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, R3 Institute of Newly-Emerging Science Design (INSD), the University of Osaka.

Events & News

Farewell Dinner
We held a farewell party for Kang-kun and Prof. Karahashi.
Our lab has moved to the new address: Co-Creation Building B in Toyonaka campus.
For more details, please see the "Contact" page.
Dinner
We had a dinner with CAMT members.
CAMT (Center for Atomic and Molecular Technologies) was a part of the Graduate School of Engineering, and it has been terminated on the end of March 2023.
Lab Hiking
We went hiking at Suma trail (Uma-No-Se).
Hanami
We had Hanami (cherry blossom viewing) at Expo Park.
Our lab's affiliation has changed from the Graduate School of Engineering to the R3 Institute of Newly-Emerging Science Design (INSD), the University of Osaka.
However, the lab is still located in Building A12 in Suita campus until a new building construction is completed.
Farewell/Welcome Party
We held a farewell party for Fujita-kun, Tanaka-kun, Kometani-kun, and Nakano-kun and a welcome party for Matteo from Milan University.
We held an end-of-the-year party in our lab with pizza and games.
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.

Plasma Seminars

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

"Load Control Battery Strategy based on Backpropagation and Simulated Annealing Training Performance"
Dr. Enggar Alfianto
Department of Electrical Engineering, Institut Teknologi Adhi Tama, Surabaya, Indonesia
Date: (Fri) 14:00-15:00 (JST)
Location: Rm. 607, Toyonaka Co-Creation Building B, the University of Osaka
Webex Online Conference available

Nowadays, the light control system only uses scheduling, so if the season changes, the system becomes less effective. This study aims to compare the backpropagation (BP) and simulated annealing (SA) algorithm training performances for the ANN system. The selection of the ANN method for estimating the intensity of solar radiation is because it can estimate the daily or hourly average solar radiation with high accuracy. In order to find out the best performance, this research compares BP and SA algorithms based on their Mean Square Error (MSE) and Absolute Error (AE) values. Based on the results, this study shows that MSE and AE values for SA are better than BP. The MSE value of SA is 0.047338156 lower than BP, while the AE value of SA is 19.26% lower than BP. The results of this study prove that for training on a supervised control system using ANN, simulated annealing could be prioritized in the active power load control strategy.

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"Towards More Precise Species Number Density Determination via Iterative Actinometry"
Ms. Mariana Ribeiro
in collaboration with Tiago Silva, Vasco Guerra, and Nikolay Britun
Instituto de Plasmas e Fusão Nuclear (IPFN), Instituto Superior Técnico - Universidade de Lisboa (IST-UL), Lisbon
Date: (Tue) 14:00-15:00 (JST)
Location: Rm. 607, Toyonaka Co-Creation Building B, the University of Osaka
Webex Online Conference available

The accurate determination of reactive species number densities is essential for understanding and optimizing plasma processes, particularly in applications such as plasma etching, where atomic fluorine plays a key role. Optical Emission Spectroscopy (OES), and especially actinometry, is widely used for this purpose due to its non-intrusive nature, simplicity, and low cost. In actinometry, the ground-state density of a target species is inferred from the emission intensity ratio between that species and a reference actinometer gas, typically a noble gas of known concentration [1]. However, the accuracy of this technique is often compromised by the assumption of a Maxwellian Electron Energy Distribution Function (EEDF), which may not be valid in low-temperature, chemically reactive, and non-equilibrium plasmas [2,3].
To address this limitation, this work combines actinometric measurements with advanced numerical modeling of the EEDF. This is achieved using the LoKI (Low-temperature Kinetics) [4,5] framework developed at IPFN, which includes a Boltzmann solver (LoKI-B) and a Monte Carlo simulation tool (LoKI-MC) for computing the EEDF. These solvers allow us to move beyond the Maxwellian approximation, enabling a more physically consistent description of electron kinetics. This, in turn, allows for the calculation of realistic electron-impact excitation rate coefficients and the direct estimation of the reduced electric field (E/N) from spectroscopic data, facilitating potential validation against independent diagnostics. The proposed iterative actinometry scheme begins with an initial density estimate based on a Maxwellian EEDF. This is refined through numerical EEDF modeling, leading to updated rate coefficients and recalculated species densities. The process is repeated until convergence to a self-consistent solution is reached.
By integrating kinetic modeling with experimental diagnostics, this approach significantly improves the accuracy and reliability of species density determinations in CF4-based plasmas and supports the development of more robust plasma monitoring strategies for processing applications.

