Research

 

Plasma Surface Interaction

Arcarc2

Thermal Plasma & Multiphysics Modelling

Thermal plasmas are widely used in a lot of applications and the understanding or some improvement of the corresponding processes, and the modelling of the plasma is becoming a hotspot in recent years. Here a secondary development is applied to reinforce ANSYS Fluent to have the capability of multiphysics coupling to analyze the complicated multiphysics system such as thermal plasmas. In this application, flow dynamics, heat transfer, species transport and EM field are coupled together, and subroutines are under development to predict the behavior of the thermal plasmas and the effect of external factors. The modeling work will be supplemented with experimentally determined data on gas temperature and breakdown strength for gas outflow control and optimization.

Arc Roots Instability and Pattern Formation

 

  • The arc hopping dynamics

 

The phenomena of an arc hopping along the electrodes have been invariably observed in the Jacob’s Ladder. The major reason lies in the nonlinear plasma sheath. Due to Debye shielding, the space charge in plasma will assembly on the boundary wall/electrode which forms a charge layer, namely the sheath. Due to this charge layer, there will be a potential drop across the plasma-solid interface. The magnitude of this potential drop is susceptible to the charge flux which gives rise to the negative differential resistance (NDR). The NDR is responsible for the observed hopping dynamics, as well as the surface pattern formation on the electrodes. This idea have been numerically demonstrated that the MHD based simulation model,  incorporating the NDR featured sheath layer,  does capture the hopping pattern of a travelling arc along the Jacob’s Ladder as shown in the video.

Rational Design of Advanced Polymeric Capacitor Films

Muri

Multidisciplinary University Research Initiative (MURI)

Rational design of new polymeric materials with attractive properties (high dielectric constant, high breakdown strength, low loss, appropriate glass transition temperature, etc.) is needed to surpass the properties of BOPP in the application of high energy density capacitors.

This Multidisciplinary University Research Initiative (MURI) is sponsored by the Office of Naval Research. The primary objective of this integrated research program is to design new classes of polymeric materials with high dielectric constant and high breakdown strength, suitable for application in high voltage, high energy density capacitor technologies. We seek to achieve this objective through state-of-the-art “scale-bridging” computations, synthesis, processing, and electrical characterization, and through the creation of a relational database. Participants include University of Connecticut, The University of Akron, Columbia University, The Pennsylvania State University, and  Rensselaer Polytechnic Institute (RPI). Link to MURI website

Space Charge & HVDC

wikipedia list of HVDC projects modified PEA system with electric heaters for thermal gradient

  • Background of HVDC

High-voltage direct current (HVDC) offers efficient non-synchronized bulk electric power transmissions with economic benefits of reduced power loss and enhanced stability, and has been used widely for grid interconnection, renewable integrations and grid decongestions.  Free from reactive power loss, HVDC cables become viable solutions for submarine power transmission, off-shore wind power integration, harsh environment electrification and city in-feeds.

  • Space Charge Patterns under Thermal Gradient

Direct observation of space charge injection and transport in solid dielectrics, as well as their spatial evolution over time, is of great importance in the investigation of design stress and the aging mechanism of engineering dielectrics under high electrical DC field. Through model-aided design, the parallel plate, pulsed-electroacoustic space charge profiling technique is extended to include thermal gradient in thin films. The space charge behavior and dynamics within flat dielectric specimens in the presence of thermal gradient have been studied extensively through the modified pulsed-electroacoustic system as shown in Fig. 1, to provide insights into the high-field aging mechanisms of new materials developed for energy efficient power devices and renewable integration.

Frequency Accelerated Aging for EPR

accelated aing of EPR

  • EPR Cables

Shielded distribution cable is employed over the range from a few thousand volts (kV) to about 69 kV to distribute electric power on a local basis in urban and suburban areas without the use of overhead wires. The key element of such cable is the electrical insulation which supports the very high voltage between the conductor and the grounded shield which assures that the electric field remains within the cable. Two insulation technologies compete in the market; insulation based on mineral filled ethylene propylene rubber (EPR) and insulation based on relatively pure cross linked polyethylene (XLPE or TR-XLPE).

  •  Frequency Accelerated Aging

 

High Field Study
  • Needle Experiment
  • Pre-breakdown Condition Measurement