Title
Axisymmetric charge-conservative electromagnetic particle simulation algorithm on unstructured grids: Application to microwave vacuum electronic devices.
Abstract
We present a charge-conservative electromagnetic particle-in-cell (EM-PIC) algorithm optimized for the analysis of vacuum electronic devices (VEDs) with cylindrical symmetry (axisymmetry). We exploit the axisymmetry present in the device geometry, fields, and sources to reduce the dimensionality of the problem from 3D to 2D. Further, we employ ‘transformation optics’ principles to map the original problem in polar coordinates with metric tensor diag(1,ρ2,1) to an equivalent problem on a Cartesian metric tensor diag(1,1,1) with an effective (artificial) inhomogeneous medium introduced. The resulting problem in the meridian (ρz) plane is discretized using an unstructured 2D mesh considering TEϕ-polarized fields. Electromagnetic field and source (node-based charges and edge-based currents) variables are expressed as differential forms of various degrees, and discretized using Whitney forms. Using leapfrog time integration, we obtain a mixed E−B finite-element time-domain scheme for the full-discrete Maxwell's equations. We achieve a local and explicit time update for the field equations by employing the sparse approximate inverse (SPAI) algorithm. Interpolating field values to particles' positions for solving Newton–Lorentz equations of motion is also done via Whitney forms. Particles are advanced using the Boris algorithm with relativistic correction. A recently introduced charge-conserving scatter scheme tailored for 2D unstructured grids is used in the scatter step. The algorithm is validated considering cylindrical cavity and space-charge-limited cylindrical diode problems. We use the algorithm to investigate the physical performance of VEDs designed to harness particle bunching effects arising from the coherent (resonance) Cerenkov electron beam interactions within micro-machined slow wave structures.
Year
DOI
Venue
2017
10.1016/j.jcp.2017.06.016
Journal of Computational Physics
Keywords
Field
DocType
Electromagnetic simulation,Particle-in-cell,Unstructured meshes,Vacuum electronic devices,Backward-wave oscillator,Cerenkov radiation
Rotational symmetry,Mathematical optimization,Particle-in-cell,Mathematical analysis,Transformation optics,Algorithm,Polar coordinate system,Metric tensor,Equations of motion,Electromagnetic field,Cartesian coordinate system,Physics
Journal
Volume
ISSN
Citations 
346
0021-9991
4
PageRank 
References 
Authors
0.47
4
5
Name
Order
Citations
PageRank
Dong-Yeop Na141.14
Yuri A. Omelchenko2111.22
Haksu Moon3152.46
Ben-Hur V. Borges4124.01
Fernando L. Teixeira59716.97