A Superconducting Electron Speed Filter for Establishing High DC Voltages

1985 ◽  
Vol IM-34 (2) ◽  
pp. 227-231 ◽  
Author(s):  
Wolfgang Lucas ◽  
K. Schon ◽  
J. H. Hinken
Keyword(s):  
Electron Speed

VERY LONG DECAY TIME FOR ELECTRON VELOCITY DISTRIBUTION IN SEMICONDUCTORS, AND CONSEQUENT 1/f NOISE

2007 ◽  
Vol 07 (03) ◽  
pp. L193-L207 ◽  
Author(s):  
GIANCARLO CAVALLERI ◽  
ERNESTO TONNI ◽  
LEONARDO BOSI ◽  
GIANFRANCO SPAVIERI
Keyword(s):  
Planck Equation ◽  
Zero Point ◽  
Small Sample ◽  
Electron Velocity ◽  
Electron Velocity Distribution ◽  
Stochastic Electrodynamics ◽  
Power Spectral ◽  
Electron Speed ◽  
Point Field ◽  
The One

The Boltzmann equation with electron-electron (e − e) interactions has been reduced to a Fokker-Planck equation (e − e FP ) in a previuos paper. In steady-state conditions, its solution q0(v) (where v is the electron speed) depends on the square of the acceleration a = eE/m. If we introduce the nonrenormalized zero-point field (ZPF) of QED, i.e., the one considered in stochastic electrodynamics, so that [Formula: see text], then q0(v) becomes similar to the Fermi-Dirac equation, and the two collision frequencies ν1(v) and ν2(v) appearing in the e − e FP become both proportional to 1/v in a small δv interval. The condition ν1(v) ∝ ν2(v) ∝ 1/v is at the threshold of the runaways. In the same δv range, the time-dependent solution q0(v,τ) of the e − e FP decays no longer exponentially but according to a power law ∝ τ− ɛ where 0.004 < ɛ < 0.006, until τ → ∞. That extremely long memory of a fluctuation implies the same dependence τ − ɛ for the conductance correlation function, hence a corresponding power-spectral noise S(f) ∝ fɛ−1 where f is the frequency. That behaviour is maintained even for a small sample because the back diffusion velocity of the electrons in the effective range δv, where they are in runaway conditions, is much larger than the drift velocity.

Energy Band Gap Modification of Graphene Deposited on a Multilayer Hexagonal Boron Nitride Substrate

2012 ◽  
Vol 1407 ◽  
Author(s):  
Celal Yelgel ◽  
Gyaneshwar P. Srivastava
Keyword(s):  
Boron Nitride ◽  
Band Gap ◽  
Energy Band ◽  
Density Functional ◽  
Hexagonal Boron Nitride ◽  
Monolayer Graphene ◽  
Stable Configuration ◽  
Equilibrium Geometry ◽  
Energy Band Gap ◽  
Electron Speed

ABSTRACTThe equilibrium geometry and electronic structure of graphene deposited on a multilayer hexagonal boron nitride (h-BN) substrate has been investigated using the density functional and pseudopotential theories. We found that the energy band gap for the interface between a monolayer graphene (MLG) and a monolayer BN (MLBN) lies between 47 and 62 meV, depending on the relative orientations of the layers. In the most energetically stable configuration the binding energy is found to be approximately 40 meV per C atom. Slightly away from the Dirac point, the dispersion curve is linear, with the electron speed almost identical to that for isolated graphene. The dispersion relation becomes reasonably quadratic for the interface between MLG and 4-layer-BN, with a relative effective mass of 0.0047. While the MLG/MLBN superlattice is metallic, the thinnest armchair nanoribbon of MLG/MLBN interface is semiconducting with a gap of 1.84 eV.

