Hamaguchi Laboratory

Our recent focus in research is on plasma-material interactions in general, including their industrial applications. The aim of research is to understand fundamental mechanics of plasma-material interactions under various conditions. To achieve this, we combine plasma/beam experiments with numerical simulation/modeling. More specifically our current research topics include 1) etching, deposition, and surface modification processes for micro/nano electronics device manufacturing, 2) surface modification and functionalization of biomaterials by plasmas, 3) processing of water and biological systems by atmospheric-pressure plasmas mainly for applications in plasma medicine and plasma agriculture, and 4) dynamics and chemical reactions in plasmas under various conditions, including atmospheric-pressure plasmas.

If you are interested in our research, please feel free to contact me.

Satoshi Hamaguchi
Professor, Division of Materials and Manufacturing Science, Osaka University.

Events & News

Mt. Kongo Hiking
We went hiking at Mt. Kongo, the highest peak of the scenic Kongo-Katsuragi mountain ranges along the Osaka-Nara border.
We held a dinner to say goodbye to Anjar, Jomar, and Nina, and to welcome David, at "Indian Kitchen" in Onohara, Osaka.
The 7th Atomic Layer Process (ALP) Workshop will be held in Tokyo, Japan (on-site only).
All talks will be given in Japanese.
website
We had a lab BBQ party at "FARMER'S BBQ by the Farm UNIVERSAL" near Saito-Nishi Sta., Osaka.
We had Hanami (cherry blossom viewing) at Expo Park.
We held a lab farewell party for Elif-san, Kawabata-kun, and Kotani-kun, at an Indonesian restaurant in Nakatsu, Osaka.
We held a lab Christmas party in the meeting room located in bldg. A12, Osaka University, with lab member's hand-cooked dishes.
Lab Hiking to Mt. Kongo was cancelled because of the weather condition.
We had only dinner which was planned originally to be done after the hiking, at an oriental restaurant near Shinsaibashi, Osaka.
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Mt. Koya Hiking (one night and two days)
We went hiking at Mt. Koya in Wakayama prefecture, aside from our usual lab hikings.
After one-day hike, we stayed at Shukubo (宿坊) which is casual temple lodging, then next day we visited World Heritage temples.
We had a lab BBQ party at Expo Park.
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The following conferences were held jointly in Okinawa, Japan. See their websites for more information.
  • 4th International Conference on Data Driven Plasma Science (ICDDPS-4): website
  • 14th EU-Japan Joint Symposium on Plasma Processing (JSPP-14): website
CAMT (Center for Atomic and Molecular Technologies) has been terminated on the end of March 2023.
From April, our lab belongs to Division of Materials and Manufacturing Science.
Farewell, Welcome, and Graduation Dinner
We held a farewell, welcome, and graduation dinner at an Indonesian restaurant in Nakatsu, Osaka.
The 5th Atomic Layer Process (ALP) Workshop will be held in Osaka, Japan (on-site only).
All talks will be given in Japanese.
website

Plasma Seminars

If you are interested in attending the seminars, please contact us.

"Investigating reaction mechanisms in a hybrid nanocomposite thin film deposition system combining plasma and injection of a colloidal solution"
Dr. Simon Chouteau
Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, Japan
Date: (Wed) 11:00-12:00 (JST)
Location: Main Conference Room (1st floor), Bldg. A12, Suita Campus, Osaka University
Webex Online Conference available

This work focuses on the growth of nanocomposite thin films using aerosol-assisted low-pressure plasma processes. Five studies were carried out with the aim of understanding the fundamental mechanisms involved in this specific category of processes. First, a study of nanocomposite thin film growth using in situ spectroscopic ellipsometry showed that the material input to the sample was alternately matrix- and nanoparticles-predominant. Second, so-called "flash" boiling was identified as the main mechanism for droplet formation in the low-pressure plasma, by confronting an evaporation model to the measured droplet size on the samples' surface. Third, the study of aerosol-surface interaction revealed that hot surfaces lead to "stick-slip" evaporation and Leidenfrost-induced motion on hot surfaces. Then, time-resolved optical emission spectroscopy measurements coupled to a collisional-radiative model were used to look into the aerosol-plasma interaction after the pulsed injection of liquid into a low-pressure argon plasma. The evolution of fundamental plasma properties was determined, bringing to light the variations in electron temperature and electron density caused by aerosol injection. Finally, the insight gained from the previous studies has been applied to grow nanocomposite thin films containing various nanomaterials, namely molecular clusters, spherical nanoparticles, and carbon nanotubes.

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"Secondary electron emission processes in gas discharges"
Dr. Zoltan Donko
Wigner Research Centre for Physics, Hungary
Date: (Tue) 15:30-16:30 (JST)
Location: Main Conference Room (1st floor), Bldg. A12, Suita Campus, Osaka University
Webex Online Conference available

