A new target configuration producing an effective population inversion at energy levels of Mg XI 1s3p and 1s4p

1988 ◽  
Vol 65 (6) ◽  
pp. 445-451 ◽  
Author(s):  
Zunqi Lin ◽  
Wenyan Yu ◽  
Weihan Tan ◽  
Wenhua Chen ◽  
Yuxia Zheng ◽  
...  
Keyword(s):  
Population Inversion ◽  
Energy Levels ◽  
Effective Population ◽  
Target Configuration

scholarly journals H2O Maser Pumping by Shock Waves

1992 ◽  
Vol 150 ◽  
pp. 245-247
Author(s):  
Jacques R.D. Lepine ◽  
Astrid Heske
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Population Inversion ◽  
Energy Levels ◽  
Rotational Energy ◽  
Molecular Gas ◽  
Cooling Process ◽  
Final Cool

We discuss a simple H2O maser pumping mechanism in which the population inversion of the masing levels takes place during the quick cooling of the gas behind a shock wave. The population of the rotational energy levels in the initial hot state and final cool state of the molecular gas, and the decay paths between levels are analysed to calculate the average number of 22 GHz photons emitted per H2O molecule in the cooling process.

scholarly journals Semiclassic Models of the Dissipative Regime of Instability and Superradiation of a Quantum Radiator System

2021 ◽  
Keyword(s):  
Density Matrix ◽  
Population Inversion ◽  
Open Resonator ◽  
Energy Levels ◽  
System A ◽  
Oscillatory Character ◽  
Radiator System ◽  
Integral Field ◽  
Local Value ◽  
Quantum Emitters

The paper discusses the similarity between dissipative generation and superradiance regimes for systems of excited quantum emitters placed in an open cavity. In the case of the existence of a resonator field due to reflections from the ends of the system, a dissipative generation regime is usually realized. In this case, the decrement of oscillations in the waveguide in the absence of radiators turns out to be greater than the increment of the arising instability of the system of radiators placed in the resonator. When describing this mode, the influence of the emitters on each other and the sum of their own fields is neglected. The resonator field forces the oscillators to emit or absorb quanta synchronously with it, depending on the local value of the population inversion. Lasing takes on a weakly oscillatory character due to an asynchronous change in the population inversion of the system of emitting dipoles (nutations), which have a ground and excited energy levels. To describe the process, the equations of the semiclassical theory based on the use of the density matrix are quite sufficient. In the case when there is no resonator or waveguide field, taking into account the eigenfields of the oscillators becomes essential. To simulate the superradiance process, large emitting particles are used, to describe which one should use the equations for the density matrix. It is shown that the interaction of quantum emitters in this case is due to electromagnetic fields under conditions when the overlap of their wave functions is insignificant. Equations are obtained that allow considering the process of interaction of emitters. When the emitters interact, an integral field is formed in the resonator, an increase in the intensity of which leads to synchronization of the emitters. It is shown that the characteristic times of the development of the process, as well as the attainable amplitudes of the excited fields for dissipative regimes of generation and regimes of superradiance of emitters filling an open resonator, are comparable.

Conditions for Population of Energy Levels Inversion when Active Medium Based on Gadolinium Isotopes Gd155 and Gd156 Couple Neutron Pumping

2018 ◽  
pp. 55-62
Author(s):  
I. V. Shamanin ◽  
M. A. Kazaryan
Keyword(s):  
Neutron Flux ◽  
Neutron Scattering ◽  
Active Medium ◽  
Isomeric State ◽  
Neutron Capture ◽  
Population Inversion ◽  
Energy Levels ◽  
Radiative Neutron ◽  
Radiative Neutron Capture ◽  
Isomeric States

