Characterization of Argon/Hydrogen Inductively Coupled Plasma for Carbon Removal over Multilayer Thin Films

Inductively coupled plasma with an argon/hydrogen (Ar/H2) mixture is a potential solution to many surface treatment problems, especially when encountering carbon contamination in optical X-ray and extreme ultraviolet instruments. Removing carbon contamination on multilayer thin films with Ar/H2 plasma extends the lifetime of the above devices. To further investigate the reaction between plasma and carbon, both optical emission spectroscopy and finite element method with multiphysics fields were employed. The results demonstrated that the intensities of the Balmer lines were in good agreement with the densities of the radical hydrogen atoms from the simulation model, showing a dependence on the mixing ratio. At an electrical input power of 165 W and a total pressure of 5 Pa, an optimum mixing ratio of about 35 ± 5 % hydrogen produced the highest density of hydrogen radicals, coinciding with the highest carbon removal rate. This shows that the carbon removal with Ar/H2 plasma was mainly controlled by the density of hydrogen radicals, and the mixing ratio showed a significant impact on the removal rates

Inductive Medium Pressure UV-Source

Abstract: In this paper, an efficient inductively coupled medium pressure source for ultraviolet radiation (UV-source) is demonstrated. The lamp was operated with powers up to 3kW while the radiation and the coldest point temperature were measured. In addition, different coil geometries were investigated. Here a symmetrical and asymmetrical winding density were compared. Also the operation pressures and DC to radiation efficiencies are presented. In this work, an operation pressure of one atmosphere and an UV-efficiency (200–380 nm) of 15.5% was achieved. This is comparable to conventional medium pressure Hg-lamp technology. The main advantage of the presented inductive lamp is the electrodeless operation and therefore the longer service life, since an electrode failure is eliminated

Plasma Water Activation with an Inductive Plasma Torch at Atmospheric Pressure

The production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), collectively referred to as RONS, has been of increasing interest in recent years. This is based on the wide range of applications for the components mentioned. Examples include the food industry and agriculture or biological applications [1 – 3]. The generation of RONS by plasma-liquid interaction in plasma-activated water is a widely used method. Due to the plasma properties, such as high electron temperatures at low gas temperatures, mainly cold or non-equilibrium plasmas are used [4 – 5]. Plasmas in thermal equilibrium at atmospheric pressure have so far played a subordinate role in PAW generation due to their moderate electron temperatures and high thermal losses. This leads to a lack of publications in this field. In our work, we have developed an inductively driven plasma (ICP) torch, which was used for plasma water activation. An atmospheric pressure inductive Argon plasma was generated with a power of 1.2 kW at a frequency of 3 MHz. The used setup is shown in Figure 1. The plasma was pointed to distilled water in a distance of 1 cm. During a one-hour treatment, the concentration of hydrogen peroxide (H2 O2), nitrite (NO2 −), nitrate (NO−3) and the pH value was measured every 10 minutes by using Quantofix test strips (Peroxide 100, Nitrite, Nitrate 100, pH-Fix 0-14, Machery-Nagel, Düren, Germany). Furthermore, a simulation model of the lab setup used was created. The FEM software COMSOL multiphysics was used to simulate the plasma behaviour and to determine the electron temperature at the atmosphere and the water impact region [6]. With the results, the formation rate of the components mentioned were approximated and compared with other methods for PAW generation. 1. Bradu, C.; Kutasi, K.; Magureanu, M.; Puaˇ c, N.; Živkovi´ c, S. Reactive nitrogen species in plasma-activated water: generation chemistry and application in agriculture. Journal of Physics D: Applied Physics 2020 , 53, 223001. https://doi.org/10.1088/1361-6463/ab795a. 2. Xiang, Q.; Fan, L.; Li, Y.; Dong, S.; Li, K.; Bai, Y. A review on recent advances in plasma-activated water for food safety: current applications and future trends. Critical reviews in food science and nutrition 2022 , 62, 2250–2268. https://doi.org/10.1080/10408398 .2020.1852173. 3. Zhou, R.; Zhou, R.; Wang, P.; Xian, Y.; Mai-Prochnow, A.; Lu, X.; Cullen, P.J.; Ostrikov, K.; Bazaka, K. Plasma-activated water: generation, origin of reactive species and biological applications. Journal of Physics D: Applied Physics 2020 , 53, 303001. https://doi.org/10.1088/1361-6463/ab81cf. 4. Oh.; Szili.; Hatta.; Ito.; Shirafuji. Tailoring the Chemistry of Plasma-Activated Water Using a DC-Pulse-Driven Non-Thermal Atmospheric-Pressure Helium Plasma Jet. Plasma 2019, 2, 127–137. https://doi.org/10.3390/plasma2020010. 5. van Gils, C.A.J.; Hofmann, S.; Boekema, B.K.H.L.; Brandenburg, R.; Bruggeman, P.J. Mechanisms of bacterial inactivation in the liquid phase induced by a remote RF cold atmospheric pressure plasma jet. Journal of Physics D: Applied Physics 2013, 46, 175203. https://doi.org/10.1088/0022-3727/46/17/175203. 6. COMSOL Multiphysicsv. 6. www.comsol.com. COMSOL AB, Stockholm, Sweden