The emission of secondary electrons from the electrodes of gas discharges is indispensable in cold-cathode direct-current (DC) discharges and is often important as well in radiofrequency (RF) plasmas. While in the majority of studies ion-induced electron emission is considered alone, like in the fundamental Paschen theory of gas breakdown, in reality, additional species: metastable atoms, fast ground-state atoms – originating from ion-atom collisions – and ultraviolet photons may lead to the emission of secondary electrons, too. Some while ago, a revision of the classical Townsend theory quantified the contributions of these species in homogeneous-electric-field discharges in argon gas and analyzed the effective secondary electron yield (the ratio of the electron to the ion flux at the electrode) as a function of the reduced electric field, E/N. The results of this extension were subsequently shown not to be directly applicable to DC glow discharges where an inhomogeneous electric field is present in the vicinity of the cathode and the effective electron yield was studied for cathode-fall conditions, too. The effects of secondary electrons in RF capacitively coupled plasmas (CCP) were also addressed in some studies. The most spectacular of these effects is perhaps the “α-γ mode transition”, when the power absorption by the secondary electrons via their acceleration in the sheath electric field becomes dominant over the energy gain of bulk electrons in the ambipolar field near the sheath edge. During the past years, a number of works has targeted the in-situ determination of the effective electron yield. These studies - which will be reviewed in the talk - were all based on combinations of experiments and simulations, comparing, e.g., the spatio-temporal excitation maps for atomic transitions, ion energy distributions at the electrodes, and the DC self-bias voltage formed in CCPs under dual-frequency excitation.

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"AI-driven Reduced Order Modelling for Understanding the Dynamics of Edge Tokamak Plasma Turbulence"
Mr. David Garrido González
Aix Marseille University,CNRS, PIIM UMR 7345, Marseille, France
Date: (Wed) 11:00-12:00 (JST)
Location: Main Conference Room (1st floor), Bldg. A12, Suita Campus, Osaka University
Webex Online Conference available

Abstract
Reduced Order Models (ROMs) have been recently used to understand the complex dynamics of magnetic fusion plasmas [1]. This study introduces a new framework, Artificial Intelligence (AI)-driven Proper Orthogonal Decomposition with Galerkin Projection (AiPoG), which is an AI-driven ROM designed to effectively solve systems of partial differential equations (PDEs) in the context of plasma physics. This framework consists of the combination of three methods: Proper Orthogonal Decomposition (POD), Galerkin Projection, and the Neural Ordinary Differential Equation (NODE) algorithm—a neural network combined with an ODE system solver to learn the system vat·iable dynamics. We present a proof of concept for the AiPoG framework applied to the Hasegawa Wakatani system, a model addressing turbulence in the edge tokamak plasma. The study includes an analysis of initial snapshots, POD reconstructions, and errors, emphasizing the AiPoG's capability to capture the intricate dynamics of edge turbulence. Although recent studies have shown that NODE can be applied to infer dynamical systems driven by PDEs [2], our work marks the first application of NODEs to plasma physics. Leveraging POD, we ascertain that the potential and density fields can be projected into the extracted mode basis for multiple time steps. Subsequently, we employ the NODE to solve the resulting ODE system, combining the predicted amplitudes linearly with the corresponding mode to reconstruct the density and potential fields.

[1] R. Anirudh et al., "2022 Review of Data-Driven Plasma Science," IEEE Transactions on Plasma Science, vol.51, no. 7, pp. 1750-1838, July 2023, doi:10.1109/TPS.2023.3268170.
[2] A. T. Mohan, K. Nagarajan, & D. Livescu, "Learning stable Galerkin models of turbulence with differentiable programing," arXiv preprintarXiv:2107.07559, 2021.

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"Rare Earths Revisited: Dilutely Doped Semiconductors for Microdisplay and Quantum Information Applications"
Prof. Brandon Mitchell
Department of Physics, West Chester University, West Chester, Pennsylvania 19383, USA
Date: (Fri) 10:30-11:00 (JST)
Location: Main Conference Room (1st floor), Bldg. A12, Suita Campus, Osaka University
Webex Online Conference available

Abstract
Developing a "smart society" will require advancements in display and quantum computation technologies. These advancements will come in the form of color-tunable LEDs fabricated on the micrometer scale and the fabrication of systems whose quantum states can be isolated and precisely controlled which can both be addressed by "trapping" rare earth (RE) ions in a semiconducting host. I will discuss the benefits of incorporating RE ions into a semiconductor host, with two anticipated end applications of this work being electrically controlled color-tunable LEDs for micro-display applications and a spectrally-stable electrically-pumped single-photon source operating in the telecom C-band.

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"Theoretical investigation of n-butane isomerization over metal-substituted aluminosilicates"
Dr. Lucas Spiske
Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, Osaka, Japan
Date: (Tue) 15:00-16:00 (JST)
Location: Main Conference Room (1st floor), Bldg. A12, Suita Campus, Osaka University
Webex Online Conference available

Abstract
In today's petrochemical industry, it is paramount to minimize waste products as well as rare and hazardous chemicals used in the processes. In my PhD work, I investigate the catalytic isomerization of n-butane to isobutane using zeolites as catalysts with computational methods. High-level hybrid-functional DFT is used to calculate the energetic barriers of various reaction mechanisms important for the isomerization process. Novel reaction mechanisms aiming to explain conversion between alkanes and olefins during the reaction, as well as the formation of prominent side products, are also presented. The energetic barriers are calculated for a number of zeolite catalysts differing in both acidity and structure, giving insight into their reactivity and confinement effects, respectively. These are then used to draw linear scaling relations, which can ideally be used to predict the reactivity of new zeolite catalyst structures.

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Past Seminars

PiAI Seminars

Seminar Series on "Physics informed Artificial Intelligence in Plasma Science"
For more information, please see here .