Research Interests at MCL

Multidisciplinary Studies at MCL can be categorized as follows:

In EM/Plasma aspect: Microwave/Plasma Physics, Photonic Crystals, Compact Millimeter-wave/THz sources, and FEM and FDTD PIC simulations.

In QM aspect: Nano-materials, surface emission physics, quantum transport in low-dimensional systems, and ab initio calculations of material science.

In EM coupled with QM aspect: Nano-optics, surface plasmons, and plasma material surface interaction.

In HPC aspect: Switchless HPC cluster, GPU, Genome SNP Analysis, Artificial Intelligence (AI), and codes for numerical simulations.

Long-term Research Objectives are listed below:

1. Extending Research and Development using high-performance computing including ab initio calculations of materials and EM/Plasmas particle-in-cell simulations.

2. Electrical and optical properties of quantum systems in photonic crystals/Metamaterials.

3. Electron emission mechanisms and surface excitations.

4. Design and development of compact millimeter wave, THz wave, and x-ray sources.

5. Interdisciplinary research on modeling of complex systems such as plasma/surface interactions and physics at edges.

6. New physics and applications that benefit human being, society, and nature such as thermal energy convertors, new energy sources, and high efficiency devices.

Continuing Research Topics in Vacuum Electronic Devices

1. High efficiency field emission based magnetrons for industrial heating and wireless power transmission, injection-locked magnetrons for powering future Linear Accelerators (Linac), and novel High Power Microwave (HPM) sources.

Figure 1. Triode configuration of the A6 relativistic magnetron employing a field emission cathode.

Figure 2. Rising-sun magnetrons employing a field emission cathode designed and developed using accurate and efficient CFDTD PIC modeling exhibit a lot of advantages compared to conventional strapped magnetron employing a thermionic cathode.

2. High power and high efficiency klystrons employing multistage depressed collectors being able to recover waste energy of spent beams for replacing existing Linac klystrons in use.

Figure 3. Electron particle distribution in the five-stage collector of the compact S-band TWT colored with electron kinetic energy from the 3D CFDTD simulations.

3. Novel Traveling Wave Tubes for Space Applications

Figure 4. Electron-beam transmission along the 68-period ladder SWS for an input power of (a) 1, (b) 10, and (c) 100 W, predicted using PIC.

4. Gyrotron simulations---Low frequency oscillations (LFOs), Cavity Interaction (CI), and After Cavity Interaction (ACI).

Figure 5. Phase space of electrons in the Magnetron Injection Gun of the MIT Gyrotron using 3D PIC simulations.

Figure 6. 3-D VSim gyrotron model including a downtaper, an interaction cavity, an uptaper, and an homogeneous waveguide section for accommodating a port boundary condition. 3-D CFDTD PIC simulation results of the MIT gyrotron: (a) output power vs time, (b) FFT of Bx showing a resonant frequency at 110 GHz, and (c) the time-frequency plot showing the time evolution of mode competition.

5. High power and high efficiency MEMS based or 3D Printing based THz devices ---patent in preparation.

Figure 7. Power output of EM sources available showing THz gaps.

6. Some microwave components for industrial applications.

Figure 8. Schematic structure of the MPECVD system and FEM modeling of EM Plasma discharge and interaction

Figure 9. Left: (a) 3-D view of 915 MHz circulator design and (b) The ferrite and metal stage geometry configuration, Middle: Comparison of different ferrite materials’ (a) S11 parameter and (b) S31 parameter. Right: (a) Top view and (b) Side view from port 2 of electric field norm (V/m) for the compact model of the half height circulator.

Energy Related Research---Renewable Energy Sources and Energy Converters or Storages

1. High Efficiency Thermal Energy Converter (HETEC)

Figure 10. Schematic diagrams of a thermionic energy converter with an external load

2. Plasmonic-Based Photovoltaics---High Efficiency Thin Film Solar Cells

Figure 11 (a) Scattering electric field of randomly distributed silver nano-particles and (b) FEM meshes

Computational Material Research---First Principles Calculations

1. Ab initio calculations based on Density Functional Theory.

Figure 12. VASP 3D model of a tungsten substrate (left) with one layer of barium absorbed (right).

Figure 13. Left: (a) Crystal structure of Fe3O4, (b) the black balls denote oxygen atoms and red balls denote A-site (tetrahedral) iron atoms, and (c) the blue balls denote B-site (octahedral) iron atoms. Right: (a) Effective work functions (F) and (b) local work function variation (Δφ) of the magnetite (100) surface A layer under an external electric field from 0.0 (V/Å) to 0.3 (V/Å), (c) charge density and (d) local work function at an electric field of 0.2 (V/Å).

2. Meta-Materials and Photonics Crystals (PCs)---3D Printing

Figure 14. Band Structure of 3D Photonic Crystals using FEM simulations compared with K. Sakoda, Optical Properties of Photonic Crystals, 1st ed. (Springer, 2001)

Figure 15. Left: Schematics of omnidirectional light propagation in 2D PCs for (a) a triangular lattice and (b) a square lattice with kz = k ·sinθ (black solid line) and the in-plane light propagation with kz = 0 (blue dashed line), where θ is the off-plane incident angle. Right: Comparisons of 3D total PDOS calculated by the FEM (black solid line) and the PWEM (green open circles) for a 2D PC with a triangular lattice of air cylinders etched into silicon (εd = 11.90) at a filling ratio of 67%. The total PDOS is contributed from both the radiative (red dotted line) and evanescent (blue dashed line) modes. The PBG calculated by the FEM for the off-plane radiative waves ranges from 0.395(2πc/a) to 0.399(2πc/a) while that for the in-plane case ranges from 0.382(2πc/a) to 0.400(2πc/a).

Artificial Intelligence---Developing Beta Chinese Chess and Smart Image Recognition

1. Beta Chinese Chess

Figure 16. Schematic of Beta Chinese Chess platform based on an open source project developed by Google. Chinese Chess is an ancient game that is deeply embedded in Chinese culture. Millions have played the game across Asia for the past few centuries and spread to the global in recent decades. Improving the AI engine to compete Professional Masters and understanding how human think are the goals. The corresponding algorithms developed might boost AI advancement.

2. Smart Image Recognition

Figure 17. Schematic Face recognition is one of the artificial intelligence (AI) technologies a widely used today or near future in different applications such as advanced human-computer interaction, video surveillance, automatic indexing of images, and video database, etc. We focus on modification and testing of the internal parameters in YOLO V3 to improve the face detection system developed at Hanyang University, Korea for conquering variant environmental challenges, such as a larger database with more than ten thousands of images for different human subjects with different poses and illumination conditions.

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