On the Temperature and Plasma Distribution of an Inductively Driven Xe-I2-Discharge

Inductively Coupled Plasma (ICP) discharges are part of intense research. Predicting different plasma parameters, like the distribution and temperature of the present species, is of great interest for many applications. Iodine- or halide-containing plasmas in particular have an important function, for example, in the development of mercury-free UV radiation sources. Therefore, a 2D simulation model of a xenon- and iodine-containing ICP was created by using the Finite Element Method (FEM) software COMSOL Multiphysics®. The included species and the used reactions are presented in this paper. To verify the simulation in relation to the plasma distribution, the results were compared with measurements from literature. The temperature of the lamp vessel was measured in relation to the temperature distribution and also compared with the results of the simulation. It could be shown that the simulation reproduces the plasma distribution with a maximal deviation of ≈6.5% to the measured values and that the temperature distribution in the examined area can be predicted with deviations of up to ≈24% for long vessel dimensions and ≈3% for shorter dimensions. However, despite the deviating absolute values, the general plasma behaviour is reproduced by the simulation. The simulation thus offers a fast and cost-effective method to estimate an effective geometrical range of iodine-containing ICPs

Medium Pressure Inductive Driven Lamps For UV- Water- Treatment

The use of UV-radiation from mercury plasmas is a common method for water disinfection. However, because of the toxicity of the mercury, the filling amount should be lowered or the mercury should be replaced [1]. Therefore, we developed medium pressure and inductively driven plasma lamps for UV generation, in an EU founded “Horizon2020” project. Since field effect transistors made of wide bandgap semiconductor materials like SiC and GaN are available, it is possible to build highly efficient inverters for powers ≥1 kW and frequency range up to 3 MHz [2]. Those frequencies can be used for an efficient operation of inductive plasmas [3]. Because in the inductive operation no electrodes are needed, it is possible to use lamp-filling materials, which would react in common lamps with the electrodes. The electrodeless operation opens the possibility to use a wide range of fillings to replace the mercury. Furthermore, in conventional lamps the electrodes are the most limiting factor for the lifetime of the lamps. In our work, we tested different lamp-fillings. Due to the required vapour pressures halides are preferred here. Furthermore, with regard to the heat distribution, radiation surface and the RF power coupling, the geometry of the lamp vessels were optimized. Therefore different dimensions were tested and the influences were monitored by temperature, current and radiation measurements. In addition, different coil geometries were simulated and tested to optimize the compromise between the radiation reducing coil shading and the needed field strength at a given current for the inductive operation. With our lamps, we reach efficiencies nearly in the range of standard medium pressure electrode lamps. The lifetime of electrodeless operation should be drastically higher. Therefore, the presented inductively driven UV-sources could provide a good alternative to conventional technologies. References : [1] Regulation (EU) 2017/852 of the European Parliament and of the Council of 17 May 2017 on mercury, and repealing Regulation (EC) No 1102/2008 [2] Denk et. Al. R DS(on) vs. Inductance Comparison of SiC MOSFETs in 7pin D2Pak and 4pin TO-247 and their benefits for high-power MHz. IET Power Electronics 2019 [3] Popov, O.A. Efficient Light Source Based on an Inductive Ferrite-Free Discharge at Frequencies of 300-3000kHz. Technical Physics 2007, 52, 751–758

High Dynamic Range Smart Window Display by Surface Hydrophilization and Inkjet Printing

