Cyclotron resonance in copper by a calorimetric method

1967 ◽  
Vol 296 (1447) ◽  
pp. 476-497 ◽  
Keyword(s):  
Magnetic Field ◽  
Cyclotron Resonance ◽  
Skin Depth ◽  
Negative Magnetoresistance ◽  
Calorimetric Method ◽  
Substitution Method ◽  
Resonant Orbits ◽  
Retardation Effects ◽  
The Magnetic Field

Azbel’-Kaner cyclotron resonance in copper at 136 Gc/s has been observed by a calorimetric method. Masses are presented with the magnetic field lying in a (112) plane and tipping effects investigated with the magnetic field along a <111> direction. Beyond a certain tip angle, the absorption exhibits a pronounced ‘negative magnetoresistance’ due to the removal of non­-stationary resonant orbits by tipping from the skin depth, and at smaller tip angles the resonant minima shift to lower fields as expected. The spectrometer was calibrated by a substitution method and the amplitude of the oscillations compared with theoretical estimates. Finally, a pronounced rise in absorption at low fields was observed, and arguments are presented that this is due to retardation effects.

Tipping effects in Azbel-Kaner cyclotron resonance

1967 ◽  
Vol 297 (1449) ◽  
pp. 205-229 ◽  
Keyword(s):  
Magnetic Field ◽  
Fermi Surface ◽  
Cyclotron Resonance ◽  
Skin Depth ◽  
Electron Model ◽  
Line Shapes ◽  
Parallel Polarization ◽  
Free Electron Model ◽  
Set Up ◽  
The Magnetic Field

Calculations of Azbel-Kaner line shapes when the magnetic field is tipped out of the surface have been carried out in a number of cases for both the free electron model and an arbitrary Fermi surface with mass spread. For small angles of tip the results substantiate the Doppler shift theory advanced by Koch, Stradling & Kip and provide a consistent explanation of the observed peak shifts or splitting in all cases. Arguments are presented that at larger tip angles the overall absorption will decrease with increasing field, and the original resonance may become inverted, owing to the removal of non-stationary electrons from the skin depth. At large tip angles (5° or so) inverted and doubled resonances observed with parallel polarization are shown to arise from ‘field splashes’ set up by drifting electrons from the limiting points, regardless of the nature of the Fermi surface. Apparently normal resonances observed at very large tip angles are shown to arise from so-called ‘cylinder sections’ where d A /dk 2 H = 0 and v D = 0, A and v D being the area of the orbit in k space and the drift velocity respectively.

Dependence of the a-Si:H Defect Density of States on the Magnetic Field Profile of an Electron Cyclotron Resonance Microwave Plasma

1992 ◽  
Vol 258 ◽  
Author(s):  
F.S. Pool ◽  
J.M. Essick ◽  
Y.H. Shing ◽  
R.T. Mather
Keyword(s):  
Magnetic Field ◽  
Density Of States ◽  
Cyclotron Resonance ◽  
Electron Cyclotron Resonance ◽  
Microwave Plasma ◽  
Defect Density ◽  
Electron Cyclotron ◽  
Field Profile ◽  
Magnetic Field Profile ◽  
The Magnetic Field

ABSTRACTThe magnetic field profile of an electron cyclotron resonance (ECR) microwave plasma was systematically altered to determine subsequent effects on a-Si:H film quality. Films of a-Si:H were deposited at pressures of 0.7 mTorr and 5 mTorr with a H2/SiH4 ratio of approximately three. The mobility gap density of states ND, deposition rate and light to dark conductivity were determined for the a-Si:H films. This data was correlated to the magnetic field profile of the plasma, which was characterized by Langmuir probe measurements of the ion current density. By variation of the magnetic field profile ND could be altered by more than an order of magnitude, from 1×1016 to 1×1017 at 0.7 mTorr and 1×1016 to 5×1017 at 5 mTorr. Two deposition regimes were found to occur for the conditions of this study. Highly divergent magnetic fields resulted in poor quality a-Si:H, while for magnetic field profiles defining a more highly confined plasma, the a-Si:H was of device quality and relatively independent of the magnetic field configuration.

