China
Africa
Explore chapters and articles related to this topic
On the Effect of Base Pressure Upon Plasma Containment
Published in B. Raneesh, Nandakumar Kalarikkal, Jemy James, Anju K. Nair, Plasma and Fusion Science, 2018
G. Sahoo, R. Paikaray, S. Samantaray, P. Das, J. Ghosh, A. Sanyasi
The experimental set up for plasma experiments at Ravenshaw University, i.e., compact plasma system (CPS) [20] consists of plasma chamber, pulse forming network (PFN) [21], plasma gun, gas feed system, diagnostic tools, data acquisition system, and data analysis software. The plasma chamber, under discussion is having major radius 50 cm and minor radius 30 cm. The PFN is capable of producing square wave pulse ~140 ps. By changing the stages of PFN the pulse width can be changed. The gas fed system is designed to maintain desired base/background/ambient pressure in the plasma chamber. Langmuir probe, emission spectroscopy technique and fast imaging were carried out for plasma diagnostics. The schematic diagram of the setup is given in Figure 7.1.
Spark Plasma Diagnostics
Published in Andreas Schmidt-Ott, Spark Ablation, 2019
Attila Kohut, Gábor Galbács, Zsolt Geretovszky
The overall objective of plasma diagnostics is to obtain information about key physical plasma parameters and the concentration of species, as well as their spatial profiles and dynamics—or plasma properties for short. Consequently, plasma modeling and diagnostic calculations work with a range of parameters, distributions, and profiles, such as temperature, pressure, magnetic and electric field strengths, particle fluxes, concentration of particles, etc. Technically speaking, of course there is no universal technique that could provide all this information; therefore a pool of methods is employed, and their output information is combined. The choice of the employed methods is made also with regard to the type of plasma and the invasiveness of the method [21–24].
Nanosecond Laser Ablation and Processing of Solid Targets in Vacuum or in a Low-Gas Atmosphere
Published in Ion N. Mihailescu, Anna Paola Caricato, Pulsed Laser Ablation, 2018
Vincenzo Resta, Ramón J. Peláez, Anna Paola Caricato
The analysis of the traveling species inside the plasma plume can be carried out with different characterization techniques, depending on the species to be analyzed. For electron and/or ion distribution, the plasma diagnostic can be done by means of Langmuir probe (LP) measurements, with a small biased metallic electrode placed inside the plasma. Depending on the applied bias, positive or negative, LP collects electrons (electron saturation region) or positively charged ions (ion saturation region), respectively. The ion current density transient, f(t), is defined as [22] () f(t)=I(t)RSe under the assumption that ions are single-ionized, where I(t) is the current transient, R the circuit resistance, S the LP surface, and e the charge of the electron. The total number of ions per unit area per pulse, that is, the ion yield, is obtained by time integration of f(t). The distribution of the ions can be obtained by assuming the laser plasma as an instantaneous point source of ions and approximating the ion velocity to as v = d/t, where t is the time delay with respect to the laser pulse and d the target-to-probe distance.
Preliminary Design of ITER Divertor Langmuir Probe System
Published in Fusion Science and Technology, 2020
Wei Zhao, Yali Wang, Yuzhong Jin, Li Zhao, Hongxia Zhou, Lin Nie, Guangwu Zhong, Chunjia Liu, Christopher Watts, James Paul Gunn
Langmuir probes, or electrostatic probes, are the first plasma diagnostic and were developed by Langmuir in the 1920s. The principle is relatively simple: A conductor in contact with the plasma is biased with a voltage V relative to the local plasma potential. The current I drawn by the probe is proportional to the local plasma density and temperature and in the simplest approximation is