The paper theoretically studies the possibility of energy transformation of fast and epithermal neutrons to energy of coherent photon radiation at the expense of a neutron pumping of the active medium formed by nucleus with longliving isomerous states. The channel of the nucleus formation in isomeric state as a daughter nucleus resulting from the nuclear reaction of neutron capture by a lighter nucleus is taken into consideration for the first time. Assessment of neutron flux spectrum parameters providing transition from the main state into one of the excited ones for the nuclei of isotopes54Xe130,10Ne22is made. It was shown that to transit the isotope nuclei into the excited state by forward neutron scattering on the nuclei it is necessary to “select” the isotopes not only with great specific energy of nucleons coupling but also with a small value of the neutron absorption cross section. Moreover, the paper performs the analysis of cross sections dependence of radiative neutron capture by the nuclei of gadolinium isotopes Gd155and Gd156. As a result, the speed of Gd156nuclei formation is stated to exceed the speed of their “burnup” in the neutron flux. It is provided by a unique combination of absorbing properties of two isotopes of gadolinium Gd155 and Gd156 in both thermal and resonance regions of neutron energy. We have formulated the conditions required for making isotope nuclei excited by forward neutron scattering on nuclei and for storing nuclei in excited states. The relation which allows estimating processes parameters of neutron capture by nuclei, formation and decay of nuclei isomeric states is obtained as a result of analytical solution of differential equations system of nuclide kinetics taking into account the decay of nuclei isomeric states. The paper makes the possibility analysis of neutron pumping of the participating medium created by the hafnium isotope nuclei. The properties of hafnium isotopes nuclei is found to do not allow providing conditions for population inversion of energy levels due to the formation of hafnium nuclei in isomeric state Hf178m2in the neutron flux. The paper shows the possibility of excess energy accumulation in the participating medium created by the nuclei of the pair of gadolinium isotopes Gd155and Gd156due to formation and storage of nuclei in isomeric state at radiative neutron capture by the nuclei of the stable isotope with a smaller mass. It is concluded that when the active medium created by gadolinium nuclei is pumped by neutrons with the flux density of the order of 1013cm-2·s-1, the condition of levels population inversion can be achieved in a few tens of seconds. The wave length of the radiation generated by the medium is 0.0006 nm. Sintered ceramics Gd2O3based on enriched in the 155-th isotope of gadolinium can be considered a possible active medium. Thus, there is a possibility of creation of the laser techniques of new generation with the parameters providing its application in pulse power engineering of the future.

Possible new interstellar masers

1980 ◽  
Vol 373 (1753) ◽  
pp. 269-284 ◽  
Keyword(s):  
Population Inversion ◽  
Diatomic Molecules ◽  
Energy Levels ◽  
Rotational Energy ◽  
Stimulated Emission

A collisional mechanism for the production of population inversion in the Λ -doublet sub-levels of the lowest rotational energy levels of diatomic molecules is considered. This leads to the conclusion that not only should the known celestial masers, OH and CH, be capable of exhibiting stimulated emission, but also H F + , HC1 + and SH.

scholarly journals POPULATION INVERSION OF ENERGY LEVELS OF MgXI 1s3p AND 1s4p UNDER THE CONDITION OF AVERAGE HIGH TEMPERATURE AND HIGH ELECTRON DENSITY

1988 ◽  
Vol 37 (8) ◽  
pp. 1236
Author(s):  
LIN ZUN-QI ◽  
CHEN WEN-HUA ◽  
YU WEN-YAN ◽  
TAN WEI-HAN ◽  
ZHENG YU-XIA ◽  
...  
Keyword(s):  
High Temperature ◽  
Electron Density ◽  
Population Inversion ◽  
Energy Levels ◽  
High Electron ◽  
High Electron Density

scholarly journals Ways to discharge-based soft X-ray lasers with the wavelength λ<15 nm

2008 ◽  
Vol 26 (2) ◽  
pp. 167-178 ◽  
Author(s):  
K. Kolacek ◽  
J. Schmidt ◽  
V. Prukner ◽  
O. Frolov ◽  
J. Straus
Keyword(s):  
Spontaneous Emission ◽  
Population Inversion ◽  
Energy Levels ◽  
Metal Vapor ◽  
Lasing Wavelength ◽  
X Ray ◽  
Metal Vapors ◽  
Collisional Recombination ◽  
Metal Vapor Plasma ◽  
Local Water

AbstractTwo basic ways to amplification of spontaneous emission in the soft X-ray region are described. The first is based on the electron-collisional recombination pumping scheme, which uses recombination of fully stripped ions into hydrogen-like ions to create (in the case of sufficiently fast cooling) a population inversion on energy levels belonging to the Balmer-alpha transition. We test this scheme on nitrogen, for which the lasing wavelength is 13.4 nm. The second way to amplification of spontaneous emission is based on the electron-collisional excitation pumping scheme: this uses for creation of population inversion a fast excitation of Ne- or Ni-like ions. However, for wavelength below 15 nm it is necessary to use Ni-like ions of some metal vapors. Feeding metal vapors into a capillary is difficult, and if being fed they deposit on the capillary wall and significantly reduce the capillary lifetime. That is why we prepare metal vapor plasma in a capillary with liquid wall – by wire explosion in water. For slowdown of the plasma-channel expansion a local-water-compression by linearly focused shock wave is being developed.