scholarly journals On annihilation of the relativistic electron vortex pair in collisionless plasmas

2018 ◽  
Vol 84 (6) ◽  
Author(s):  
K. V. Lezhnin ◽  
F. F. Kamenets ◽  
T. Zh. Esirkepov ◽  
S. V. Bulanov
Keyword(s):  
Magnetic Field ◽  
Collisionless Plasma ◽  
Vortex Formation ◽  
Vortex Pair ◽  
Skin Depth ◽  
Secondary Vortex ◽  
Vortex System ◽  
Collisionless Plasmas ◽  
Secondary Vortices ◽  
The Magnetic Field

In contrast to hydrodynamic vortices, vortices in a plasma contain an electric current circulating around the centre of the vortex, which generates a magnetic field localized inside. Using computer simulations, we demonstrate that the magnetic field associated with the vortex gives rise to a mechanism of dissipation of the vortex pair in a collisionless plasma, leading to fast annihilation of the magnetic field with its energy transforming into the energy of fast electrons, secondary vortices and plasma waves. Two major contributors to the energy damping of a double vortex system, namely, magnetic field annihilation and secondary vortex formation, are regulated by the size of the vortex with respect to the electron skin depth, which scales with the electron$\unicode[STIX]{x1D6FE}$factor,$\unicode[STIX]{x1D6FE}_{e}$, as$R/d_{e}\propto \unicode[STIX]{x1D6FE}_{e}^{1/2}$. Magnetic field annihilation appears to be dominant in mildly relativistic vortices, while for the ultrarelativistic case, secondary vortex formation is the main channel for damping of the initial double vortex system.

Negative magnetoresistance of polymer nanocomposites on the basis of PP + Fe3O4 and PVDF + Fe3O4 in the magnetic field

2018 ◽  
Vol 537 (1) ◽  
pp. 191-197 ◽  
Author(s):  
M. A. Ramazanov ◽  
A. M. Maharramov ◽  
Luca Di Palma ◽  
H. A. Shirinova ◽  
F. V. Hajiyeva ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Polymer Nanocomposites ◽  
Negative Magnetoresistance ◽  
The Magnetic Field

THE MILLIMETRE-WAVE MAGNETO-OPTICAL RESPONSE OF Sr2RuO4

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3238-3243
Author(s):  
A. ARDAVAN ◽  
E. RZEPNIEWSKI ◽  
R. S. EDWARDS ◽  
J. SINGLETON ◽  
Y. MAENO
Keyword(s):  
Magnetic Field ◽  
Fermi Surface ◽  
Effective Mass ◽  
Cyclotron Resonance ◽  
P Wave ◽  
Harmonic Series ◽  
Millimetre Wave ◽  
The Magnetic Field ◽  
Component Parallel ◽  
Absorption Mode

We report a study of the angle-dependent millimetre-wave magnetoconductivity of the p-wave triplet-paired perovskite superconductor Sr 2 RuO 4. We find two harmonic series. We assign the first to interlayer cyclotron resonance of the β-Fermi surface and its harmonics, yielding a cyclotron effective mass of [Formula: see text]. We assign the second series, which contains only odd harmonics, to cyclotron resonance of the γ-Fermi surface, yielding a cyclotron effective mass of [Formula: see text]. In addition, we find a very strong absorption mode in the presence of a magnetic field component parallel to the quasi-two-dimensional (Q2D) planes of the sample. Its dependence on the orientation of the magnetic field cannot be described in the context of conventional Q2D cyclotron resonance, and the origin of this mode is not yet clear.

