Kyushu Univ. Department of Advanced Energy Engineering Science Interdisciplinary Graduate School of Engineering Sciences/ Kyushu Univ. Faculty of Engineering Development of Energy Sciences and Engineering
Advanced Space Propulsion Laboratory(Yamamoto Lab)
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Plasma Application & Diagnostics

Ball lightning

Ball lightning is an atmosphere pressure plasma and generated by discharge of high voltage on the surface of an electrolyte. Ball lightinig is a long lived plasmoid compared to the energy input period.Ball lightning plasma produces OH and O radicals and these radicals will oxidize and dispose PM2.5.These characteristics should be suitable for PM2.5 removal devices.
The physical properties of Ball lighting have not been elucidated even now. Therefore, we estimate the temperature of FB using various diagnositics(emission spectroscopy and laser diagnositics) and to demonstrate decomposing PM2.5 on a filter.
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cBN field emission cathode

Ball lightning is an atmosphere pressure plasma and generated by discharge of high voltage on the surface of an electrolyte. Ball lightinig is a long lived plasmoid compared to the energy input period.Ball lightning plasma produces OH and O radicals and these radicals will oxidize and dispose PM2.5.These characteristics should be suitable for PM2.5 removal devices. The physical properties of Ball lighting have not been elucidated even now. Therefore, we estimate the temperature of FB using various diagnositics(emission spectroscopy and laser diagnositics) and to demonstrate decomposing PM2.5 on a filter.
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Cavity Ring-Down Spectroscopy (CRDS)

CRDS is a laser absorption spectroscopy that can accurately measure the density and velocity of a target sample. This method has been developed in fields such as molecular spectroscopy, atmospheric monitoring, combustion diagnosis, and plasma diagnosis. When the optical cavity is composed of two high-reflection mirrors (reflectance> 99% or more) as shown in the figure on the right, the trapped light repeats reflection while attenuating the intensity little by little at each reflection. Since some light passes through the mirror during reflection, this method measures the density and velocity of the substance inside the cavity by observing the attenuation of its intensity. If the reflectivity of the high-reflection mirror is 99.99%, for example, the optical path length will be 10,000 times and the sensitivity will be 10,000 times that of conventional absorption spectroscopy (absorbance is obtained as the product of the absorption coefficient and the optical path length). In addition, it has features such as the ability to measure the density of the ground state and no need for calibration to calculate the absolute density. The purpose of the Yamamoto Laboratory is to develop a system that can quantitatively evaluate durability in real time by measuring sputter particles emitted from electric propulsion systems using CRDS.
crds

Laser Thomson Scattering

 Laser Thomson scattering (LTS) technique is a laser based optical method for a measurement of plasma properties, such as electron number density (Ne) /electron temperature (Te). In the incoherent regime, the scattered spectrum reflects the Doppler motion of individual electrons, and the scattered intensity is proportional to Ne. This method was developed to measure plasma properties in high temperature plasma having Ne > 1019 m-3. During the last decade, its applicability has been extended to lower density plasma, with densities of less than 1016 m-3, by a signal accumulation technique.10 This technique allows us to apply LTS to the plasma in the discharge chamber of a miniature microwave ion thruster and our previous study showed that LTS technique was useful and validate tool for the measurement of plasma property.
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