The research of laser crystal length impact on the self-Raman dual-wave length lasers output characteristics

Plasma-based accelerators sustain accelerating gradients which are several orders greater than obtained in conventional accelerators. Focusing of electron and positron beams by wakefield, excited in plasma, in electron-positron collider is very important. The focusing mechanism in the plasma, in which all electron bunches of a sequence are focused identically, has been proposed by authors earlier. The mechanism of focusing of a sequence of relativistic positron bunches in plasma, in which all positron bunches of sequence are focused identically and uniformly, has been investigated in this paper by numerical simulation by 2.5D code LCODE. Mechanism of this identical and uniform focusing involves the use of wave-length λ, which coinciding with double longitudinal dimension of bunches λ=2Db, the first bunch current is in two times smaller than the current of the following bunches of sequence and the distance between bunches equals to one and a half of wavelength 1.5λ. We numerically simulate the self-consistent radial dynamics of lengthy positron bunches in homogeneous plasma. In simulation we use the hydrodynamic description of plasma. In other words the plasma is considered to be cold electron liquid, and positron bunches are aggregate of macroparticles. Positron bunches are considered to be homogeneous cylinders in the longitudinal direction. Positrons in bunches are distributed in radial direction according to Gaussian distribution. It is shown that in this case only first bunch is in the finite longitudinal electrical wakefield Ez¹0. Other bunches are in zero longitudinal electrical wakefield Ez=0. Between bunches of this sequence longitudinal electrical wakefield and radial force are not zero Ez¹0, Fr¹0. The focusing radial force in regions, occupied by bunches, is constant along each bunch Fr=const. Between bunches the radial force is inhomogeneous Fr¹const. All positron bunches of sequence are focused identically and uniformly.

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Self-dual formulation of gravity in topological M-theory

International Journal of Geometric Methods in Modern Physics ◽

10.1142/s0219887820500474 ◽

2020 ◽

Vol 17 (03) ◽

pp. 2050047

Author(s):

Andrea Addazi ◽

Antonino Marciano

Keyword(s):

Quantum Gravity ◽

Loop Quantum Gravity ◽

Wave Length ◽

The Self ◽

Hamiltonian Constraint ◽

Flat Connection ◽

Line Defect ◽

Dual Formulation ◽

Dual Variables ◽

M Theory

Inspired by the low wave-length limit of topological M-theory, which re-constructs the theory of 3 + 1D gravity in the self-dual variables’ formulation, and by the realization that in Loop Quantum Gravity (LQG) the holonomy of a flat connection can be non-trivial if and only if a non-trivial (space-like) line defect is localized inside the loop, we argue that non-trivial gravitational holonomies can be put in correspondence with space-like M-branes. This suggests the existence of a new duality, which we call [Formula: see text] duality, interconnecting topological M-theory with LQG. We spell some arguments to show that fundamental S-strings are serious candidates to be considered in order to instantiate this correspondence to classes of LQG states. In particular, we consider the case of the holonomy flowers in LQG, and show that for this type of states the action of the Hamiltonian constraint, from the M-theory side, corresponds to a linear combination of appearance and disappearance of a SNS1-strings. Consequently, these processes can be reinterpreted, respectively, as enucleations or decays into open or closed strings.

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DYNAMIC STRUCTURE FUNCTION OF QUANTUM BOSE SYSTEMS: CONDENSATE FRACTION AND MOMENTUM DISTRIBUTION

International Journal of Modern Physics B ◽

10.1142/s0217979208050085 ◽

2008 ◽

Vol 22 (25n26) ◽

pp. 4327-4337

Author(s):

M. SAARELA ◽

F. MAZZANTI ◽

V. APAJA

Keyword(s):

Structure Function ◽

Essential Feature ◽

Wave Length ◽

External Perturbation ◽

Dynamic Structure ◽

Short Wave ◽

The Self ◽

Condensate Fraction ◽

Self Energy ◽

Continuity Equations

We present results on the behavior of the dynamic structure function in the short wave length limit using the equation of motion method. Within this framework we study the linear response of a quantum system to an infinitesimal external perturbation by direct minimization of the action integral. As a result we get a set of coupled continuity equations which define the self-energy. We evaluate the self-energy and the dynamic structure function in the short wavelength limit and show that sum rules up to the third moment are fulfilled. This implies, for instance, that the self-energy at short wavelengths and zero frequency is proportional to the kinetic energy per particle. An essential feature in this derivation is that the short range behavior of the two-particle distribution and the long wavelength phonon induced scattering are exactly satisfied. We calculate the condensate fraction and show that our results agree very well with the Monte Carlo simulations.