Mechanoresponsive smart windows have been intensively investigated in recent years as they offer various applications for signage and light management. However, integrating a display functionality into such smart windows remains a challenge since the realization of pixels in these devices is difficult. In addition, mechanoresponsive smart windows with a high dynamic range are rarely demonstrated because they would suffer from complex fabrication processes and high costs. In this work, a novel surface modification process and digital encoding were developed for direct inkjet printing of micro-etching-masks on hydrophobic elastomers, and a pixelated haze distribution was realized. Compared to the traditional mechanoresponsive smart windows, which modify the optical performance by applied strain solely, here, a smart window with haze tunability in either static or strain-applied state is demonstrated. The work enhances the potential of the fabricated smart window to be applied in high dynamic range signage displays

Induktive UV-Strahler: Simulation und Vermessung

Bereits Ende des 19. Jahrhunderts wurden die ersten UV-Strahlungsquellen auf Quecksilberbasis vorgestellt [1]. Durch permanente Forschung konnte die Effizienz dieser Strahler zwar stetig verbessert werden, jedoch war es bisher nicht realisierbar, das giftige und umweltschädliche Quecksilber bei effizienten UVC-Erzeugung durch unbedenkliche Materialien zu ersetzen. Mitte der 2000er Jahre konnten durch die Entwicklung von Leistungstransistoren aus Siliciumcarbid (SiC) effiziente Vorschaltgeräte für Leistungen > 1 kW bei Frequenzen im MHz-Bereich realisiert werden [2]. Somit ergibt sich ein neuer Ansatz, um induktiv angeregte Strahlungsquellen zu betreiben. Die Leistungseinkopplung erfolgt bei der induktiven Entladung durch ein induziertes elektrisches Feld, welches durch ein hochfrequentes Magnetfeld in einer Spule erzeugt wird. Durch den elektrodenlosen Betrieb können jegliche Elektrodenreaktionen vernachlässigt werden. Dies eröffnet eine große Auswahl an möglichen Füllkomponenten um Quecksilber zu substituieren. So konnte am Lichttechnischen Institut des Karlsruher Instituts für Technologie ein quecksilberfreies System zur UV-Erzeugung entwickelt werden, welches die Effizienzen von konventionellen Quecksilberstrahlern erreicht [3]. Da es sich bei den entwickelten Strahlungsquellen um geschlossene Systeme handelt, ist das direkte vermessen der Plasma-parameter nicht möglich. Aus diesem Grund wurde ein Simulationsmodell in der FEM-Software COMSOL Multiphysics entwickelt, welches die grundlegenden Plasma-Parameter der Strahler wiedergibt [4]. Das Modell erlaubt das reale System mit verschiedenen Betriebsparametern abzubilden und wurde z.B. zur Untersuchung der Temperaturverteilungen verwendet. Des Weiteren kann die genannte Software auch genutzt werden um mittels Raytracing die Strahlungsverteilung des Systems zu bestimmen. Durch das Konzept der induktiven Entladung führt die Spulenabschattung zu einer inhomogenen Strahlungsverteilung. Die entwickelte Simulation hilft eine exaktere Effizienzbestimmung zu ermöglichen. Werden die entwickelten UV-Strahler im Bereich der Luftentkeimung eingesetzt, können die beschriebenen Simulationsmodelle auch zum Nachweis der Entkeimungswirksamkeit genutzt werden. In Verbindung mit einer gegebenen Reaktorgeometrie des Luftreinigers, Refelxionsgraden der verwendeten Materialien und der Vermessung der wirksamen UV-Bestrahlungsstärke an verschiedenen Punkten innerhalb des Systems ist beispielsweise der Nachweis der Entkeimungswirksamkeit durch validierte Simulation nach DIN/TS 67506:2022 möglich. [1] Circa 1903: Artefakte in der Gründungszeit des Deutschen Museums; Vol. N.F., 19, Abhandlungen und Berichte / Deutsches Museum, Deutsches Museum: München, 2003. [2] Raymond S. Pengelly, Simon M. Wood, James W. Milligan, Scott T. Sheppard, and William L. Pribble. A review of gan on sic high electron-mobility power transistors and mmics. IEEE Transactions on Microwave Theory and Techniques, 60(6):1764–1783, 2012. [3] Gehring, T. Induktiv angeregte quecksilberfreie Hochdruckplasmen für den Einsatz in UV-Desinfektionssystemen. Hochschulschrift, 2022. https://doi.org/10.5445/IR/1000149951. [4] COMSOL Multiphysics v. 6. www.comsol.com. COMSOL AB, Stockholm, Sweden