scholarly journals Different operation regimes of cylindrical triode-type electron accelerator studied by PIC code simulations

2016 ◽  
Vol 35 (1) ◽  
pp. 33-41
Author(s):  
R. Fetzer ◽  
W. An ◽  
A. Weisenburger ◽  
G. Mueller
Keyword(s):  
Laminar Flow ◽  
Virtual Cathode ◽  
Electron Flow ◽  
Target Material ◽  
Grid Voltage ◽  
Particle In Cell ◽  
Beam Energy Density ◽  
Specific Geometry ◽  
Pic Code ◽  
Beam Edge

AbstractThe performance of the converging electron beam generated in cylindrical triodes is systematically studied by particle-in-cell code simulations. Depending on the cathode and grid potentials applied, different operation regimes are identified. For low voltages between cathode and grid, laminar flow and homogeneous beam energy density at the target (anode) is obtained. This applies both to the case of unipolar electron flow and to bipolar flow with counter-streaming ions. Hereby, the electron emission current is enhanced by about 50% for bipolar flow compared with unipolar flow. A further increase by about 20% is obtained when electron backscattering at the target is enhanced due to a change of target material from aluminum to tungsten. For cathode-grid voltages exceeding a critical value, laminar flow is replaced by non-laminar flow regimes. For unipolar electron beams, a virtual cathode forms between grid and target, which leads to an inhomogeneous power density at the target. For the specific geometry investigated and the cathode potential fixed at −120 kV, the cathode-grid voltage threshold for the formation of the virtual cathode is ~32 kV for Al targets and ~28 kV for W targets. For bipolar flow, the laminar flow regime already ends at cathode-grid voltages of ~23 kV (Al target) and ~20 kV (W target), respectively, and is replaced by magnetic insulation at the beam edge. For increasing cathode-grid voltage, the magnetically insulated region extends until beam pinching occurs.

scholarly journals Numerical Aspects of Particle-in-Cell Simulations for Plasma-Motion Modeling of Electric Thrusters

Aerospace ◽  
2021 ◽  
Vol 8 (5) ◽  
pp. 138
Author(s):  
Giuseppe Gallo ◽  
Adriano Isoldi ◽  
Dario Del Gatto ◽  
Raffaele Savino ◽  
Amedeo Capozzoli ◽  
...  
Keyword(s):  
Numerical Model ◽  
Computing Time ◽  
Computational Time ◽  
Electric Motors ◽  
Motion Modeling ◽  
Particle In Cell ◽  
Computing Platform ◽  
Hall Effect Thruster ◽  
Set Up ◽  
Pic Code

The present work is focused on a detailed description of an in-house, particle-in-cell code developed by the authors, whose main aim is to perform highly accurate plasma simulations on an off-the-shelf computing platform in a relatively short computational time, despite the large number of macro-particles employed in the computation. A smart strategy to set up the code is proposed, and in particular, the parallel calculation in GPU is explored as a possible solution for the reduction in computing time. An application on a Hall-effect thruster is shown to validate the PIC numerical model and to highlight the strengths of introducing highly accurate schemes for the electric field interpolation and the macroparticle trajectory integration in the time. A further application on a helicon double-layer thruster is presented, in which the particle-in-cell (PIC) code is used as a fast tool to analyze the performance of these specific electric motors.

Downstream Transport Beam Spill with Particle In Cell (PIC) code Lsp

2021 ◽  
Author(s):  
Derek Neben ◽  
Michael Weller ◽  
Evan Scott
Keyword(s):  
Particle In Cell ◽  
Pic Code

Particle-in-Cell Modeling of Axial and Coaxial Virtual Cathode Oscillators

2016 ◽  
Vol 44 (10) ◽  
pp. 2399-2405 ◽  
Author(s):  
Ayush Saxena ◽  
Amitava Roy ◽  
Krishna V. Kanakgiri ◽  
Sharmila J. Petkar ◽  
Faruk S. Kazi ◽  
...  
Keyword(s):  
Virtual Cathode ◽  
Particle In Cell ◽  
Cell Modeling

Investigating mechanisms of generation in a virtual cathode system using a 3D electron flow model

2014 ◽  
Vol 78 (12) ◽  
pp. 1313-1315 ◽  
Author(s):  
N. S. Frolov ◽  
S. A. Kurkin ◽  
A. A. Koronovskii ◽  
A. E. Hramov ◽  
Yu. A. Kalinin
Keyword(s):  
Flow Model ◽  
Virtual Cathode ◽  
Electron Flow ◽  
3D Electron

scholarly journals Effect of rear surface fields on hot, refluxing and escaping electron populations via numerical simulations

2019 ◽  
Vol 7 ◽  
Author(s):  
D. R. Rusby ◽  
C. D. Armstrong ◽  
G. G. Scott ◽  
M. King ◽  
P. McKenna ◽  
...  
Keyword(s):  
Particle Tracking ◽  
Large Population ◽  
Rear Surface ◽  
Threshold Energy ◽  
Temporal Characteristic ◽  
Hot Electrons ◽  
Hot Electron ◽  
Particle In Cell ◽  
Electron Propagation ◽  
Pic Code

After a population of laser-driven hot electrons traverses a limited thickness solid target, these electrons will encounter the rear surface, creating TV/m fields that heavily influence the subsequent hot-electron propagation. Electrons that fail to overcome the electrostatic potential reflux back into the target. Those electrons that do overcome the field will escape the target. Here, using the particle-in-cell (PIC) code EPOCH and particle tracking of a large population of macro-particles, we investigate the refluxing and escaping electron populations, as well as the magnitude, spatial and temporal evolution of the rear surface electrostatic fields. The temperature of both the escaping and refluxing electrons is reduced by 30%–50% when compared to the initial hot-electron temperature as a function of intensity between $10^{19}$ and $10^{21}~~\text{W}/\text{cm}^{2}$ . Using particle tracking we conclude that the highest energy internal hot electrons are guaranteed to escape up to a threshold energy, below which only a small fraction are able to escape the target. We also examine the temporal characteristic of energy changes of the refluxing and escaping electrons and show that the majority of the energy change is as a result of the temporally evolving electric field that forms on the rear surface.