Cyclotron resonance in the extreme anomalous relaxation region

1964 ◽  
Vol 278 (1373) ◽  
pp. 256-273 ◽  
Keyword(s):  
Magnetic Field ◽  
Electron Scattering ◽  
Cyclotron Resonance ◽  
Surface Resistance ◽  
Electron Gas ◽  
Degenerate Semiconductors ◽  
Line Shapes ◽  
Infra Red ◽  
Anomalous Relaxation ◽  
The Magnetic Field

A reformulation of the theory of cyclotron resonance in metals as a variational problem is combined with the exact solution of the Boltzmann equation and used to calculate the surface resistance of an isotropic electron gas, in the extremeanom alous relaxation region, as a function of an applied magnetic field parallel to the surface of the medium . The line shapes obtained depend strongly on the diffuse or specular nature of the electron scattering a t the surface and also on the longitudinal or transverse orientation of the magnetic field relative to the current. The effect should be observable in degenerate semiconductors and semimetals a t infra-red frequencies.

DEPHASING IN PRESENCE OF A MAGNETIC FIELD

2007 ◽  
Vol 06 (03n04) ◽  
pp. 261-264 ◽  
Author(s):  
A. V. GERMANENKO ◽  
V. A. LARIONOVA ◽  
I. V. GORNYI ◽  
G. M. MINKOV
Keyword(s):  
Magnetic Field ◽  
Relaxation Time ◽  
Relaxation Rate ◽  
Negative Magnetoresistance ◽  
Phase Relaxation ◽  
Quasi Momentum ◽  
Fitting Procedure ◽  
Electron Interference ◽  
Momentum Relaxation ◽  
The Magnetic Field

Effect of the magnetic field on the rate of phase breaking is studied. It is shown that the magnetic field resulting in the decrease of phase relaxation rate [Formula: see text] makes the negative magnetoresistance due to suppression of the electron interference to be smoother in shape and lower in magnitude than that found with constant [Formula: see text]-value. Nevertheless our analysis shows that experimental magnetoconductance curves can be well fitted by the Hikami–Larkin–Nagaoka expression.1 The fitting procedure gives the value of τ/τϕ, where τ is the quasi-momentum relaxation time, which is close to the value of τ/τϕ(B = 0) with an accuracy of 25% or better when the temperature varies within the range from 0.4 to 10 K. The value of the prefactor α found from this procedure lies within the interval 0.9–1.2.

scholarly journals Ускорение электронов E-=SUB=-0n-=/SUB=--волной в круглом волноводе в режиме циклотронного резонанса

2020 ◽  
Vol 90 (6) ◽  
pp. 1022
Author(s):  
В.Н. Пашенцев ◽  
М.В. Пашенцева
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Cross Section ◽  
Cyclotron Resonance ◽  
State University ◽  
Spiral Trajectory ◽  
Synchronous Rotation ◽  
E Mail ◽  
Moscow State University ◽  
The Magnetic Field

Pashentsev V.N.1, Pashentseva M.V.2 1 National Research Nuclear University MEPhI 115409 Moscow, Russia 2 Lomonosov Moscow State University 119991 Moscow, Russia e-mail: [email protected] A method for accelerating electrons in a smooth cylindrical waveguide placed in the magnetic field of a solenoid is proposed. The motion of electrons in the waveguide occurs along a spiral trajectory shifted from the center of the waveguide. Electrons are accelerated at the cyclotron resonance frequency by the E01 or E02 waves in the direction of the waveguide axis. It is shown that the acceleration occurs as a result of synchronous rotation of particles in the cross section of the waveguide and the movement of the wave along the waveguide axis. When the electric field is maximum and has an decelerating direction, the electrons are in the center of the waveguide. Through the half-period, the direction of the electric field in the center will be braking, so under the influence of the magnetic field, the electrons rotate to the wall of the waveguide in the region of a smaller value of the decelerating electric field. It is shown that during the period of rotation of electrons the total effect of interaction of electrons with a wave is accelerating. The parameters of the accelerator for the energy of 10 MeV are estimated.

