scholarly journals Subnanosecond breakdown of air-insulated coaxial line initiated by runaway electrons in the presence of a strong axial magnetic field

2021 ◽  
Vol 2064 (1) ◽  
pp. 012003
Author(s):  
G A Mesyats ◽  
E A Osipenko ◽  
K A Sharypov ◽  
V G Shpak ◽  
S A Shunailov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Voltage Pulse ◽  
Plasma Layer ◽  
Axial Magnetic Field ◽  
Coaxial Line ◽  
Runaway Electrons ◽  
Cathode Plasma ◽  
Fast Electrons

Abstract Flow of runaway electrons (RAEs) propagating in a radial, air-filled gap of coaxial line (CL) changes the dynamics of breakdown in the field of traveling voltage pulse. However, despite the effect of RAEs, breakdown does not occur if subnanosecond pulse is less in duration and amplitude than some values. In this work, we study the influence of an external axial magnetic field (B z) on the breakdown development. We demonstrate the transformation of the voltage pulse reflection from the ionized (breakdown) zone with changing B z. Due to gyration of fast electrons in an applied magnetic field, the gas region ionized by RAEs does not reach the anode. The ionized bridge between the cathode and anode is gradually replaced by a near-cathode plasma layer representing a discrete, reflecting/absorbing inhomogeneity in the CL.

scholarly journals Magnetically Induced Carrier Distribution in a Composite Rod of Piezoelectric Semiconductors and Piezomagnetics

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3115 ◽  
Author(s):  
Guolin Wang ◽  
Jinxi Liu ◽  
Wenjie Feng ◽  
Jiashi Yang
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Axial Magnetic Field ◽  
Semiconductor Layer ◽  
Carrier Distribution ◽  
Composite Rod ◽  
Piezoelectric Effects ◽  
Potential Applications ◽  
Piezoelectric Coupling ◽  
Piezoelectric Semiconductors

In this work, we study the behavior of a composite rod consisting of a piezoelectric semiconductor layer and two piezomagnetic layers under an applied axial magnetic field. Based on the phenomenological theories of piezoelectric semiconductors and piezomagnetics, a one-dimensional model is developed from which an analytical solution is obtained. The explicit expressions of the coupled fields and the numerical results show that an axially applied magnetic field produces extensional deformation through piezomagnetic coupling, the extension then produces polarization through piezoelectric coupling, and the polarization then causes the redistribution of mobile charges. Thus, the composite rod exhibits a coupling between the applied magnetic field and carrier distribution through combined piezomagnetic and piezoelectric effects. The results have potential applications in piezotronics when magnetic fields are relevant.

scholarly journals Emission Features and Structure of an Electron Beam versus Gas Pressure and Magnetic Field in a Cold-Cathode Coaxial Diode

Electronics ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 248
Author(s):  
Gennady Mesyats ◽  
Vladislav Rostov ◽  
Konstantin Sharypov ◽  
Valery Shpak ◽  
Sergey Shunailov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Runaway Electrons ◽  
High Current ◽  
Emission Mechanism ◽  
Explosive Emission ◽  
Fast Electrons ◽  
Atmospheric Air ◽  
Emission Surface ◽  
The Magnetic Field

The structure of the emission surface of a cold tubular cathode and electron beam was investigated as a function of the magnetic field in the coaxial diode of the high-current accelerator. The runaway mode of magnetized electrons in atmospheric air enabled registering the instantaneous structure of activated field-emission centers at the cathode edge. The region of air pressure (about 3 Torr) was determined experimentally and via analysis, where the explosive emission mechanism of the appearance of fast electrons with energies above 100 keV is replaced by the runaway electrons in a gas.

scholarly journals Transverse electromagnetic Hermite–Gaussian mode-driven direct laser acceleration of electron under the influence of axial magnetic field

2018 ◽  
Vol 36 (1) ◽  
pp. 154-161 ◽  
Author(s):  
Harjit Singh Ghotra ◽  
Dino Jaroszynski ◽  
Bernhard Ersfeld ◽  
Nareshpal Singh Saini ◽  
Samuel Yoffe ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Laser Beam ◽  
Applied Magnetic Field ◽  
Axial Magnetic Field ◽  
Energy Gain ◽  
Electron Interaction ◽  
Direct Laser ◽  
Tem Mode ◽  
Laser Acceleration ◽  
Transverse Electromagnetic

AbstractHermite–Gaussian (HG) laser beam with transverse electromagnetic (TEM) mode indices (m, n) of distinct values (0, 1), (0, 2), (0, 3), and (0, 4) has been analyzed theoretically for direct laser acceleration (DLA) of electron under the influence of an externally applied axial magnetic field. The propagation characteristics of a TEM HG beam in vacuum control the dynamics of electron during laser–electron interaction. The applied magnetic field strengthens the $\vec v \times \vec B$ force component of the fields acting on electron for the occurrence of strong betatron resonance. An axially confined enhanced acceleration is observed due to axial magnetic field. The electron energy gain is sensitive not only to mode indices of TEM HG laser beam but also to applied magnetic field. Higher energy gain in GeV range is seen with higher mode indices in the presence of applied magnetic field. The obtained results with distinct TEM modes would be helpful in the development of better table top accelerators of diverse needs.