EARLY OUT-OF-EQUILIBRIUM BEAM-PLASMA EVOLUTION: POSSIBLE FORMATION OF A BEAM RING STRUCTURE

2007 ◽  
Vol 21 (03n04) ◽  
pp. 633-636 ◽  
Author(s):  
M. C. FIRPO ◽  
A. F. LIFSCHITZ
Keyword(s):  
Electron Beam ◽  
Transverse Isotropy ◽  
Ring Structure ◽  
Skin Depth ◽  
Beam Radius ◽  
Particle In Cell ◽  
Beam Plasma ◽  
Initial Stage ◽  
Filamentation Instability ◽  
Beam Edge

We solve analytically the out-of-equilibrium initial stage that follows the injection of a radially finite electron beam into a plasma at rest and test it against particle-in-cell simulations. For initial large beam edge gradients and not too large beam radius, compared to the electron skin depth, the electron beam is shown to evolve into a ring structure. For low enough transverse temperatures, filamentation instability eventually proceeds and saturates when transverse isotropy is reached. The analysis accounts for the variety of very recent experimental beam transverse observations.

scholarly journals Hot electron refluxing in the short intense laser pulse interactions with solid targets and its influence on K-α radiation

Nukleonika ◽  
2015 ◽  
Vol 60 (2) ◽  
pp. 233-237 ◽  
Author(s):  
Vojtěch Horný ◽  
Ondřej Klimo
Keyword(s):  
Strong Electric Field ◽  
Target Material ◽  
Target Thickness ◽  
Intense Laser ◽  
Rear Side ◽  
Hot Electron ◽  
Fast Electrons ◽  
X Ray ◽  
Particle In Cell ◽  
Beam Interaction

Abstract Fast electrons created as a result of the laser beam interaction with a solid target penetrate into the target material and initialize processes leading to the generation of the characteristic X-ray K-α radiation. Due to the strong electric field induced at the rear side of a thin target the transmitted electrons are redirected back into the target. These refluxing electrons increase the K-α radiation yield, as well as the duration of the X-ray pulse and the size of the radiation emitting area. A model describing the electron refluxing was verified via particle-in-cell simulations for non-relativistic electron energies. Using this model it was confirmed that the effect of the electron refluxing on the generated X-ray radiation depends on the target thickness and the target material. A considarable increase of the number of the emitted K-α photons is observed especially for thin targets made of low-Z materials, and for higher hot electron temperatures.

Particle acceleration by lower-hybrid turbulence

2002 ◽  
Vol 68 (3) ◽  
pp. 161-172 ◽  
Author(s):  
R. BINGHAM ◽  
J. M. DAWSON ◽  
V. D. SHAPIRO
Keyword(s):  
Particle Acceleration ◽  
Cyclotron Frequency ◽  
Plasma Frequency ◽  
Energetic Electron ◽  
Wave Turbulence ◽  
Lower Hybrid ◽  
Hybrid Wave ◽  
Lower Hybrid Wave ◽  
Particle In Cell ◽  
Pic Code

We investigate particle acceleration by strong lower-hybrid turbulence produced by the relaxation of an energetic perpendicular ion ring distribution. Ion ring distributions are associated with counterstreaming plasma flows in a magnetic field, and are found at perpendicular shocks as a result of ion reflection from the shock surface. Using a 2½D particle-in-cell (PIC) code that is fully electromagnetic and relativistic, we show that the ion ring is unstable to the generation of strong plasma turbulence at the lower-hybrid resonant frequency. The lower-hybrid wave turbulence collapses in configuration space, producing density cavities. The collapse of the cavities is halted by particle acceleration, producing energetic electron and ion tails. For solar flare plasmas with temperatures of 1 keV and a ratio of the plasma frequency to the electron cyclotron frequency of ½, we demonstrate electron acceleration to energies up to MeV, while the ions are accelerated to energies in the region of several MeV.

scholarly journals EVOLUTION OF THE WAKE WAVE EXCIDED BY THE SEQUENCE OF THE RELATIVISTIC ELECTRON BUNCHES

2019 ◽  
pp. 55-58
Author(s):  
O.K. Vynnyk ◽  
I.O. Anisimov
Keyword(s):  
Collisionless Plasma ◽  
Plasma Waves ◽  
Axially Symmetric ◽  
Particle In Cell ◽  
Wake Field ◽  
Electron Bunches ◽  
Density Maps ◽  
Wake Wave ◽  
Symmetric Geometry ◽  
Pic Code

The amplitude of plasma waves, excited by the resonant sequence of electron bunches, saturates after passage of some number of bunches. This behavior was observed and simulated, using particle-in-cell code, but was not completely explained yet. Our study of this behavior was carried out via computer simulation, using modified PDP3 code − 2D3V PIC code for axially symmetric geometry and relativistic collisionless plasma. Simulation demonstrated that amplitude saturation was caused by the plasma pressing-out from the area of the most intensive wake field. This hypothesis has been verified by the obtained electrical and magnetic field spectra, temperature and density maps and density profile for various simulation times.

Sign in / Sign up

Export Citation Format

Share Document