temperature gas cooled reactor

In the conversion of ionizing radiation into energy, the production of heat is the most common first step in energy conversion systems, but it is also possible to use ions and excited states as the first step. The difference being that nearly all of the energy content of ionizing radiation is converted to heat but only 40–50% of the energy content of ionizing radiation is converted into ions and excited states. Conversion of the energy contained in ionizing radiation into ions and excited states starts out at a considerable disadvantage. Nuclear-pumped lasers have typically depended on the conversion of ionizing radiation into ions and excited states as a first step. Among the reasons that nuclear-pumped lasers have had low system efficiencies (1–2.5%) is the considerable inefficiencies in producing ions and excited states from ionizing radiation. A nuclear-pumped laser system which uses heat produced from the energy content of ionizing radiation as the driver for the laser system is described in this paper. The conversion of heat into vibrational states in molecular nitrogen allows energy to be stored in a long lived molecular state which can then be transported spatially where its energy is collisionally conveyed to carbon dioxide molecules in a resonance transfer process to produce the carbon dioxide upper laser level. The carbon dioxide laser emits a laser beam with a wavelength centered at 10.4 μm. The nitrogen vibrational state and its resonance conversion into the carbon dioxide upper laser level is one of nature's most efficient processes in laser physics (with laser efficiencies approaching ∼20% primarily being driven by the resonance process-extremely high for a laser). The laser system described here takes advantage of this highly efficient mechanism for conversion of thermal energy to optical energy. The feasibility of using nuclear rocket core technology for the generation of high temperature gas flows to power this thermal to optical conversion process is described. This study indicates that the thermal to optical conversion process can lead to a carbon dioxide laser with efficiencies on the order of 7% or perhaps better. Such a system would have potential applications in power beaming, space propulsion, asteroid mining, asteroid deflection and potential military applications.

Measuring the Deceleration Parameter of the Fission Fragments in a Gaseous Environment for Uranium Coating the Laser-Active Element of the Laser with Nuclear Pumping

Abstract: In this paper the results of the practical definition of the braking parameter of uranium coating fission fragment in the active laser element of nuclear-pumped laser in a gaseous environment are presented. A description of the experimental method for removing the fission spectra of a NPL uranium coating is given. This method is based on measuring the fission fragments energy spectra emitted from the coating to a gas mixture with the help of a semiconductor detector. To calibrate the fission fragment sensors a californium source the fragments of which have a characteristic spectrum is used. The results of the analysis of the sections of the experimental spectra are presented. On the basis of the findings the theoretical model of the fission energy transfer process in a gaseous environment were checked. As the determining parameters in the modeling of this process, the pressure of the gas mixture in the cuvette with the source and the distance from the fission fragment source to the semiconductor sensors are chosen. The functional dependences of the obtained amplitude spectra on these parameters are determined. A mathematical description of the disperse energy fragment process is presented. The basis of this description is a two-parameter dependence.

Modeling of direct conversion of the uranium fission product kinetic energy to laser radiation energy in an argon–xenon dusty plasma with uranium nanoparticles

The process of direct conversion of the uranium fission product kinetic energy to laser radiation (LR) energy in a moving argon–xenon laser-active gas medium containing uranium nanoparticles has been investigated.A model and a method have been developed to solve numerically equations for the model of direct uranium fission product kinetic energy conversion to laser radiation energy in such medium. Spatiotemporal evolutions of the uranium nanoparticle concentration distribution have been calculated for different gas flow velocities and uranium nanoparticle sizes.Kinetic processes in a moving argon–xenon laser-active gas medium containing uranium nanoparticles have been studied.It is the first time that amplifying properties of a laser-active spatially heterogeneous nuclear-excited moving argon–xenon medium, containing uranium nanoparticles and irradiated by neutrons, have been studied. As shown by the investigation results, the LR intensity amplification may be sevenfold and more in steady-state conditions. Such a high value makes it possible to state that this medium can be used not only in a nuclear-pumped laser but also in the mode of a single-pass nuclear-pumped laser amplifier.

From the first nuclear power plant to fourth-generation nuclear power installations [on the 60th anniversary of the World’s First nuclear power plant