The Mobility Distribution and Rate of Formation of Negative Ions in Air

1929 ◽  
Vol 25 (2) ◽  
pp. 205-218 ◽  
Author(s):  
J. L. Hamshere
Keyword(s):  
Continuous Distribution ◽  
Negative Ions ◽  
Ionic Mobility ◽  
Field Method ◽  
Resolving Power ◽  
Free Electrons ◽  
Electron Speed ◽  
Lower Limits ◽  
Low Pressures ◽  
Peak Value

A modification of the alternating field method of measuring ionic mobility in a gas gives an experimental curve showing upper and lower limits to k. From this a distribution curve is derived, which has a calculable resolving power.The mobility of negative ions in dry air shows a continuous distribution between the limits 2·15 and 1·45, with a peak value about 1·8.At low pressures the current is resolved into ions and free electrons. From the relative numbers reaching the electrometer it is found that the electron makes an average number 9·4. 104 collisions before capture, independent of field strength and pressure, and therefore independent of the electron speed over a range W = 2×105 to W = 7×105.

Atomic and Electronic Structure of Multilayer Graphene on a Monolayer Hexagonal Boron Nitride

2013 ◽  
Vol 1549 ◽  
pp. 65-70
Author(s):  
Celal Yelgel ◽  
Gyaneshwar P. Srivastava
Keyword(s):  
Boron Nitride ◽  
Density Functional ◽  
Local Density ◽  
Hexagonal Boron Nitride ◽  
Binding Energies ◽  
Multilayer Graphene ◽  
Functional Theory ◽  
Electron Speed ◽  
The Density Functional Theory ◽  
Trilayer Graphene

ABSTRACTThe atomic and electronic structures of multilayer graphene on a monolayer boron nitride (MLBN) have been investigated by using the pseudopotential method and the local density approximation (LDA) of the density functional theory (DFT). We show that the LDA energy band gap can be tuned in the range 41-278 meV for a multilayer graphene by using MLBN as a substrate. The dispersion of the π/π* bands slightly away from the K point is linear with the electron speed of 0.9×106 and 0.93×106 for graphene (MLG)/MLBN and ABA trilayer graphene (TLG)/MLBN systems, respectively. This behaviour becomes quadratic with a relative effective mass of 0.0021 for the bilayer graphene (BLG)/MLBN system. The calculated binding energies are in the range of 10-43 meV per C atom.

On ion—electron beams emitted by a plane

1967 ◽  
Vol 1 (3) ◽  
pp. 267-288
Author(s):  
Yeshaiahu Y. Winograd
Keyword(s):  
Steady State ◽  
Speed Of Sound ◽  
Sound Speed ◽  
Ion Beam ◽  
Debye Length ◽  
Maximum Velocity ◽  
Plasma Sheath ◽  
Injection Velocity ◽  
Electron Speed ◽  
Ion Velocity

The non-linear one-dimensional steady-state equations which govern the flow of an ion—electron beam emitted from a plane are solved in the phase plane, and it is shown that a perfectly neutralized beam follows for a large range of injection velocities of the electrons. When the velocity of the ions is less than the electron sound speed the transition region for the neutralization has a length of the order of a Debye length λD = (kT)½ (4πNe2)–½, which is a typical plasma sheath. The maximum velocity of injection of the electrons for which neutralization is predicted is, in this case, the sound speed of the electrons. If the electrons are injected with a supersonic speed, they cannot be decelerated continuously to the subsonic speed corresponding to the velocity of the ions. No bound is set on the electron injection velocity from below. When the velocity of the ion beam is greater than the electron sound speed, oscillations with an amplitude which depends on the velocity of injection of the electrons, and a wavelength which depends on the ratio of the ion velocity to the electron speed of sound, are found. In this case the injection speed of the electrons needed to obtain the steady-state oscillatory solution is bounded both from above and from below. Subsonic electrons cannot be accelerated continuously to the supersonic velocity required to match the velocity of the ions, and within the supersonic range there is shown to be a limit (depending on the ratio of the ion velocity to the electron speed of sound, so that faster electrons cannot be decelerated continuously to match the (supersonic) ion velocity.

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