scholarly journals Alfvén wave interaction with inhomogeneous plasmas: acceleration and energy cascade towards small-scales

2004 ◽  
Vol 22 (6) ◽  
pp. 2081-2096 ◽  
Author(s):  
V. Génot ◽  
P. Louarn ◽  
F. Mottez
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Waves ◽  
Wave Interaction ◽  
Skin Depth ◽  
Alfven Wave ◽  
Double Layers ◽  
Larmor Radius ◽  
Density Gradients ◽  
Particle In Cell ◽  
The Magnetic Field

Abstract. Investigating the process of electron acceleration in auroral regions, we present a study of the temporal evolution of the interaction of Alfvén waves (AW) with a plasma inhomogeneous in a direction transverse to the static magnetic field. This type of inhomogeneity is typical of the density cavities extended along the magnetic field in auroral acceleration regions. We use self-consistent Particle In Cell (PIC) simulations which are able to reproduce the full nonlinear evolution of the electromagnetic waves, as well as the trajectories of ions and electrons in phase space. Physical processes are studied down to the ion Larmor radius and electron skin depth scales. We show that the AW propagation on sharp density gradients leads to the formation of a significant parallel (to the magnetic field) electric field (E-field). It results from an electric charge separation generated on the density gradients by the polarization drift associated with the time varying AW E-field. Its amplitude may reach a few percents of the AW E-field. This parallel component accelerates electrons up to keV energies over a distance of a few hundred Debye lengths, and induces the formation of electron beams. These beams trigger electrostatic plasma instabilities which evolve toward the formation of nonlinear electrostatic structures (identified as electron holes and double layers). When the electrostatic turbulence is fully developed we show that it reduces the further wave/particle exchange. This sequence of mechanisms is analyzed with the program WHAMP, to identify the instabilities at work and wavelet analysis techniques are used to characterize the regime of energy conversions (from electromagnetic to electrostatic structures, from large to small length scales). This study elucidates a possible scenario to account for the particle acceleration and the wave dissipation in inhomogeneous plasmas. It would consist of successive phases of acceleration along the magnetic field, the development of an electrostatic turbulence, the thermalization and the heating of the plasma. Space plasma physics (charged particle motion and acceleration; numerical studies).

Erklärung stellarer und planetarer Magnetfelder durch einen turbulenzbedingten Dynamomechanismus

1966 ◽  
Vol 21 (8) ◽  
pp. 1285-1296 ◽  
Author(s):  
M. Steenbeck ◽  
F. Krause
Keyword(s):  
Magnetic Field ◽  
Angular Velocity ◽  
Magnetic Fields ◽  
Cross Product ◽  
Skin Depth ◽  
Electrically Conducting ◽  
Magnetic Stars ◽  
The Magnetic Field ◽  
Component Parallel ◽  
Good Agreement

In a foregoing paper 1 the effects of a turbulent motion on magnetic fields were investigated. Especially turbulence was treated under the influence of CORIOLiS-forces and gradients of density and/or turbulence intensity. It was shown that on these conditions the average cross-product of velocity and magnetic field has a non-vanishing component parallel to the average magnetic field. Here we give the consequences of this effect for rotating, electrically conducting spheres.At first a sphere rotating with constant angular velocity is investigated. The quadratic effect provides for dynamo maintainance of the magnetic fields. A field of dipol-type has the weakest condition for maintainance. Applications to the magnetic field of the earth show a good agreement with the conceptions of the physical state of the earth’s core.For a second model differential rotation is included. We have also dynamo maintainance. Since we have to assume that generally the angular velocity is a function decreasing with the distance from the centre of the sphere, the calculations show that we have a preferred self-excited build-up of a quadrupol-type field. This model may be applicable to magnetic stars.Finally we look for dynamo maintainance of alternating fields. We consider the skin-depth to be small compared with the radius of the sphere, then we have plane geometry. The existence of periodical solutions is proved. Applications to the general magnetic field of the sun, which has a period of 22 years, are discussed.

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