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Micro-Hollow Cathode Discharge Plasma Jet

Mentors: Dr. WeiDong Zhu Dr. Jose Lopez Members Working: Anthony DeCaro Gagan Sapkota Joseph Jordan Viviana Alvitres. Micro-Hollow Cathode Discharge Plasma Jet. Well, what is micro-hollow cathode discharge???.

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Micro-Hollow Cathode Discharge Plasma Jet

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  1. Mentors: Dr. WeiDong Zhu Dr. Jose Lopez Members Working: Anthony DeCaro Gagan Sapkota Joseph Jordan VivianaAlvitres Micro-Hollow Cathode DischargePlasma Jet

  2. Well, what is micro-hollow cathode discharge??? • Micro-hollow cathode discharge (Plasma torch)got its name from its configuration which uses micro-hollow cylindrical copper tube as its cathode • Gas flows through the tube which becomes plasma when high voltage is applied and the gas thrusts out as a plume, which is called plasma jet or plasma plume /Gas

  3. What are we doing with plasma torch? • Gas which is flowed from the micro-hollow cathode can be altered and the properties of plasma generated by different gases can be studied so as to identify the active species, free radicals or any components present (BUT WHY?) • We are using combination of Helium gas (98% ) and oxygen gas (2% ) and trying to identify the composition of the plasma thus generated

  4. Experimental Set-up • Plasma Torch - The major device with which the plasma plume is created by applying high voltage to the cathode and flowing the gas through it • Power Supply – Of course to supply power! Using this device we can start the device supplying enough voltage for the breakdown of the gas and control the amount of current supplied to the device after it is started • Gas Tanks – The source of the helium and oxygen used for our experiment. • Flow Regulators – The devices used to control the amount of gas used in the torch i.e. 98% Helium and 2% oxygen. • Spectrometer – The optical device which gathers the light emission from the plasma, turns into an electric signal and gives the wavelength of the light received from the plasma.

  5. Schematic Representation of the Experiment Step 2 Step 1 Step 4 He O2 -475.8 -20.0 Step 3

  6. What have we done so far? • Extracted the emission spectrum of the plasma from 250-800 nm for different currents • 20 mA • 25 mA • 35 mA • Placed the plasma torch in water and studied the spectrum of the plasma inside water • With a glass barrier between plasma and the spectrometer fiber • Without any barrier (head-on spectroscopy of the plasma in water) • Identified the corresponding elements or radicals indicated by the peaks on the spectrum obtained • Currently, we are studying the best possible combination ration for Helium and oxygen gas so as to optimize the level of oxygen emission

  7. Spectrum of Plasma in Air, 20 mA

  8. Spectrum of Plasma in Air, 25 mA

  9. Spectrum of Plasma in Air, 35 mA

  10. Spectrum of Plasma in Water, 20 mA

  11. What have we found? Peaks at the following wavelengths were observed in air: 777.3 nm , 728.4 nm, 706. 7 nm, 667.6 nm, 615.4 nm 587.4 nm, 501.3 nm, 491.7 nm, 462.8 nm, 439.1 nm These peaks were identified to be of Oxygen and helium!!! Peaks at the following wavelength were observed in water: 777.3 nm , 728.4 nm, 706. 7 nm, 667.6 nm, 615.4 nm 587.4 nm, 501.3 nm, 491.7 nm, 462.8 nm, 439.1 nm

  12. What can be done next? • Concentration of the hydroxide generated by the plasma in water can be measured to study the conditions which can optimize the production of OH ions. • Study of OH ions is important because of the important role of OH ions in disinfecting the bacteria. OH ions can easily enter the lipid cellular layer, which is basically made up of unsaturated hydrocarbon. Because of the role of OH in killing cells, optimization of OH ions is of great significance. • The next thing that can be done is to generate cold plasma with room temperature, as the temperature of the plasma in our lab is way much higher than the room temperature. For this, a pulsed DC supply can be used to generate short (50-100 ns) pulse, which won’t heat the gas as does the constant power supply. • We are also in the process of measuring the hydrogen peroxide production as a result of the reaction the torch has with the water that it is submerged in while testing. Titration is used to determine how much of the substance is created.

  13. Why are we doing this? • Plasma has been known as powerful agent to kill bacteria and destroy biofilms • Presence of active species, high-electron temperature, ultravoilet rays makes plasma very effective material in biomedicine • Recently, plasma torch has been introduced to treat root canal infection, open wounds and destroy surface germs.

  14. The more I know, the more confused I get!!!

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