Low-pressure sustainment of surface-wave microwave plasma with modified microwave coupler

Demand for food quality and extended freshness without the use of harmful chemicals has become a major topic over the last decade. New technologies are using UV light, strong electric field, ozone and other reactive agents to decontaminate food surfaces. The low-power non-equilibrium (cold) atmospheric pressure operating plasmas effectively combines all the qualities mentioned above and thus, due to their synergetic influence, promising results in fruit surface decontamination can be obtained. The present paper focuses on the applicability of the recently developed microwave surface wave sustained plasma torch for the treatment of selected small fruit. Optical emission spectroscopy is used for the determination of plasma active particles (radicals, UV light) and plasma parameters during the fruit treatment. The infrared camera images confirm low and fully applicable heating of the treated surface that ensures no fruit quality changes. The detailed study shows that the efficiency of the microbial decontamination of selected fruits naturally contaminated by microorganisms is strongly dependent on the fruit surface shape. The decontamination of the rough strawberry surface seems inefficient using the current configuration, but for smooth berries promising results were obtained. Finally, antioxidant activity measurements demonstrate no changes due to plasma treatment. The results confirm that the MW surface wave sustained discharge is applicable to fruit surface decontamination.

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THE OPTICAL PROPERTIES OF NITROGENATED AMORPHOUS CARBON FILMS GROWN BY A NOVEL SURFACE WAVE MICROWAVE PLASMA CVD METHOD

Modern Physics Letters B ◽

10.1142/s0217984904007529 ◽

2004 ◽

Vol 18 (18) ◽

pp. 987-1001 ◽

Cited By ~ 9

Author(s):

M. RUSOP ◽

S. ADHIKARI ◽

A. M. M. OMER ◽

S. ADHIKARY ◽

H. UCHIDA ◽

...

Keyword(s):

Optical Properties ◽

Surface Wave ◽

Amorphous Carbon ◽

Annealing Temperature ◽

Microwave Plasma ◽

Chemical Vapor ◽

Carbon Films ◽

Cvd Method ◽

Wide Range ◽

Bonding Properties

The effects of annealing temperature on the optical properties of nitrogenated amorphous carbon (a-C:N) films grown on quartz substrates by a novel surface wave microwave plasma chemical vapor deposition (SWMP-CVD) method are reported. The thickness, optical, structural and bonding properties of the as-grown and anneal-treated a-C:N films were measured and compared. The film thickness decreased rapidly with increasing annealing temperature above 350°C. A wide range of optical absorption characteristics is observed, depending on the annealing temperature. The optical band gap of as-grown a-C:N films is approximately 2.8 eV, gradually decreasing to 2.5 eV for the films anneal-treated at 300°C, and beyond that decreasing rapidly down to 0.9 eV at 500°C. The Raman and FTIR spectroscopy measurements have shown that the structural and composition of the films can be tuned by optimizing the annealing temperature. The change of optical, structural and bonding properties of SWMP-CVD-grown a-C:N films with higher annealing temperature was attributed to the fundamental changes in the bonding and band structures of the films.

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Numerical Investigation of the Surface Wave Formation in a Microwave Plasma Torch

IEEE Transactions on Plasma Science ◽

10.1109/tps.2017.2759501 ◽

2017 ◽

Vol 45 (11) ◽

pp. 2929-2939 ◽

Cited By ~ 6

Author(s):

Wencong Zhang ◽

Junwu Tao ◽

Kama Huang ◽

Li Wu

Keyword(s):

Surface Wave ◽

Numerical Investigation ◽

Plasma Torch ◽

Microwave Plasma ◽

Wave Formation ◽

Microwave Plasma Torch

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A two-step modelling approach for plasma reactors – experimental validation for CO2 dissociation in surface wave microwave plasma

Reaction Chemistry & Engineering ◽

10.1039/c9re00022d ◽

2019 ◽

Vol 4 (7) ◽

pp. 1253-1269 ◽

Cited By ~ 6

Author(s):

Sergio H. Moreno ◽

Andrzej I. Stankiewicz ◽

Georgios D. Stefanidis

Keyword(s):

Surface Wave ◽

Performance Analysis ◽

Experimental Validation ◽

Microwave Plasma ◽

Second Step ◽

Plasma Reactors ◽

Plasma Model ◽

Self Consistent ◽

Modelling Approach

Modelling approach that comprises a 2D self-consistent plasma model for discharge characterization in the first step and a 0D global plasma model for performance analysis in the second step.

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BAND GAP SHIFT DUE TO NITROGEN DOPING, COMPOSITION GAS PRESSURE AND MICROWAVE POWER OF a-C:N THIN FILMS GROWN BY NEWLY-DEVELOPED SURFACE WAVE MICROWAVE PLASMA CVD

Surface Review and Letters ◽

10.1142/s0218625x04006529 ◽

2004 ◽

Vol 11 (06) ◽

pp. 559-562

Author(s):

M. RUSOP ◽

S. ADHIKARI ◽

A. M. M. OMER ◽

S. ADHIKARY ◽

H. UCHIDA ◽

...

Keyword(s):

Thin Films ◽

Surface Wave ◽

Film Thickness ◽

Band Gap ◽

Microwave Power ◽

Annealing Temperature ◽

Optical Band Gap ◽

Microwave Plasma ◽

Gas Pressure ◽

Developed Surface

This paper reports the band gap shifting due to nitrogen ( N 2) doping, microwave power and composition gas pressure of nitrogenated amorphous carbon ( a - C : N ) thin films deposited by newly-developed surface wave microwave plasma chemical vapor deposition (SWMP-CVD). Results show that the optical band gap decreased from 4.1 eV to 2.4 eV corresponding to the increase of N 2 doping from 0 to 5% in the gas ratio. However, further increase of N 2 doping beyond 5% did not decrease the band gap. It was found that composition gas pressure and launched MW power during film deposition also largely control the optical band gap. Investigation of annealing effects on optical band gap and film thickness of the N 2 doped films revealed that both band gap and film thickness decrease significantly with increase of annealing temperature. The optical band gap decreased from 2.4 eV to 1.1 eV, while film thickness decreases from 320 nm to 50 nm corresponding to 200 to 400°C annealing temperature. The results revealed that the properties of a - C : N can be tuned by changing the annealing temperature, composition gas pressure and microwave power of the SWMP-CVD system.

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