Andrew J. Woods

Well Matched Electromagnetic Boundary in FDTD-PIC for Charged Particle Penetration

The authors address the Matched Phase Velocity method for bounding an electromagnetic (EM) domain in the MAGIC finite difference-time domain (FDTD) particle-in-cell (PIC) EM code. Reflected power is shown to be reduced 18 dB compared to the conventional port treatment. Boundary quality is preserved under penetration by charged particles. fields. This approach is versatile and provides self consistent interaction between particles and fields. The MAGIC software includes a broad variety of boundary and material properties as well as particle and field algorithms. We will make use of only a selected subset to illustrate the behavior of the improved CMPV approach. The centered MPV method for bounding an electromagnetic domain will be shown to be effective in reducing unwanted boundary reflections in the MAGIC EM code and has the pleasing symmetry of application that waves may be injected and removed from the simulation via the same numerical methodology, and does not exhibit the unstable behavior of other ABC methods when penetrated by charged particles.

Well Matched Electromagnetic Boundary in FDTD-PIC for Charged Particle Penetration~!2009-08-31~!2009-12-07~!2010-04-13~!

The authors address the Matched Phase Velocity method for bounding an electromagnetic (EM) domain in the MAGIC finite difference-time domain (FDTD) particle-in-cell (PIC) EM code. Reflected power is shown to be reduced 18 dB compared to the conventional port treatment. Boundary quality is preserved under penetration by charged particles.

Robert Barker Memorial Session: Leadership in Plasma Science and Applications

This paper summarizes the Dr. Robert J. Barker memorial session at the IEEE International Conference on Plasma Science 2014. Each section summarizes progress in a plasma research area strongly influenced by Dr. Barkers leadership: 1) plasma medicine; 2) atmospheric-pressure plasmas; 3) high-power microwaves; 4) pulsed power; and 5) numerical simulation of plasmas. He had a profound influence on these and other plasma science applications, as well as on numerous individual researchers. He will be missed greatly.

A short retrospective on the impact of dr Robert Barker on plasma science the magic users group and plasma simulation

Summary form only given. From 1988 through 2010, Dr. Barker, at the Air Force Office of Scientific Research (AFOSR) sponsored a series of research programs. Dr. Barker encouraged the development of a three-way partnership between government, academia and industry. This program provided a number of universities that would have been otherwise unable to afford commercial software with advanced computational physics modeling tools to further their research programs in the areas of plasma science and electro-energetic physics. Mission Research Corporation/ATK was the industry partner in this program, providing the MAGIC software, organizing the user group, customizing MAGIC to better address academic research, and training and supporting fundamental electro-energetic physics research. In this talk I will briefly describe the impact of Dr. Barkers vision of creating this three-way partnership.

A dual phase velocity boundary method for simulation of broadband microwave and millimeter applications

The “Magic Tool Suite” is a Finite-Difference, Time-Domain Particle-in-Cell (FDTD-PIC) software suite employed in the modeling of vacuum electronics devices. The methods of FDTD-PIC are well known and the literature contains the basic equations and descriptions for the solution of Maxwells equations. Because of its computational efficiency and relative ease of implementation this approach is very attractive and widely used. Simulation of broadband response to circuits is challenging. The bandwidths of interest begin relatively close to the cutoff frequency of the output waveguides and span sufficient frequency spectrum that the phase velocity can vary by as much as a factor of 2 or 3. This provides some difficulties in ensuring that the simulation model does not introduce too high a level of spurious reflections far from the band edges to lead to oscillations. The Dual Phase Velocity method (DPV) is an approach that diminishes such effects.

MAGIC3D electromagnetic FDTD-PIC code dense plasma model benchmark

The MAGIC3D EM FDTD PIC plasma code is compared to MAGIC2D and LSP 3D for dense plasma air ionization test problems. Agreement of maximum responses within one percent is demonstrated.