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Piezoelectric Polaron Effects in Regular Crystals

Zeitschrift für Naturforschung A ◽

10.1515/zna-1964-1322 ◽

1964 ◽

Vol 19 (13) ◽

pp. 1591-1598 ◽

Cited By ~ 2

Author(s):

Helmut Gabriel

Keyword(s):

Effective Mass ◽

Lattice Structure ◽

Numerical Estimate ◽

Wave Length ◽

Approximate Solutions ◽

The Self ◽

Large Wave ◽

Self Energy ◽

Arbitrary Lattice ◽

Pertubation Theory

Due to the interaction of an electron with both optical and acoustical modes in piezoelectric polar crystals, modified expressions for the self-energy and effective mass of the polaron are to be expected. The lattice vibrations are considered in the limit of large wave-length and an electrostatic approach to the interaction of charges in the lattice has been used. The HAMILTONIAN for a piezoelectric crystal of arbitrary lattice structure is given. With special reference to crystals of zincblende-type, approximate solutions for the self-energy and effective mass are found by thermodynamical pertubation theory. A numerical estimate for ZnS as a particularly favourable example, shows a negligible modification of the ground-state energy, but concerning the effective mass a contribution due to acoustical phonons of more than 50% of the optical-mode term.

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Twin structure in Yb:YAl3(BO3)4crystal

Journal of Applied Crystallography ◽

10.1107/s0021889801010834 ◽

2001 ◽

Vol 34 (5) ◽

pp. 661-662 ◽

Cited By ~ 5

Author(s):

Shanrong Zhao ◽

Jiyang Wang ◽

Daliang Sun ◽

Xiaobo Hu ◽

Hong Liu

Keyword(s):

Atomic Force Microscopy ◽

Single Crystals ◽

Chemical Etching ◽

Laser Crystal ◽

Frequency Doubling ◽

Twin Plane ◽

The Self ◽

Twin Structure ◽

Force Microscopy ◽

Atomic Force

Twin structure is a defect in the self-frequency-doubling laser crystal material Yb:YAl3(BO3)4(YbYAB). Based on atomic force microscopy (AFM) observations, a check-like twin structure in YbYAB crystals is found. This kind of twin structure has three twin composition planes: (10\bar{1}1), (0\bar{1}11) and (\bar{1}101). These three twin composition planes result in a series of twin boundaries in two directions, forming a check-like pattern on each face. From the orientation of the chemical etching pits on each side of the twin boundary, it is found that the twin element is `twin plane ⊥yaxis', alternatively indicated as `twin plane {11\bar{2}0}'. The two single crystals composing the twin are a right form and a left form. This kind of twin is similar to the Brazil twin found in quartz.

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Self-Mixing Signal Characteristics of Complex-Coupled Distributed-Feedback Terahertz Quantum-Cascade Lasers

Frontiers in Physics ◽

10.3389/fphy.2021.744286 ◽

2021 ◽

Vol 9 ◽

Author(s):

Lei Ge ◽

Ning Yang ◽

Jian Wang ◽

Weidong Chu ◽

Suqing Duan ◽

...

Keyword(s):

