Quantemol’s QDB plasma chemistry library now supports the OverViz chemistry format. Simply export a chemistry from QDB in the OverViz format (includes both gas and surface chemistries), then load them directly into any of the OverViz modules for plasma simulation.
OverViz users now have even more flexibility in defining complex chemistries for simulation, whether loading from VizData, importing from QDB, or creating their own. QDB membership required for QDB chemistry access. Contact us at firstname.lastname@example.org to learn more.
Esgee will present “High-fidelity Multi-Length Scale Modeling of Spacecraft Charging in GEO orbit” at the 15th Spacecraft Charging Technology Symposium 25-29 June, 2018 at the Integrated Research Center of Kobe University in Japan.
This study describes high-fidelity modeling of spacecraft charging in GEO orbit environment and the resulting incipient vacuum arcing on the spacecraft’s surface. A satellite in GEO environment is subject to continuous bombardment by highly energetic charged particles that accumulate over time on dielectric surfaces resulting in differential voltages between surfaces. For sufficiently large differential voltages, the electric field at sharp corners or protrusions may exceed the threshold for field electron emission that is accompanied by explosive emission of material from the feature. This event constitutes the start of a vacuum arcing event with resulting damage to the spacecraft structure. In this work, a high-fidelity computational model with unstructured meshing framework is used. This framework allows of a multi-length scale resolution of small spacecraft features while fully representing the entire spacecraft geometry. The self-consistent electrostatic potential equation is solved in conjunction with particle tracking to resolve electric-field profiles on the spacecraft surface. Further, the effects of a variety of surface electron emission processes (including secondary electron and photoelectron emission) is represented.
We present a hybrid, fluid-particle plasma model that is used to investigate the plasma discharge and ion extraction behaviors of a radio-frequency gridded ion thruster (RIT). The hybrid approach combines a fluid formulation for plasma governing equations with a kinetic particle formulation for ion behaviors. The self-consistent plasma model includes fully coupled electromagnetics and RF circuit models. Ion particles are dynamically generated from ionization rates in the discharge and tracked as they are extracted from the chamber by a series of electrostatically biased grids. This hybrid approach offers an accurate representation of ion optics coupled with an efficient representation of bulk plasma discharge and chamber operating conditions within a single coupled simulation.
Results are presented for an axisymmetric model of an RIT-3.5. Predicted ion density distributions and ion optics are compared to literature with reasonable agreement. Performance sensitivity to grid potentials are studied to demonstrate model application to thruster performance optimization. The OverViz Simulation Suite, with coupled non-equilibrium plasma and kinetic particle modules, is used to perform the simulations.
The maximum lifetime of a spark plug is limited by electrode erosion. Over the course of millions of repeated sparking events, the electrode material ablates and the electrode gap increases which degrades performance. Once a critical gap is reached, the spark plug is no longer operational and must be replaced. Due to the long relevant time scales over which erosion occurs, and the difficulty of analyzing the spark plug environment during operation, determining spark plug lifetime typically requires extensive field testing.
The objective of this work is use a computational model that can accurately simulate the electrode erosion process and make predictions on the effective lifetime. The problem is challenging in that there are a vast range of time scales, all of which must be resolved to model the erosion. Time scales range from milliseconds needed to resolve arc physics up to days and weeks for time timescales of electrode deformation due to ablation.
As a first step, dynamic coupling between arc physics and an ablating, eroding electrode is developed. An existing commercial arc solver code-VizSpark, capable of modelling the spark event with high fidelity, is used to model the arc physics which determine the net heat fluxes to the electrodes. The electrodes are modelled using an immersed object method, which allows them to dynamically change in shape as the simulation progresses. Mass flux from the electrodes due to ablation is modelled using temperature dependent metal vapor pressure curves. As mass is removed from the electrode-gas interface, the immersed object dynamically deforms, which in turn modifies the gap voltage and the arc physics. Overall, this approach provides predictive capability for the arc-induced erosion over the entire life-time of the spark-plug.
High-voltage relays perform a key role in determining safety and protections of Electric Vehicles(EV)/ hybrid automotive systems. The primary function of a high voltage relay is to mechanically separate electrodes under a short circuit situation, and isolate the motor drive electronics from impending damage due to high currents (~1000 A). As the relay breaks contact, significant arcing can occur due to high currents. Several methods can be applied to ensure immediate mitigation of arc within the relay, thereby reducing the electrical cutoff time. One such technique is to draw the arc towards the walls of a hermetically sealed chamber (using external magnets), and quenching it as it makes contact with the wall. Other techniques involve using an inert gas within the chamber to prevent arcing to occur in the first place.
This paper discusses the numerical modeling of arc formation and mitigation inside sealed electric vehicle relay. A high-fidelity, multi-dimensional, equilibrium arc solver-VizSpark is used to model the dynamics of arc formation and mitigation. Electrode motion is modeled using an immersed object method. The effect of several parameters such as pressure, gas composition and magnetic field strength on arc propagation speeds and cut-off time are studied.
We are pleased to announce the release of OverViz Simulation Suite version 2.2. This includes the first release of VizGrain with full integration into the OverViz simulation framework, enabling macro-particle dynamics for hybrid plasma-fluid-electromagnetics simulations. Key new features include: Direct Simulation Monte Carlo (DSMC) particle modeling in VizGrain; dust particle and boundary surface changing; enhanced particle collision modeling; new robust, compressible flow solver in VizFlow applicable across wide range of Mach numbers; now support multiple background species in VizGlow; improved speed and accuracy of time domain electromagnetic simulations in VizEM; new nonlinear solver to improve accuracy and robustness of convergence on complex meshes; user interface enhancements; and much more.