Control system for maintaining a Langmuir probe at plasma potential

1977 ◽  
Vol 48 (9) ◽  
pp. 1174-1178 ◽  
Author(s):  
J. L. Michau
Keyword(s):  
Control System ◽  
Langmuir Probe ◽  
Plasma Potential

Targeting Protective Catalase of Tumor Cells with Cold Atmospheric Plasma- Activated Medium (PAM)

2018 ◽  
Vol 18 (6) ◽  
pp. 784-804 ◽  
Author(s):  
Georg Bauer
Keyword(s):  
Control System ◽  
Singlet Oxygen ◽  
Tumor Cells ◽  
Plasma Potential ◽  
Atmospheric Plasma ◽  
Antitumor Action ◽  
Active Principle ◽  
Reaction Products ◽  
Cold Atmospheric Plasma

Background: Application of cold atmospheric plasma to medium generates “plasma-activated medium” that induces apoptosis selectively in tumor cells and that has an antitumor effect in vivo. The underlying mechanisms are not well understood. Objective: Elucidation of potential chemical interactions within plasma-activated medium and of reactions of medium components with specific target structures of tumor cells should allow to define the active principle in plasma activated medium. Methods: Established knowledge of intercellular apoptosis-inducing reactive oxygen/nitrogen species-dependent signaling and its control by membrane-associated catalase and SOD was reviewed. Model experiments using extracellular singlet oxygen were analyzed with respect to catalase inactivation and their relevance for the antitumor action of cold atmospheric plasma. Potential interactions of this tumor cell-specific control system with components of plasma-activated medium or its reaction products were discussed within the scope of the reviewed signaling principles. Results: None of the long-lived species found in plasma-activated medium, such as nitrite and H2O2, nor OCl- or .NO seemed to have the potential to interfere with catalase-dependent control of apoptosis-inducing signaling of tumor cells when acting alone. However, the combination of H2O2 and nitrite might generate peroxynitrite. The protonation of peroxnitrite to peroxynitrous acid allows for the generation of hydroxyl radicals that react with H2O2, leading to the formation of hydroperoxide radicals. These allow for singlet oxygen generation and inactivation of membrane-associated catalase through an autoamplificatory mechanism, followed by intercellular apoptosis-inducing signaling. Conclusion: Nitrite and H2O2 in plasma-activated medium establish singlet oxygen-dependent interference selectively with the control system of tumor cells.

Helicon Plasma Discharge for Processing Wall Material

2014 ◽  
Vol 513-517 ◽  
pp. 28-32
Author(s):  
T.Y. Huang ◽  
C.G. Jin ◽  
M.Z. Wu ◽  
L.J. Zhuge ◽  
X.M. Wu
Keyword(s):  
Magnetic Field ◽  
Electron Density ◽  
Langmuir Probe ◽  
Plasma Processing ◽  
Plasma Potential ◽  
Graphite Surface ◽  
Wall Material ◽  
Helicon Plasma ◽  
Helicon Wave ◽  
Ar Gas

A helicon wave plasma (HWP) discharge with strong magnetic field was investigated. The HWP was produced with an internal Nagoya III antenna that is perpendicular to the magnetic field and driven by a 13.56 MHz radio-frequency (RF) source. HWP was characterized in terms of electron density, electron temperature and plasma potential using a single Langmuir probe in Ar gas. The result of Langmuir probe shows that the electron density increases with RF power, but saturate above 700 W at a density of 2×1019m-3. Scanning electron microscopy (SEM) was extensively used to characterize the quality of the graphite surface. The result of SEM shows the surface of graphite that exposed to plasma processing has exhibited smoother and compacter surface topography. Meanwhile, the concentration of impurity on the graphite surface decreases with plasma processing.

scholarly journals Comparative measurement of plasma potential with tube probe and Langmuir probe

AIP Advances ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 115024
Author(s):  
Jian-quan Li ◽  
Wen-qi Lu ◽  
Jun Xu ◽  
Fei Gao ◽  
You-nian Wang
Keyword(s):  
Langmuir Probe ◽  
Plasma Potential ◽  
Comparative Measurement

Langmuir Probe Evaluation of the Plasma Potential in Tokamak Edge Plasma for Non-Maxwellian EEDF

2014 ◽  
Vol 54 (3) ◽  
pp. 267-272 ◽  
Author(s):  
Tsv. K. Popov ◽  
M. Dimitrova ◽  
P. Ivanova ◽  
E. Hasan ◽  
J. Horáček ◽  
...  
Keyword(s):  
Langmuir Probe ◽  
Plasma Potential ◽  
Edge Plasma ◽  
Tokamak Edge

scholarly journals CURRENT VOLTAGE CHARACTERISTIC OF PLANAR LANGMUIR PROBE IN IONOSPHERIC MAXWELLIAN PLASMA

2017 ◽  
Vol 5 (4) ◽  
pp. 228-237
Author(s):  
Shankar Bhattarai ◽  
Lekha Nath Mishra
Keyword(s):  
Langmuir Probe ◽  
Plasma Potential ◽  
Plasma Diagnostic ◽  
Langmuir Probes ◽  
Sounding Rockets ◽  
Maxwellian Plasma ◽  
Internal Parameters ◽  
Current Voltage ◽  
Probe Voltage ◽  
Plasma Characterization

Frequently used geometries of Langmuir probes are planar, spherical, and cylindrical shapes. The geometry is chosen depending on the purpose of the measurements and the platform configuration. Planar Langmuir Probes have been installed on satellites and sounding rockets to observe the general characteristics of thermal plasma in the ionosphere for more than five decades. Because of its simplicity and convenience, the Langmuir probe is one of the most frequently installed scientific instruments on spacecraft. The Planar Langmuir Probe is the key plasma diagnostic used by scientists interested in plasma characterization to measure the internal parameters of the bulk of the plasma. This research explores the theoretical study of Planar Langmuir Probe I-V Characteristics. The relationship between first derivative of current verses applied probe voltage is also computed. With the help of the (volt–ampere curves) of Planar Langmuir probes, the different parameters of plasma can be determined such as plasma potential, floating potential, probe currents in different probe voltage and so on. Planar Langmuir probe geometry is easy to construct and equally suitable for plasma characterization.

Methods for the Numerical Calculation of the Plasma Potential from Measured Langmuir Probe Characteristics

1986 ◽  
Vol 26 (4) ◽  
pp. 237-253 ◽  
Author(s):  
W. Seifert ◽  
D. Johanning ◽  
H.-R. Lehmann ◽  
N. Bankov
Keyword(s):  
Numerical Calculation ◽  
Langmuir Probe ◽  
Plasma Potential

Direct Plasma Potential Measurements by Ball-Pen Probe and Self-Emitting Langmuir Probe on COMPASS and ASDEX Upgrade

2014 ◽  
Vol 54 (3) ◽  
pp. 279-284 ◽  
Author(s):  
J. Adamek ◽  
J. Horacek ◽  
J. Seidl ◽  
H. W. Müller ◽  
R. Schrittwieser ◽  
...  
Keyword(s):  
Langmuir Probe ◽  
Plasma Potential
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