Magnetic modeling and characterization
Stoner-Wohlfarth model, Preisach model, vibrating sample magnetometer (VSM), magneto-optic Kerr effect (MOKE)
Modeling and characterizing magnetic materials for various applications using a Quantum Design VersaLab, a custom MOKE, a GMW + MMR Technologies Hall-effect setup. Current efforts include the following:
- Inductive coil magnetic resonance detection
- Magneto-optic switches
- Microstrip transmission lines
High-temperature superconductors, HTS degaussing, HTS cables
Type-II superconductors, including high-temperature superconductors, are characterized by the coexistence of a normal-conducting and a superconducting behavior in a mixed-state region. In this state, the superconductor is partially penetrated by quantized magnetic flux tubes or fluxoids, a phenomenon called flux pinning. Flux pinning is known to be the intrinsic reason for hysteresis.
The continuous advancement of high-temperature superconductors (HTS) technology has empowered numerous military applications. Copper coils have been traditionally used to actively reduce the magnetic signature of a naval vessel, a process called degaussing. The U.S. Navy has recently started using HTS degaussing systems, reducing the size and weight requirements by a significant margin. Press releases in the last couple of years reveal the U.S. Navy’s plan to expand the use of HTS in the fleet through power transmission, power generation, and several other applications. The proposed higher-level model provides a computationally-efficient tool capable of predicting the hysteretic magnetization of HTS, an increasingly-used technology on naval vessels.
US Navy to order high temperature superconductor equipment
Magnetization, magnetostriction, and stress effects
Collaborators: Professor Della Torre (GWU) and Institute for Magnetics Research
Keywords: deperming, degaussing, Preisach, magnetic hysteresis
The interplay between the earth’s magnetic field, the navigation stresses, and the magnetism of a naval vessel continuously alter its magnetic signature, making it prone to detection by undersea mines. Our Preisach-type magnetic models, when coupled with FEM solvers, can predict the magnetic signature of non-trivial ferromagnetic geometries.
Magnetocaloric effect and magnetic refrigeration
Collaborators: Professor Bennett (GWU) and Institute for Magnetics Research
Keywords: gadolinium, Heusler alloys, magnetic transitions
Magnetic materials change their thermodynamic properties when subjected to a changing magnetic field. In particular, if the change happens under adiabatic conditions, the temperature of the material changes. The magnetocaloric effect (MCE) has a growing potential for efficient magnetic refrigeration near room temperature.
Actuation of ferromagnetic microrobots
Collaborators: Professors Firebaugh (USNA), Professor Piepmeier (USNA), and Professor Khalil (GUC)
Keywords: microrobot, magnetic actuation
Wireless microrobot control has a wide range of useful medical, biological, and industrial applications. We are developing a magnetic actuation and visual sensor system capable of controlling a microrobot in a three-dimensional fluidic environment.
NIST microbotics challenge