    References
  1. J. W. Coburn and M. Chen, J. Appl. Phys. 51, 3134 (1980).
  2. Phys. Plasmas 31, 103510 (2024).
  3. Britun et al., J. Appl. Phys. 136, 111101 (2024).
  4. A. Tejero-del-Caz et al., Plasma Sources Sci. Technol. 28, 043001 (2019).
  5. Dias T.C., Tejero-del-Caz A., Alves L.L., and Guerra V., Comput. Phys. Commun. 282, 108554 (2023).

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"Surface recombination in Pyrex in oxygen-containing plasmas: mesoscopic modelling and comparisons with experiments"
Dr. Pedro Viegas
Instituto de Plasmas e Fusão Nuclear (IPFN), Instituto Superior Técnico - Universidade de Lisboa (IST-UL), Lisbon
Date: (Mon) 14:00-15:00 (JST)
Location: Rm. 607, Toyonaka Co-Creation Building B, the University of Osaka
Webex Online Conference available

Surfaces interact with either active discharges or their afterglow in most plasma processes, via heterogeneous surface kinetics. These processes can affect both plasma and surface properties. In particular, in oxygen-containing discharges, the adsorption and recombination of atomic oxygen on reactor surfaces determine the gas composition, the availability of O for important volume reactions (e.g.: CO2 + O → CO + O2; CO + O + M → CO2 + M) and eventually the flux of reactive oxygen species (ROS) towards target surfaces. The loss frequencies of O atoms have been measured in the positive column of O2 and CO2 glow discharges in a Pyrex tube (borosilicate glass), for several pressures, currents and wall temperatures. However, the surface mechanisms determining the recombination of O are not fully known yet. In particular, the increasing atomic oxygen recombination frequency and probability with decreasing pressure for a plasma operating in the pressure range between 0.27 mbar (0.2 Torr) and 1 mbar (0.75 Torr) is not fully understood. It is complemented by an increase of the recombination probability with current observed in the same pressure range, which is not the case at higher pressures. In this work the kinetics of plasma species interacting with the surface is simulated. The description of surface kinetics proceeds via mesoscopic modelling with a new reaction scheme including O+O and O+O2 surface recombination reactions. The conditions of the experiments are addressed in the simulations, whose results are directly compared with experimental measurements, describing the experimental dependence of the atomic oxygen recombination probability on pressure, current and wall temperature. Moreover, the newly developed model demonstrates that the plasma has important effects on the surface at low pressures and allows to identify and understand the most important O recombination mechanisms for each condition.

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"Scientific Workflows for Advanced Material Simulations with SimStack in the Context of European Digitization Initiatives” Probes"
Dr. Jörg Schaarschmidt
in collaboration with Buldin, A.1; Hickel, T.2; Wenzel, W.1
1Karlsruher Institut für Technologie (KIT), Karlsruhe; Germany
2Bundesanstalt für Materialforschung und -prüfung (BAM), Berlin, Germany
Date: (Tue) 11:00-12:00 (JST)
Location: Rm. 607, Toyonaka Co-Creation Building B, the University of Osaka
Webex Online Conference available

Modern materials research often relies on combining multiple specialized simulation tools to model material behavior across different length and time scales. However, chaining these complex scientific software packages into coherent workflows, while adhering to FAIR principles, poses significant technical challenges—especially when high-performance computing (HPC) resources are involved. This talk will introduce the German digitalization initiative in material science: MaterialDigital (https://material-digital.de), including the major concepts of the initiative such as semantic interoperability and scientific workflow technology. It will furthermore introduce SimStack, one of the tow supported Workflow frameworks, its design concepts and technical features. We will demonstrate its real-world applicability through two examples: a multi-scale simulation of charge transport in OLEDs, and a general EV curve calculation used to highlight transferability of these concepts between different Workflow frameworks (https://github.com/materialdigital/ADIS2023/).

