SIMULATION OF HIGH CURRENT FIELD EMISSION FROM VERTICALLY WELL-ALIGNED METALLIC CARBON NANOTUBES

2004 ◽  
Vol 03 (04n05) ◽  
pp. 677-684 ◽  
Author(s):  
W. S. KOH ◽  
L. K. ANG
Keyword(s):  
Electric Field ◽  
Space Charge ◽  
Field Enhancement ◽  
Smooth Transition ◽  
High Current ◽  
Simulation Code ◽  
Particle In Cell ◽  
Current Regime ◽  
Wide Range ◽  
Cell Simulation

We have studied the intense electron beams emitted from multiple metallic, vertical and well-aligned Carbon Nanotube (CNT) field emitters. A two-dimensional (2D) particle-in-cell simulation code MAGIC2D is used to obtain the I–V characteristics near to the apex of the emitters' surface for a given applied electric field and field enhancement factor over a wide range of parameters. The effects of electron space charge and electric field shielding from neighboring emitters are compared in low current and high current regimes. It is found that the electron space charge is dominant in high current regime, where the Fowler–Nordheim (FN) law becomes the 2D Child–Langmuir (CL) law. The emitter spacing, number of emitters, and emitter's uniformity are also particularly studied, and they are more critical in low current regime. Smooth transition from the FN law to CL law is demonstrated.

scholarly journals Adaptation of the de Hoffmann–Teller frame for quasi-perpendicular collisionless shocks

2015 ◽  
Vol 33 (3) ◽  
pp. 345-350 ◽  
Author(s):  
H. Comişel ◽  
Y. Narita ◽  
U. Motschmann
Keyword(s):  
Shock Wave ◽  
Electric Field ◽  
Shock Layer ◽  
Local Magnetic Field ◽  
Sliding Velocity ◽  
Collisionless Shock ◽  
Collisionless Shocks ◽  
Particle In Cell ◽  
Cell Simulation ◽  
High Mach

Abstract. The concept of the de Hoffmann–Teller frame is revisited for a high Mach-number quasi-perpendicular collisionless shock wave. Particle-in-cell simulation shows that the local magnetic field oscillations in the shock layer introduce a residual motional electric field in the de Hoffmann–Teller frame, which is misleading in that one may interpret that electrons were not accelerated but decelerated in the shock layer. We propose the concept of the adaptive de Hoffmann–Teller (AHT) frame in which the residual convective field is canceled by modulating the sliding velocity of the de Hoffmann–Teller frame. The electrostatic potential evaluated by Liouville mapping supports the potential profile obtained by electric field in this adaptive frame, offering a wide variety of applications in shock wave studies.

Polarized proton beams from a laser-plasma accelerator

2019 ◽  
Vol 34 (36) ◽  
pp. 1942028 ◽  
Author(s):  
Markus Büscher ◽  
Anna Hützen ◽  
Ilhan Engin ◽  
Johannes Thomas ◽  
Alexander Pukhov ◽  
...  
Keyword(s):  
Laser System ◽  
Particle Beam ◽  
Plasma Accelerator ◽  
Simulation Code ◽  
Experimental Realization ◽  
Additional Degree ◽  
Particle In Cell ◽  
Polarized Proton ◽  
Cell Simulation ◽  
Under Construction

We report on the concept of an innovative laser-driven plasma accelerator for polarized proton (or deuteron) beams with a kinetic energy up to several GeV. In order to model the motion of the particle spins in the plasmas, these have been implemented as an additional degree of freedom into the Particle-in-Cell simulation code VLPL. For the experimental realization, a polarized HCl gas-jet target is under construction, where the degree of proton polarization is determined with a Lamb-shift polarimeter. The final experiments, aiming at the first observation of a polarized particle beam from laser-generated plasmas, will be carried out at the 10 PW laser system SULF at SIOM/Shanghai.

scholarly journals Analysis and simulation of BGK electron holes

1999 ◽  
Vol 6 (3/4) ◽  
pp. 211-219 ◽  
Author(s):  
L. Muschietti ◽  
I. Roth ◽  
R. E. Ergun ◽  
C. W. Carlson
Keyword(s):  
Magnetic Field ◽  
Incident Beam ◽  
Distribution Functions ◽  
Simulation Code ◽  
Nonlinear Structure ◽  
Trapped Electrons ◽  
Particle In Cell ◽  
Cell Simulation ◽  
Electron Holes ◽  
The Stability

Abstract. Recent observations from satellites crossing regions of magnetic-field-aligned electron streams reveal solitary potential structures that move at speeds much greater than the ion acoustic/thermal velocity. The structures appear as positive potential pulses rapidly drifting along the magnetic field, and are electrostatic in their rest frame. We interpret them as BGK electron holes supported by a drifting population of trapped electrons. Using Laplace transforms, we analyse the behavior of one phase-space electron hole. The resulting potential shapes and electron distribution functions are self-consistent and compatible with the field and particle data associated with the observed pulses. In particular, the spatial width increases with increasing amplitude. The stability of the analytic solution is tested by means of a two-dimensional particle-in-cell simulation code with open boundaries. We consider a strongly magnetized parameter regime in which the bounce frequency of the trapped electrons is much less than their gyrofrequency. Our investigation includes the influence of the ions, which in the frame of the hole appear as an incident beam, and impinge on the BGK potential with considerable energy. The nonlinear structure is remarkably resilient

scholarly journals ELBA (electron beams in accelerators) particle simulation code

1994 ◽  
Vol 12 (2) ◽  
pp. 273-282 ◽  
Author(s):  
Glenn Joyce ◽  
Jonathan Krall ◽  
Steven Slinker
Keyword(s):  
Large Scale ◽  
Electron Beams ◽  
Three Dimensional ◽  
Forward Direction ◽  
Laboratory Frame ◽  
Particle Simulation ◽  
Simulation Code ◽  
Particle In Cell ◽  
Charged Particle Beams ◽  
Cell Simulation

ELBA is a three-dimensional, particle-in-cell, simulation code that has been developed to study the propagation and transport of relativistic charged particle beams. The code is particularly suited to the simulation of relativistic electron beams propagating through collisionless or slightly collisional plasmas or through external electric or magnetic fields. Particle motion is followed via a coordinate “window” in the laboratory frame that moves at the speed of light. This scheme allows us to model only the immediate vicinity of the beam. Because no information can move in the forward direction in these coordinates, particle and field data can be handled in a simple way that allows for very large scale simulations. A mapping scheme has been implemented that, with corrections to Maxwell's equations, allows the inclusion of bends in the simulation system.

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