MAGIC3D FDTD EM-PIC code cut cell slow wave serpentine calculation

The MAGIC3D finite difference electromagnetic particle-in-cell (FDTD EM-PIC) code has been upgraded to include non-conformal or “cut” cells. The code solves Maxwells equations in Cartesian coordinates using full and partial cells cut arbitrarily along flat surfaces. The sophisticated cut cell treatment enables cells to be sliced in all directions and fractions. A field remapping algorithm combines small volumes into neighbor cells to prevent undue Courant time step limitations. The code has been applied to reduced generic serpentine slow wave structures with incoming EM and particle beams in order to explore benefits of cut cells in deliberately marginally-zoned treatments. Improved power transmission was seen with cut cells. Reduced unwanted noise occurred in the particle beam case. Benefits were tracked to the smoother geometry of the serpentine sections with cut cells.

Using the higdon operator for the dual phase velocity boundary and the simulation of intermodulation

The “Magic Tool Suite” is a Finite Difference, Time Domain Particle-in-Cell (FDTD-PIC) software suite employed in the modeling of vacuum electronics devices. The methods of FDTD-PIC are well known and the literature contains the basic equations and descriptions for the solution of Maxwells equations. Because of its computational efficiency and relative ease of implementation this approach is very attractive and widely used. Simulation of broadband response to circuits is challenging. The bandwidths of interest begin relatively close to the cutoff frequency of the output waveguides and span sufficient frequency spectrum that the phase velocity can vary by as much as a factor of 2 or 3. This provides some difficulties in ensuring that the simulation model does not introduce too high a level of spurious reflections far from the band edges to lead to oscillations. The Dual Phase Velocity method (DPV) is an approach that diminishes such effects and improves the modeling of intermodulation effects where the input signal has multiple frequency components. An example of intermodulation effects in a multi-stage serpentine waveguide amplifier will be presented.

MAGIC FDTD simulation of complex shapes generated with Sketchup

Summary form only given. The MAGIC Tool Suite [1] is FDTD-PIC software designed for the simulation of plasma wave interactions in complex geometries. Complex geometries often require elaborate command language scripts. Thus prototyping a new device can be cumbersome and time consuming. Recent enhancements to MAGIC allow for more efficient generation of several common complex geometries. In addition, by using Trimble Sketchup we can make the process visual and relatively intuitive. We demonstrate the use of Trimble Sketchup to generate complex three dimensional geometries. Sketchup is attractive as an inexpensive modeling tool which allows for customized scripts (plugins) which can then save the geometry to the command data format used by the MAGIC Tool Suite. Sketchup may be customized with an Application Procedural Interface (API), we provide for easy modeling of complex structure such as waveguide, cavities, helices, and serpentine waveguides. The customization includes: Buttons to select particular shapes, visualization control of the shapes, dialogs to specify material properties, and finally export as MAGIC Tool Suite Script commands. Of particular importance is the automatic generation of the MAGIC command script for the geometry and the specification of coordinate system. In this paper we will illustrate the use of Sketchup to generate the geometry models for the following microwave devices: An helix TWT, a Serpentine traveling wave circuit, and a multi-cavity klystron circuit.

Performance enhancement of MAGIC FDTD-PIC plasma-wave simulations using GPU processing

Present day computers equipped with powerful graphics processing units (GPUs) show considerable promise of increased performance for the electromagnetic (EM) modeler. In order to determine the degree of performance gain achievable for electro-energetic physics computations, the MAGIC EM finite difference-time domain (FDTD) particle-in-cell (PIC) plasma code [1] is undergoing testing for parallel speedup on typical large scale plasma wave EM calculations using GPU processing. The results of the tests are expected to be of great interest to the EM community because MAGIC is widely employed and implements the methods common to many large scale applications. The performance data obtained will quantify the benefits of GPUs, and aid in selecting the proper system including GPUs potentially critical to effectiveness with EM/plasma codes where calculation times often run into days due to small zone and time step requirements. GPUs promise a relatively low cost boost leveraging the vast development driven by the computer game industry.