Influence of Axial Magnetic Field on Cathode Plasma Jets in High-Current Vaccum Arc

2017 ◽  
Vol 45 (9) ◽  
pp. 2596-2603 ◽  
Author(s):  
Dingge Yang ◽  
Shenli Jia ◽  
Weidong Qi ◽  
Jingfeng Wu ◽  
Sen Wang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Axial Magnetic Field ◽  
Plasma Jets ◽  
High Current ◽  
Cathode Plasma

Segregation During Magnetically-Stabilized Liquid-Encapsulated Growth of Compound Semiconductor Crystals

2000 ◽  
Author(s):  
Nancy Ma ◽  
David F. Bliss ◽  
George G. Bryant
Keyword(s):  
Magnetic Field ◽  
Optical Properties ◽  
Applied Magnetic Field ◽  
Dopant Concentration ◽  
Axial Magnetic Field ◽  
Compound Semiconductor ◽  
Semiconductor Crystal ◽  
Semiconductor Crystals ◽  
Single Compound ◽  
Relative Motions

Abstract During the magnetically-stabilized liquid-encapsulated Czochralski (MLEC) process, a single compound semiconductor crystal is grown by the solidification of an initially molten semiconductor (melt) contained in a crucible. The melt is doped with an element in order to vary the electrical and/or optical properties of the crystal. During growth, the so-called melt-depletion flow caused by the opposing relative motions of the encapsulant-melt interface and the crystal-melt interface can be controlled with an externally applied magnetic field. The convective dopant transport during growth driven by this melt motion produces non-uniformities of the dopant concentration in both the melt and the crystal. This paper presents a model for the unsteady transport of a dopant during the MLEC process with an axial magnetic field. Dopant distributions in the crystal and in the melt at several different stages during growth are presented.

Measurement of microwave reflexion from a longitudinally magnetized plasma-filed co-axial wave-guide

1971 ◽  
Vol 5 (1) ◽  
pp. 89-105 ◽  
Author(s):  
M. L. G. Oldfield ◽  
R. N. Franklin
Keyword(s):  
Magnetic Field ◽  
Shock Tube ◽  
Microwave Plasma ◽  
Axial Magnetic Field ◽  
Initial Pressure ◽  
Coaxial Line ◽  
Plasma Boundary ◽  
Magnetized Plasma ◽  
Electron Collision ◽  
Ion Density

The voltage refiexion coefficient from a vacuum-plasma boundary in a co-axial transmission line with an axial magnetic field B0 applied has been measured. The results agree well with a previously published theory for conditions where the microwave-, plasma-, electron collision-, and electron cyclotron-frequencies are of the same order. A 9 GHz co-axial microwave probe is mounted along the axis of a 44mm diameter, hydrogen driven, dry air filled, shock tube in an axial d.c. magnetic field. Shock ionized air (Ms = 9–14, T 4000 °K, electron density nc = 1017 to 3 x 1019 m−3, initial pressure p0 = 1–10 Torr, electron collision frequency v = 1010 to 1011/S) fills the coaxial line and partially reflects a microwave signal. Initially this probe, and a similar rectangular waveguide probe, were used with B0 = 0 to calibrate the plasma (ne, v) in terms of the shock tube parameters (p0, Ms). Measurement of the saturated-ion current to electrostatic probes inset into a fiat plate in the shock tube flow showed that the sheath-edge ion density is close to the predicted free-stream equilibrium ion density. The apparent ionization potential derived from electrostatic probe results decreased as p0 was reduced from 10 to 1 Torr.

Finite deformations and incremental axisymmetric motions of a magnetoelastic tube

2017 ◽  
Vol 23 (6) ◽  
pp. 950-983 ◽  
Author(s):  
Prashant Saxena
Keyword(s):  
Magnetic Field ◽  
Internal Pressure ◽  
Applied Magnetic Field ◽  
Axial Magnetic Field ◽  
Cylindrical Tube ◽  
Axial Stretch ◽  
Mechanical Waves ◽  
Wave Guides ◽  
The Stability ◽  
Circular Cylindrical Tube

A thick-walled circular cylindrical tube made of an incompressible magnetoelastic material is subjected to a finite static deformation in the presence of an internal pressure, an axial stretch and an azimuthal or an axial magnetic field. The dependence of the static magnetoelastic deformation on the intensity of the applied magnetic field is analysed for two different magnetoelastic energy density functions. Then, superimposed on this static configuration, incremental axisymmetric motions of the tube and their dependence on the applied magnetic field and deformation parameters are studied. In particular, we show that magnetoelastic coupled waves exist only for particle motions in the azimuthal direction. For particle motion in radial and axial directions, only purely mechanical waves are able to propagate when a magnetic field is absent. The wave speeds as well as the stability of the tube can be controlled by changing the internal pressure, axial stretch and applied magnetic field that demonstrates the applicability of magneto-elastomers as wave guides and vibration absorbers.

Radial Emission Profiles for a Hollow Cathode Glow Discharge in an Axial Magnetic Field

1989 ◽  
Vol 43 (1) ◽  
pp. 141-148 ◽  
Author(s):  
Regis Simonneau ◽  
Richard Sacks
Keyword(s):  
Magnetic Field ◽  
Hollow Cathode ◽  
Neutral Atom ◽  
Permanent Magnets ◽  
Cathode Surface ◽  
Axial Magnetic Field ◽  
Cathode Plasma ◽  
Spatially Resolved ◽  
The Magnetic Field ◽  
The Continuum

Spatially resolved emission measurements are used to characterize the changes in plasma structure resulting from the application of an external magnetic field to an Ar hollow cathode plasma. The field is generated by ring-shaped permanent magnets which are coaxial with the cathode. The magnetic field is normal to the cathode surface and thus forms electron traps which reduce the rate of electron transport normal to the cathode surface. At lower lamp pressure, the magnetic field dramatically changes the spatial distribution of the continuum background and Ar ion radiation. Radiation from neutral-atom cathode material also is affected by the field. The magnetic field has less influence at higher pressure where collisional effects are larger.

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