Successful commissioning in the 1954 of the World’s First nuclear power plant constructed at the Institute for Physics and Power Engineering (IPPE) in Obninsk signaled a turn from military programs to peaceful utilization of atomic energy. Up to the decommissioning of this plant, the AM reactor served as one of the main reactor bases on which neutron-physical investigations and investigations in solid state physics were carried out, fuel rods and electricity generating channels were tested, and isotope products were bred. The plant served as a center for training Soviet and foreign specialists on nuclear power plants, the personnel of the Lenin nuclear-powered icebreaker, and others. The IPPE development history is linked with the names of I.V. Kurchatov, A.I. Leipunskii, D.I. Blokhintsev, A.P. Aleksandrov, and E.P. Slavskii. More than 120 projects of various nuclear power installations were developed under the scientific leadership of the IPPE for submarine, terrestrial, and space applications, including two water-cooled power units at the Beloyarsk NPP in Ural, the Bilibino nuclear cogeneration station in Chukotka, crawler-mounted transportable TES-3 power station, the BN-350 reactor in Kazakhstan, and the BN-600 power unit at the Beloyarsk NPP. Owing to efforts taken on implementing the program for developing fast-neutron reactors, Russia occupied leading positions around the world in this field. All this time, IPPE specialists worked on elaborating the principles of energy supertechnologies of the 21st century. New large experimental installations have been put in operation, including the nuclear-laser setup B, the EGP-15 accelerator, the large physical setup BFS, the high-pressure setup SVD-2; scientific, engineering, and technological schools have been established in the field of high- and intermediate-energy nuclear physics, electrostatic accelerators of multicharge ions, plasma processes in thermionic converters and nuclear-pumped lasers, physics of compact nuclear reactors and radiation protection, thermal physics, physical chemistry and technology of liquid metal coolants, and physics of radiation-induced defects, and radiation materials science. The activity of the institute is aimed at solving matters concerned with technological development of large-scale nuclear power engineering on the basis of a closed nuclear fuel cycle with the use of fast-neutron reactors (referred to henceforth as fast reactors), development of innovative nuclear and conventional technologies, and extension of their application fields.

Mathematical simulation of the amplification of laser radiation in a nuclear-excited He – Ar plasma containing nanoclusters of uranium compounds

The possibility of applying dusty active media in nuclear-pumped lasers has been considered. The amplification of radiation in a nuclear-excited dusty He – Ar plasma is studied by mathematical simulation. The influence of nanoclusters on the component composition of the medium and the kinetics of the processes occurring in it is analysed using a specially developed kinetic model, including 72 components and more than 400 reactions. An analysis of the results indicates that amplification can in principle be implemented in an active laser He – Ar medium containing nanoclusters of metallic uranium and uranium dioxide.

Converting nuclear energy into the energy of coherent optical radiation

AbstractThis paper is devoted to the question of the conversion of nuclear energy into the energy of coherent optical radiation. The two possible ways to convert nuclear energy into laser radiation are discussed: direct and combined nuclear pumping. The concept of using laser gas active media capable of working with both direct and combined nuclear pumping is considered. The results of an investigation by Kazakh scientists on nuclear pumped lasers active media on bound–bound atomic transitions are presented.

Fast periodic-pulse reactor for high-power nuclear-pumped lasers

A concept for the IRM fast periodic-pulse reactor, which can be used as an ignition module for high-power nuclear-pumped lasers, is presented. The periodic-pulse operating regime of IRM is examined. The results of calculations of the parameters of the IRM which is under development are compared with the main characteristics of IBR-2. It is shown that IRM holds promise for use in high-power nuclear-pumped lasers.

Ignition reactor and pump pulse parameters in a reactor–laser system

The experience gained in operating a demonstration nuclear-pumped laser in stand B (Physics and Power- Engineering Institute (FEI)) with a pulsed ignition reactor based on the 235U BARS-6 reactor is analyzed. It is shown that laser block → ignition reactor neutron feedback coupling greatly limits the parameters of the pump pulse from the amplifier. A method is proposed for decreasing the feedback by replacing 235U with the threshold fissile element 237 Np in the ignition reactor. Such a reactor will increase by approximately 15-fold the energy and power of the pump pulse in the laser block of the demonstration reactor of the nuclear-pumped laser in stand B.

Determination of energy deposition into the cells of nuclear-pumped lasers

A review of experimental and analytical investigations of the energy deposition into the cells of nuclear-pumped lasers is presented. Three experimental techniques for energy deposit determination are considered: pressure jump method, interferometric method, and the method of string calorimeters. Comparative analysis of experimental and analytical data on the energy deposit is conducted.

Lasing characteristics of the Ar — Xe and He — Ar — Xe mixtures pumped by fission fragments

The lasing characteristics of the Ar — Xe and He — Ar — Xe mixtures emitting at the transitions of the Xe atom at 1.73 and 2.026 mkm upon pumping by fission fragments in the BARS-6 pulsed reactor are studied. We describe an experimental setup and methods for measuring laser beam parameters and characteristics of the active medium of the nuclear-pumped laser in the free-running and master oscillator — amplifier regimes. The dependences of the laser pulse energy on the resonator parameters and the composition and pressure of the working mixture are studied in the free-running regime. A method of modulating the input signal of a single-pass amplifier is proposed for obtaining lasing characteristics of active mixtures. The lasing characteristics of the Ar — Xe and He — Ar — Xe mixtures (the unsaturated gain, saturation intensity, conversion efficiency, etc.) are determined from experiments in the amplifier — oscillator regime and compared with the results reported in other papers.

Effect of the active-medium temperature on the kinetics of plasmachemical processes in directly nuclear-pumped xenon laser

The influence of the temperature of an active medium on the output characteristics of a directly nuclear-pumped laser on atomic transitions in xenon has been studied. It is shown that the quenching of generation before reaching a maximum of the pumping neutron flux is caused primarily by the temperature dependence of the reaction rate constant for the dissociation of heteronuclear ArXe+ ions upon collisions with buffer gas atoms.