Study of Electron-Wave Microwave Amplifiers at High Values of the Inhomogeneity Parameters of the Electron Beam Velocities

2019 ◽  
Vol 62 (1) ◽  
pp. 26-32
Author(s):  
Yu. A. Kalinin ◽  
A. V. Starodubov
Keyword(s):  
Electron Beam ◽  
Electron Wave ◽  
Microwave Amplifiers

scholarly journals An electron wave packet in the relativistic strophotron FEL

2021 ◽  
Vol 19 (1) ◽  
pp. 016001
Author(s):  
K B Oganesyan ◽  
M Hnatic ◽  
P Kopchancky
Keyword(s):  
Electron Beam ◽  
Wave Packet ◽  
Initial Distribution ◽  
Quantum Mechanical ◽  
Initial Moment ◽  
Electron Wave ◽  
Electron Wave Packet ◽  
Vibrational Levels ◽  
Mechanical Approach ◽  
Quantum Mechanical Approach

Abstract The theory of free electron lasers (FELs) is well developed both in quantum mechanical and classical approaches. In strophotron FEL, in classical approach, resonance frequency and the gain are strongly dependent on initial parameters of electron beam. In the quantum mechanical approach considered by Zaretsky and Nersesov (1983 JETP 57 518), there is no such dependence. The correspondence between the quantum mechanical and classical approaches in a relativistic strophotron FEL is discussed. We study the initial distribution of electrons over vibrational levels determined by the expansion coefficients in relativistic strophotron FEL. It is shown, (presenting electron wave function in the form of Gaussian wave packet), that the number of the vibrational level most efficiently populated at the initial moment of time can be expressed in terms of the initial parameters of the electron beam.

scholarly journals Spectral DQE of the Volta Phase Plate

2020 ◽  
Author(s):  
Bart Buijsse ◽  
Piet Trompenaars ◽  
Veli Altin ◽  
Radostin Danev ◽  
Robert M. Glaeser
Keyword(s):  
Thin Film ◽  
Electron Beam ◽  
Surface Potential ◽  
Carbon Films ◽  
Phase Plate ◽  
Electron Wave ◽  
Weak Phase ◽  
Spatial Frequencies ◽  
Altered Surface ◽  
Phase Plates

ABSTRACTThe Volta Phase Plate (VPP) consists of a heated, thin film that is placed in the same plane as the focused diffraction pattern of an electron microscope. A change in surface potential develops at the point irradiated by the intense, unscattered electron beam, and this altered surface potential produces, in turn, a phase shift between the unscattered and scattered parts of the electron wave. While the VPP thus increases the image contrast for weak-phase objects at low spatial frequencies, we report here that it also leads to the loss of an increasing fraction of the signal at higher resolution. The approximately linear dependence (with increasing resolution) of this loss has been quantified at 200 kV and 300 kV, using evaporated-carbon films of different thicknesses as Volta phase plates. In all cases, the loss of signal remains almost independent of variation of the conditions and parameters that were tested. In spite of having done a number or additional, discovery-based experiments, the cause of this loss of signal remains unexplained at this point.

Demonstration of Arrays of Sub-Micrometer Solid-State Fresnel Lenses for Electrons

2000 ◽  
Vol 636 ◽  
Author(s):  
Y. Ito ◽  
A. L. Bleloch ◽  
L. M. Brown
Keyword(s):  
Electron Beam ◽  
Solid State ◽  
Electron Beam Lithography ◽  
Full Width Half Maximum ◽  
Focal Point ◽  
Focal Length ◽  
Full Width ◽  
Electron Wave ◽  
X Ray ◽  
Fresnel Lenses

AbstractWe demonstrate the focusing action of a compact solid state pixelated Fresnel phase (PFP) lens for electrons (700 nm in diameter), consisting of an array of holes (“pixelated”) directly drilled by a finely focused electron beam in a thin AlF3 thin film on carbon supporting film. The depths of holes, hence the phase of the exit electron wave is varied as a function of radius from the center of the pattern so that the wavelet from each hole can be in phase on axis at a designated focal point thus producing a lens. An array of two types of lenses, convergent and divergent, with nominal focal length of 1 mm for 200 keV electrons was produced. The estimated full-width-half-maximum of the focus is 8 nm. With improvement of the efficiency, these lenses may find applications in parallel electron-beam lithography, in X-ray optics and in light optics.

scholarly journals Умеренно релятивистский генератор микроволнового излучения субгигаваттного уровня типа твистрон с эффективностью 50%

2019 ◽  
Vol 45 (6) ◽  
pp. 47
Author(s):  
Е.М. Тотьменинов ◽  
С.А. Кицанов ◽  
А.И. Климов ◽  
А.Н. Синяков
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Power Conversion ◽  
Wave Interaction ◽  
Beam Current ◽  
Beam Power ◽  
Electron Wave ◽  
Microwave Generation ◽  
Beam Parameters ◽  
Diode Voltage

