Emissive probes

Sheehan, J. P.; Hershkowitz, N.

doi:10.1088/0963-0252/20/6/063001

Cited by 199 publications

(219 citation statements)

References 93 publications

(246 reference statements)

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“…1(b), changes with input RF power and gas pressure (not shown in the figure). The diffused plasma in the main experimental chamber is characterized thoroughly by different electrostatic probes namely, the single 42 and double 43 Langmuir probes and emissive probe 44 in a working range of RF power (4-10 W) at argon pressure p = 0.04 mbar. Plasma parameters traces along X and Y-axes for working discharge parameters are depicted in the Sec.IV.…”

Section: Experimental Setup and Diagnosticsmentioning

confidence: 99%

Experimental observation of self excited co-rotating multiple vortices in a dusty plasma with inhomogeneous plasma background

2017

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We report an experimental observation of multiple co-rotating vortices in a extended dust column in the background of non-uniform diffused plasma. Inductively coupled RF discharge is initiated in the background of argon gas in the source region which later found to diffuse in the main experimental chamber. A secondary DC glow discharge plasma is produced to introduce the dust particles into the plasma. These micron sized poly-disperse dust particles get charged in the plasma environment and transported by the ambipolar electric field of the diffused plasma and found to confine in the potential well, where the resultant electric field of the diffused plasma (ambipolar E-field) and glass wall charging (sheath E-field) hold the micron sized particles against the gravity. Multiple co-rotating (anti-clockwise) dust vortices are observed in the dust cloud for a particular discharge condition. The transition from multiple to single dust vortex is observed when input RF power is lowered. Occurrence of these vortices are explained on the basis of the charge gradient of dust particles which is orthogonal to the ion drag force. The charge gradient is a consequence of the plasma inhomogeneity along the dust cloud length. The detailed nature and the reason for multiple vortices are still under investigation through further experiments, however, preliminary qualitative understanding is discussed based on characteristic scale length of dust vortex. There is a characteristic size of the vortex in the dusty plasma so that multiple vortices is possible to form in the extended dusty plasma with inhomogeneous plasma background. The experimental results on the vortex motion of particles are compared with a theoretical model and found some agreement.

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Section: Experimental Setup and Diagnosticsmentioning

confidence: 99%

Experimental observation of self excited co-rotating multiple vortices in a dusty plasma with inhomogeneous plasma background

2017

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“…This device produces plasmas with electron densities of n e ~ 0.1-8 x 10 8 cirr 3 and electron temperatures between T e ~ 1-2 eV. The neutral gas pressures inside the vacuum chamber were in the range of 8 x 10~4 and 3 x 10~3 mBar of argon that were held constant by means of a Bronkhorst F-210C leak valve driven by the E7100 controller.…”

Section: Methodsmentioning

confidence: 99%

Emissive Langmuir probes in the strong emission regime for the determination of the plasma properties

Tierno

Doménech

Donoso

et al. 2012

2012 Abstracts IEEE International Conference on Plasma Science

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Abstract-The determination of the plasma potential V^i of unmagnetized plasmas by using the floating potential of emissive Langmuir probes operated in the strong emission regime is investigated. The experiments evidence that, for most cases, the electron thermionic emission is orders of magnitude larger than the plasma thermal electron current. The temperature-dependent floating potentials of negatively biased V p < V^i emissive probes are in agreement with the predictions of a simple phenomenological model that considers, in addition to the plasma electrons, an additional electron group that contributes to the probe current. The latter would be constituted by a fraction of the repelled electron thermionic current, which might return back to the probe with a different energy spectrum. Its origin would be a plasma potential well formed in the plasma sheath around the probe, acting as a virtual cathode or by collisions and electron thermalization processes. These results suggest that, for probe bias voltages close to the plasma potential V p ~ V^i, two electron populations coexist, i.e., the electrons from the plasma with temperature T e and a large group of returned thermionic electrons. These results question the theoretical possibility of measuring the electron temperature by using emissive probes biased to potentials V p < V^i.

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“…The simplest method, i.e., floating potential method (see ref. [30] and references therein), is followed to measure these potentials. The cold emissive probe acts as a single Langmuir probe and gives the floating potential (V f ) at zero emission current.…”

Section: Characterization Of Inductive Diffused Plasmamentioning

confidence: 99%

Transport and trapping of dust particles in a potential well created by inductively coupled diffused plasmas

Choudhary

Mukherjee

Bandyopadhyay

2016

Review of Scientific Instruments

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A versatile linear dusty (complex) plasma device is designed to study the transport and dynamical behavior of dust particles in a large volume. Diffused inductively coupled plasma is generated in the background of argon gas. A novel technique is used to introduce the dust particles in the main plasma by striking a secondary direct current (DC) glow discharge. These dust particles are found to get trapped in an electrostatic potential well which is formed due to the combination of the ambipolar electric field caused by diffusive plasma and the field produced by the charged glass wall of the vacuum chamber.According to the requirements, the volume of the dust cloud can be controlled very precisely by tuning the plasma and discharge parameters. The present device can be used to address the underlying physics behind the transport of dust particles, self -excited dust acoustic waves and instabilities. The detailed design of this device, plasma production and characterization, trapping and transport of the dust particle and some of the preliminary experimental results are presented.

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Emissive probes

Cited by 199 publications

References 93 publications

Experimental observation of self excited co-rotating multiple vortices in a dusty plasma with inhomogeneous plasma background

Experimental observation of self excited co-rotating multiple vortices in a dusty plasma with inhomogeneous plasma background

Emissive Langmuir probes in the strong emission regime for the determination of the plasma properties

Transport and trapping of dust particles in a potential well created by inductively coupled diffused plasmas

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