Population inversion of the energy levels of erbium ions induced by excitation transfer from the semiconductor matrix in Si-Ge based structures

JETP Letters ◽  
2005 ◽  
Vol 81 (10) ◽  
pp. 494-497 ◽  
Author(s):  
M. V. Stepikhova ◽  
D. M. Zhigunov ◽  
V. G. Shengurov ◽  
V. Yu. Timoshenko ◽  
L. V. Krasil’nikova ◽  
...  
Keyword(s):  
Population Inversion ◽  
Energy Levels ◽  
Excitation Transfer ◽  
Erbium Ions ◽  
Semiconductor Matrix

scholarly journals Saturation in the principal (excited) channel of four-level medium as an effective two-level configuration

2021 ◽  
Vol 51 (2) ◽  
Author(s):  
Jihad S. Addasi
Keyword(s):  
Energy Levels ◽  
Total Probability ◽  
Nonlinear Processes ◽  
Effective Population ◽  
Complex Molecules ◽  
Excited Triplet ◽  
Channel Ratio ◽  
Saturation Intensity ◽  
Effective Level ◽  
Level Medium

Saturation of complex molecules affects the nonlinear processes occurring in the medium. The medium can be described by two-, three-, and four-level configurations. The principal singlet-singlet and excited triplet-triplet channels of a four-level, N-type, configuration were used to study a nonlinear medium, which was excited by radiation with two frequencies. Under weak population of energy levels in the triplet-triplet channel (a small ratio of the total probability of spontaneous and irradiate transitions for both channels p23/p31), the principal (singlet-singlet) channel is similar to a two-level configuration. At the same time, the effective population of the energy levels in the triplet-triplet channel (the ratio p23/p31 is large and the radiation intensity in the principal channel is high) makes the excited (triplet-triplet) channel coincide with the two-level configuration. The saturation intensity of radiation in principal (excited) channel, as effective two-level configuration, and nonlinear processes in this channel can be controlled by external radiation acting on excited (principal) channel. Finally, the average excitation of molecules into the energy levels in the triplet-triplet channel (ratio p23/p31 ≈ 1) makes the four-level configuration similar to the three-level configuration with effective level as a result of combination between second singlet level S2 and first triplet level T1.

scholarly journals Асимметричная генерация в сверхизлучающем лазере с симметричным низкодобротным резонатором

2019 ◽  
Vol 53 (10) ◽  
pp. 1321
Author(s):  
Вл.В. Кочаровский ◽  
В.А. Кукушкин ◽  
С.В. Тарасов ◽  
Е.Р. Кочаровская ◽  
В.В. Кочаровский
Keyword(s):  
Active Medium ◽  
Population Inversion ◽  
Energy Levels ◽  
Active Centers ◽  
One Dimensional ◽  
Half Wavelength ◽  
Propagating Waves ◽  
Symmetric Cavity ◽  
Level Model ◽  
Two Level Model

On the basis of numerical solution to the Maxwell-Bloch equations within an one-dimensional two-level model of a superradiant laser with a symmetric cavity where a photon lifetime is less than an incoherent relaxation time of the optical dipole oscillations of active centers, we find that a spontaneous asymmetric generation of the counter-propagating waves is possible under a continuous homogeneous pumping of an active medium. We show that such a phenomenon of a symmetry breaking of the spatial profiles of the counter-propagating waves of an electromagnetic field as well as the polarization and population inversion of an active medium in the considered case of a weak inhomogeneous broadening of an operating transition is caused by an asymmetric half-wavelength nonlinear grating of the population inversion of the transition’s energy levels which is produced by these waves.

scholarly journals Theory of Astronomical Masers

1988 ◽  
Vol 129 ◽  
pp. 223-230
Author(s):  
Nikolaos D. Kylafis
Keyword(s):  
Energy Level ◽  
Population Inversion ◽  
Energy Levels ◽  
Level Structure ◽  
Level System ◽  
Energy Level Structure ◽  
Single Pass ◽  
Basic Concepts ◽  
Efficient Mechanisms ◽  
Exact Energy

The theory of astronomical masers is reviewed. As with laboratory masers, masing occurs when a transition between two energy levels of a molecule exhibits inverted populations. In order to present the basic concepts about masers, an idealized two-level system is used. The exact energy level structure is taken into account later on when the pumping of specific molecules is discussed. Unlike laboratory masers, where the radiation must be bounced between two mirrors to accumulate gain, the propagation of radiation in astronomical masers is a lot simpler. This is because astronomical masers are single-pass and broadband. Thus, the main theoretical effort has concentrated on inventing efficient mechanisms that produce population inversion. Specific pumping mechanisms for the three molecules (H2O, SiO, and OH) that exhibit strong masing are presented and their ability to explain the observations is discussed.

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