Quantum Cascade Lasers ◽

Wave Theory ◽

Coupling Factor ◽

Distributed Feedback ◽

The Self ◽

Quantum Cascade ◽

Mode Hopping ◽

Mixing Frequency ◽

Output Characteristics ◽

Cascade Lasers

Self-mixing interference (SMI) in terahertz quantum cascade lasers (THz QCLs) is one of the significant approaches for coherent THz imaging and sensing techniques. Here, the output characteristics of SMI in distributed feedback (DFB) THz QCLs from the index-to the gain-coupling regimes are studied using the coupled wave theory and the multi-mode rate equation method. A mode hopping phenomenon is found to occur when the DFB coupling factor changes from index-coupling to gain-coupling, and the characteristics of the self-mixing signals of DFB-QCLs change greatly with this mode hopping. With the modulus of the coupling factor fixed and its argument varied from 0 to π/2, an extreme point of the self-mixing frequency and power signals of DFB-QCLs is found at π/9 due to the mode hopping. For index-coupling dominated DFB-QCLs, both the varying ranges of the self-mixing frequency signals and amplitudes of power signals increase with increasing DFB coupling factor argument. For gain-coupling dominated DFB-QCLs, with increasing argument value, the amplitude of the self-mixing power signal increases, but the varying range of the self-mixing frequency signal decreases. With the argument of the coupling factor fixed, we also found that the varying ranges of the self-mixing frequency signals decrease with increasing modulus for both index-coupling dominated and gain-coupling dominated DFB-QCLs. For index-coupling dominated DFB-QCLs, the amplitudes of the self-mixing power signals decrease with increasing modulus; however, the amplitudes of the self-mixing power signals of gain-coupling dominated DFB-QCLs increase. With the argument of the coupling factor fixed, for index-coupling dominated DFB-QCLs, we found that the varying ranges of the self-mixing frequency signals and amplitudes of power signals decrease with the increasing modulus. For gain-coupling dominated DFB-QCLs, with the coupling factor modulus increasing, the varying ranges of the self-mixing frequency signals decrease, however, the amplitudes of the self-mixing power signals increase. These results may help with the application of DFB-QCLs to self-mixing interferometers.

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ON THE THEORY OF THE X-RAY DETERMINATION OF ELASTIC SCATTERING OF CATHODE RAYS

Canadian Journal of Research ◽

10.1139/cjr34-081 ◽

1934 ◽

Vol 11 (2) ◽

pp. 156-162

Author(s):

Darol K. Froman

Keyword(s):

Wave Length ◽

Absolute Measurement ◽

Theoretical Work ◽

The Self ◽

Solid Target ◽

X Rays ◽

Scattering Function ◽

X Ray ◽

Self Consistency

This paper is a continuation of Bubb's (1) theoretical work which relates the energies and momenta of cathode rays to the properties of X-ray photons produced by them. Bubb's results are used to determine a scattering function for the cathode rays in a target in terms of the intensities of X-rays of minimum wave-length emergent from the target at various angles to the incident cathode-ray stream. It is shown that the self-consistency of Bubb's results can be tested by measurements of the intensities of two components of these X-rays polarized in mutually perpendicular planes. Mention is made of an experiment now in progress designed to test Bubb's theory by an absolute measurement using a gaseous instead of a solid target.

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Compact undulator line for a high-brilliance soft-X-ray free-electron laser at MAX IV

Journal of Synchrotron Radiation ◽

10.1107/s160057751900290x ◽

2019 ◽

Vol 26 (3) ◽

pp. 891-898

Author(s):

Alan Mak ◽

Peter Salén ◽

Vitaliy Goryashko

Keyword(s):

Parameter Space ◽

Free Electron ◽

Free Electron Laser ◽

Optimal Parameter ◽

Operation Mode ◽

The Self ◽

X Ray ◽

Short Period ◽

Recent Developments ◽

Output Characteristics

The optimal parameter space for an X-ray free-electron laser (FEL) in the self-amplified spontaneous emission (SASE) operation mode is examined. This study focuses on FEL operation with a shorter undulator period and higher undulator strength made available through recent developments in in-vacuum, cryogenic and superconducting undulators. Progress on short-period undulator technologies is surveyed and FEL output characteristics versus undulator parameters are computed. The study is performed on a case of the planned soft-X-ray FEL at the MAX IV Laboratory in Sweden. An extension of the SASE mode into the harmonic lasing self-seeded mode is also analysed.

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CONDENSATE FRACTION IN THE DYNAMIC STRUCTURE FUNCTION OF BOSE FLUIDS

International Journal of Modern Physics B ◽

10.1142/s0217979207043567 ◽

2007 ◽

Vol 21 (13n14) ◽

pp. 2169-2180

Author(s):

M. SAARELA ◽

F. MAZZANTI ◽

V. APAJA

Keyword(s):

Structure Function ◽

Wave Length ◽

Impulse Approximation ◽

Dynamic Structure ◽

Short Wave ◽

The Self ◽

Condensate Fraction ◽

Self Energy ◽

Short Wave Length ◽

The One

We present results on the behavior of the dynamic structure function in the short wave length limit using the equation of motion method. The one-body continuity equation defines the self-energy, which becomes a functional of the fluctuating two-body correlation function. We evaluate the self-energy in this limit and show that sum rules up to the second moment, which requires the self-energy in the short wave length limit and zero frequency to be proportional to the kinetic energy per particle, are exactly satisfied. We compare our results with the impulse approximation and calculate the condensate fraction. An analytic expression for the momentum distribution is also derived.

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