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"On the Determination of Energy and Particle Fluxes towards Surfaces in Plasma Processing by “Non-Conventional” Probes"
Prof. Dr. Holger Kersten
in collaboration with D. Zuhayra, C. Adam, T. Trottenberg and V. Schneider
Institut für Experimentelle und Angewandte Physik
AG PlasmaPhysik / PlasmaTechnologie
Christian-Albrechts-Universität zu Kiel
Leibnizstr.19, D-24098 Kiel, Germany
Date: (Fri) 14:00-15:00 (JST)
Location: Main Conference Room (1st floor), Bldg. A12, Suita Campus, the University of Osaka
Webex Online Conference available

The diagnostics of electrons and ions in plasmas and the fluxes of charged and neutral species toward plasma-facing surfaces along with their energy and momentum transfer will be discussed. The focus is laid on the fundamentals of “non-conventional” calorimetric (CP) and force probes (FP) [1,2] as well as their combination with common Langmuir probes (LP) and retarding potential analyzers (RPA) for application to non-equilibrium plasmas and ion beams. These rather simple methods are useful tools for the measurement of overall, not species-resolved, ions and neutral species and energy fluxes toward surfaces. Although the diagnostics have their roots in the beginnings of plasma research, they were gradually refined to match the requirements of plasma environments in industry, such as rf-discharges, reactive plasmas, dusty plasmas, and atmospheric pressure plasmas. Of particular interest is the combination of different types of probes, e.g. retarding potential analyzer (RPA) and passive thermal probe (PTP) [3]. The PTP serves as collector, in front of which three centrally aligned grids are operated as the retarding field system. In this setup the collector does not only measure the incoming ion current depending on the voltage applied to the grids of the RPA, but also the incoming energy flux density of the impinging ions or neutrals, respectively. The ion energy distribution (IED) is determined regarding the energy exchange of the neutral background gas with the ions extracted from the plasma source (charge exchange collisions) and the measured energy influx can even deliver information about fast neutrals and chemical reactions, recombination and secondary electrons. Furthermore, for thin film deposition by sputtering it is essential to determine the sputtering yield as well as the angular distribution of sputtered atoms. In addition to simulations (TRIM,TRIDYN etc. [4]) an experimental determination of the related quantities is highly demanded. For this purpose, we developed a suitable interferometric force probe [5,6]. The sensitive FP bends a few μm due to momentum transfer by the bombarding and released particles, i.e. sputtered target atoms and recoiled ions. By knowing the material properties of the cantilever and by measuring its deflection, the transferred momentum, e.g. the force in μN range, can be determined experimentally.

  1. Benedikt, J., Kersten, H., Piel, A., Plasma Sources Sci. Technol., 30(2021), 033001.
  2. Rosenfeldt, L., Hansen, L., Kersten, H., IEEE Trans. Plasma Sci. 49(2021), 3325.
  3. Schlichting, F., Kersten, H., Eur. Phys. J. Techniques Instrument. 10(2023), 19.
  4. Biersack, J.P., Eckstein, W., Appl. Phys. A 34(1984), 73.
  5. Trottenberg, T., Spethmann, A., Kersten, H., Eur. Phys. J. Tech. Instrum. 5(2018), 3.
  6. Klette, M., Maas, M., Trottenberg, T., Kersten, H., J. Vac. Sci. Technol. A 38(2020), 033013

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Past Seminars

PiAI Seminars

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