Measuring the electron density in an Extreme Ultra-Violet generated plasma

In order to meet the demand of increasing computer speed and memory capacity, industries are striving to reduce the size of computer chips. This miniaturization of computer chips can be achieved by reducing the wavelength in lithography machines to Extreme Ultra-Violet (EUV, 92 eV). The low-pressure (around 1 Pa) transparent background gas (e.g. H¬2 and He) in the lithography machine is partially ionized by the absorption of EUV photons. The study of these low-density (1015 m-3) pulsed plasmas is interesting and experimentally challenging. Two different diagnostics are investigated to determine the electron density in these EUV-generated plasmas: coherent microwave scattering (CMS) and microwave cavity resonance spectroscopy (MCRS). CMS is based on the scattering of microwaves off the plasma, the scattered power has a resonance at the plasma frequency. In MCRS measurements the resonance frequency in a cavity is determined, this frequency depends on the electron density in the cavity. These two diagnostics are tested on a simulation plasma with similar dimensions and density as the EUV plasma. The results of MCRS on the simulation plasma show a detection limit of 1014 m-3 and a time-resolution of 16 ns. Currently a new setup is built to measure the electron density in the EUV plasma

Dust particle formation in argon-acetylene plasmas and interaction with (extreme) ultraviolet radiation

In extreme ultraviolet (EUV) lithography, ionic and particulate debris coming from the plasma source plays an important role. We started up a project looking more fundamentally at particulate formation in plasmas and the interaction with EUV radiation. To this end, we study a capacitively-coupled radio-frequency (13.56 MHz) argon-acetylene plasma. In low-pressure hydrocarbon plasmas dust particles spontaneously form under certain conditions. The whole process occurs in a matter of seconds to minutes after igniting the plasma and results in a cloud of particulates up to micrometer sizes levitating in the plasma. Our aluminum cylindrical discharge chamber also serves as a resonant cavity for low-power microwave (2 – 8 GHz) signals. The frequency at which resonance occurs is a measure for the free-electron density of the plasma. We present preliminary results on the temporal evolution of the electron density during dust particle formation up to several minutes after plasma ignition. Furthermore, we present an overview of approaches for future research predominantly aimed at the interactions in a more EUV-like environment

Conical Diffraction and Composite Lieb Bosons in Photonic Lattices

Pseudospin describes how waves are distributed between different “internal” degrees of freedom or microscopic states, such as polarizations, sublattices, or layers. Here, we experimentally demonstrate and explain wave dynamics in a photonic Lieb lattice, which hosts an integer pseudospin s=1 conical intersection. We study the most striking differences displayed by integer pseudospin states: pseudospin-dependent conical diffraction and the generation of higher charged optical vortices

Plasma accumulation effects in Extreme Ultra-Violet generated plasmas

In order to meet the demand of increasing computer speed and memory capacity, industries are striving to reduce the size of computer chips. This miniaturization can be achieved by reducing the wavelength in lithography machines to Extreme Ultra-Violet (EUV, 92 eV). The low-pressure (around 1 Pa) transparent background gas (e.g. H2 and He) in the lithography machine is partially ionized by the absorption of EUV photons. The study of these low-density 1E15 m^-3 pulsed plasmas is interesting and experimentally challenging. The electron density is measured with microwave cavity resonance spectroscopy (MCRS). In MCRS measurements the resonance frequency in a cavity is determined, this frequency depends on the electron density in the cavity. In this research the plasma accumulation is studied in an EUV-generated plasma in argon. The EUV source generates EUV pulses with a repetition frequency between 500 Hz and 10 kHz. The accumulation of plasma is clearly observed at frequencies above 1 kHz

The energy balance of Hg-free HID lamps and the influence of electrode distance

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Non-Steroidal Anti-inflammatory Drugs As Host-Directed Therapy for Tuberculosis: A Systematic Review

Lengthy, antimicrobial therapy targeting the pathogen is the mainstay of conventional tuberculosis treatment, complicated by emerging drug resistances. Host-directed therapies, including non-steroidal anti-inflammatory drugs (NSAIDs), in contrast, target host factors to mitigate disease severity. In the present Systematic Review, we investigate whether NSAIDs display any effects as therapy of TB and discuss possible mechanisms of action of NSAIDs as adjunctive therapy of TB. Ten studies, seven preclinical studies in mice and three clinical trials, were included and systematically reviewed. Our results point toward a beneficial effect of NSAIDs as adjunct to current TB therapy regimens, mediated by decreased lung pathology balancing host-immune reaction. The determination of the best timing for their administration in order to obtain the potential beneficial effects needs further investigation. Even if the preclinical evidence requires clinical evaluation, NSAIDs might represent a potential safe, simple, and cheap improvement in therapy of TB

Concepts and characteristics of the 'COST Reference Microplasma Jet'

Biomedical applications of non-equilibrium atmospheric pressure plasmas have attracted intense interest in the past few years. Many plasma sources of diverse design have been proposed for these applications, but the relationship between source characteristics and application performance is not well-understood, and indeed many sources are poorly characterized. This circumstance is an impediment to progress in application development. A reference source with well-understood and highly reproducible characteristics may be an important tool in this context. Researchers around the world should be able to compare the characteristics of their own sources and also their results with this device. In this paper, we describe such a reference source, developed from the simple and robust micro-scaled atmospheric pressure plasma jet (μ-APPJ) concept. This development occurred under the auspices of COST Action MP1101 'Biomedical Applications of Atmospheric Pressure Plasmas'. Gas contamination and power measurement are shown to be major causes of irreproducible results in earlier source designs. These problems are resolved in the reference source by refinement of the mechanical and electrical design and by specifying an operating protocol. These measures are shown to be absolutely necessary for reproducible operation. They include the integration of current and voltage probes into the jet. The usual combination of matching unit and power supply is replaced by an integrated LC power coupling circuit and a 5 W single frequency generator. The design specification and operating protocol for the reference source are being made freely available