AbstractA regime of quasi-stationary microwave generation in moderately relativistic microwave oscillator of the twistron type with 50 ± 20% efficiency of electron beam power conversion into electromagnetic radiation has been obtained in experiment through optimization of the electron–wave interaction. For the selected electron beam parameters (diode voltage, 210 kV; beam current. 1.36 kA) the output microwave power at 10.63 GHz frequency was 140 ± 40 MW in a guiding magnetic field of about 1.9 T. The duration of microwave pulses was about 16 ns.

scholarly journals Electron polarisation

1932 ◽  
Vol 136 (830) ◽  
pp. 558-568 ◽  
Keyword(s):  
Electron Beam ◽  
Wave Equation ◽  
Intensity Distribution ◽  
Electromagnetic Waves ◽  
X Rays ◽  
Double Scattering ◽  
Electron Wave ◽  
Observable Effect ◽  
Scattering Experiment ◽  
Secondary Scattering

Dirac’s modified wave equation which successfully accounts for many of the phenomena interpreted as due to the spin of orbital electrons, also predicts that the free electron should have a spin. On this basis each electron wave is characterised by a definite direction other than that of propagation, and an electron beam should be capable of exhibiting polarisation. A method for the production and detection of a polarised electron beam is suggested by the double scattering experiments for the production and detection of polarised X-rays, especially in view of the similarity between diffraction phenomena for electrons and electromagnetic waves. Double scattering experiments have been performed by a number of investi­gators and it has been well established that no observable effect is found with electrons having energies in the neighbourhood of 100 volts.* With very much higher energies, however, an asymmetry in the intensity distribution of the secondary scattering appears to exist, although the evidence is somewhat contradictory and incomplete. This paper gives an account of a double scattering experiment in which electrons were successively reflected at approxi­mately 90° from thick polycrystalline tungsten targets. The results extend the region in which the asymmetry in the secondary scattering is known to be less than 1 per cent, to electron energies of 10 kilovolts.

scholarly journals Variable Magnification Electron Holography for 2-D Mapping of Semiconductor Devices

2004 ◽  
Vol 12 (6) ◽  
pp. 20-25
Author(s):  
Y.Y. Wang ◽  
M. Gribelyuk ◽  
A. Domenicucci ◽  
J. Bruley ◽  
J. Gaudiello ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Spherical Aberration ◽  
Ccd Camera ◽  
Electron Holography ◽  
Electron Wave Function ◽  
Phase Information ◽  
Electron Wave ◽  
Scattered Electron ◽  
Transmission Electron

The exit electron wave from transmission electron microscopy (TEM) specimens contains both amplitude and phase information. In routine TEM imaging, only amplitude information is recorded on the recording devices (film or CCD camera) and phase information of the electron wave function normally is canceled out.In 1947, Dennis Gabor proposed off-axis electron holography, a method of interference imaging in which the phase and amplitude components of the electron beam are obtained to correct spherical aberration of the transmission electron microscope to improve spatial resolution. In that process, the electron beam is split into the two beams: the un-scattered electron beam (i.e. the reference wave) and the image beam (or object wave) diffracted by the specimen and exiting the bottom of the specimen surface.

Applications of electron holography to interference microscopy

1991 ◽  
Vol 49 ◽  
pp. 676-677
Author(s):  
Akira Tonomura
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Field Emission ◽  
Phase Distribution ◽  
Phase Measurement ◽  
Interference Microscopy ◽  
Electron Holography ◽  
Electron Wave ◽  
Interference Fringes ◽  
Fluorescent Screen

Electron-holographic interference microscopy, which provides an image of the phase distribution of an electron wave transmitted through a specimen, has become practical with the development of a field-emission electron microscope. This instrument, increasing the brightness of the electron beam by more than two orders of magnitude, allows biprism interference fringes to be directly observed on a fluorescent screen. The coherence of this microscope's electron beam has enabled phase measurement to a precision of 1/100 of the wavelength, and it even makes dynamical observation possible.

Differential phase contrast Lorentz microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 758-759
Author(s):  
Ian R. McFadyen
Keyword(s):  
Electron Beam ◽  
Phase Shift ◽  
Magnetic Induction ◽  
Phase Contrast ◽  
Magnetic Films ◽  
Electron Wave ◽  
Lorentz Microscopy ◽  
Differential Phase ◽  
Phase Derivative ◽  
Differential Phase Contrast

Transmission electron microscopy can provide high spatial resolution information on domain structures in thin magnetic films provided the interaction between the electron beam and the magnetic sample is correctly utilised: As an electron beam passes through a magnetic sample it suffers a phase shift due to the magnetic induction of the sample and the associated stray fields. The derivative of this phase shift is a direct measure of the in-plane magnetic induction integrated along the electron trajectory, Therefore measurement of this phase derivative would provide the integrated in-plane induction directly. The conventional phase contrast techniques of Fresnel and Foucault Lorentz microscopy provide image contrast which has a very non-linear relationship to the above mentioned phase derivative. Differential phase contrast Lorentz microscopy (DPC), on the other hand, does provide direct, high resolution information on the phase derivative of the electron wave as it leaves tile sample. In this technique a focused probe of electrons is scanned cross the sample and a position sensitive detector in the far field measures two orthogonal components of the probe deflection angle at each point in the scan. This corresponds to the derivative of the phase of the electron wave as it leaves the sample, and thus to the integral of the in-plane induction at each point.

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