The operation of a single-electrode coaxial plasma gun

1968 ◽  
Vol 46 (18) ◽  
pp. 2055-2058 ◽  
Author(s):  
G. J. Pert
Keyword(s):  
High Speed ◽  
High Speed Photography ◽  
Central Electrode ◽  
Back Wall ◽  
Plasma Gun ◽  
Parametric Studies ◽  
Magnetic Probes

The operation of a coaxial-type plasma gun with the central electrode replaced by a pinched gas column was studied by high-speed photography and magnetic probes. It was found that the discharge was unstable after approximately 1.5 μs. and that the plasma slug was not accelerated by the current after this time. Parametric studies indicated that the plasma slug was contaminated with impurities from the insulating back wall of the device.

A Compact Plasma System for Experimental Study

2013 ◽  
Vol 278-280 ◽  
pp. 90-100 ◽  
Author(s):  
Gourishankar Sahoo ◽  
Rita Paikaray ◽  
Subrata Samantaray ◽  
Dheeren Chandra Patra ◽  
Narayan Chandra Sasini ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Speed ◽  
Ccd Camera ◽  
Diagnostic Tools ◽  
Plasma System ◽  
Pulse Delay ◽  
Plasma Gun ◽  
Pulse Forming Network ◽  
Digital Pulse ◽  
Magnetic Probes

A compact plasma system is set up at Ravenshaw University, India. The plasma system consists of a curved vacuum chamber which is nothing but a part of a toroid (θ=700) having minor radius, r= 0.3 m and major radius, R= 0.5 m, vacuum system, electromagnet, gas injected washer stacked plasma gun to produce plasma blobs/filaments, pulse forming network to energise plasma gun, diagnostic tools like electric probes, magnetic probes, spectrometer, high speed CCD camera, digital pulse/delay generator to synchronise the diagnostic tools. A pair of copper coil is wound over the chamber and capacitive pulse is fed to the coil to produce non-uniform magnetic field inside the chamber. The gas injected washer stacked plasma gun is a mono-anode - multi cathode system having five cathodes made up of brass and an anode made up of copper. The gun impedance is ~ 15 Ω. The pulse forming network (PFN) is Guillemin E type which consists of capacitors having equal capacitance 5.5 μF and inductors having equal inductances 1.5 μH. The pulse width of the PFN is ~ 7.6 μs for a seven stage network, as tested with known resistive circuit. Magnetic probes are designed and calibrated using a Helmholtz coil to map the radial magnetic field profile of the plasma chamber. Electric probes like Langmuir triple probe, velocity probes are designed to measure plasma parameters like blob velocity, density, temperature etc. Emission spectroscopy method is used to identify charged species inside the plasma. High speed CCD camera is used to interpret the structure of the plasma. A digital pulse/trigger generator is used to synchronise the CCD, spectrometer and switching thyristor etc. Preliminary results are also reported.

Crack divergence phenomena in tempered glass

2020 ◽  
Vol 13 (3) ◽  
pp. 115-129
Author(s):  
Shin’ichi Aratani
Keyword(s):  
Optimal Design ◽  
High Speed ◽  
Glass Plate ◽  
Acute Angle ◽  
Divergence Angle ◽  
High Speed Photography ◽  
Tempered Glass ◽  
Thick Glass

High speed photography using the Cranz-Schardin camera was performed to study the crack divergence and divergence angle in thermally tempered glass. A tempered 3.5 mm thick glass plate was used as a specimen. It was shown that two types of bifurcation and branching existed as the crack divergence. The divergence angle was smaller than the value calculated from the principle of optimal design and showed an acute angle.

Experimental study of hydrodynamic effects in the inverse water hydrocarbon emulsions flow in microchannels

2016 ◽  
Vol 11 (1) ◽  
pp. 30-37 ◽  
Author(s):  
A.A. Rakhimov ◽  
A.T. Akhmetov
Keyword(s):  
High Speed ◽  
Petroleum Industry ◽  
Chemical Compounds ◽  
High Viscosity ◽  
Blocking Effect ◽  
High Speed Photography ◽  
Simple Chemical ◽  
Reported Study ◽  
Dynamic Blocking ◽  
Hydrodynamic Effects

The paper presents results of hydrodynamic and rheological studies of the inverse water hydrocarbon emulsions. The success of the application of invert emulsions in the petroleum industry due, along with the high viscosity of the emulsion, greatly exceeding the viscosity of the carrier phase, the dynamic blocking effect, which consists in the fact that the rate of flow of emulsions in capillary structures and cracks falls with time to 3-4 orders, despite the permanent pressure drop. The reported study shows an increase in viscosity with increasing concentration or dispersion of emulsion. The increase in dispersion of w/o emulsion leads to an acceleration of the onset of dynamic blocking. The use of microfluidic devices, is made by soft photolithography, along with high-speed photography (10,000 frames/s), allowed us to see in the blocking condition the deformation of the microdroplets of water in inverse emulsion prepared from simple chemical compounds.

scholarly journals Prey Capturing Dynamics and Nanomechanically Graded Cutting Apparatus of Dragonfly Nymph

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 559
Author(s):  
Lakshminath Kundanati ◽  
Prashant Das ◽  
Nicola M. Pugno
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
High Speed ◽  
Prey Capture ◽  
High Speed Photography ◽  
Sensory Organs ◽  
Dragonfly Nymph ◽  
Drag Forces ◽  
Predatory Insects ◽  
Dragonfly Nymphs

Aquatic predatory insects, like the nymphs of a dragonfly, use rapid movements to catch their prey and it presents challenges in terms of movements due to drag forces. Dragonfly nymphs are known to be voracious predators with structures and movements that are yet to be fully understood. Thus, we examine two main mouthparts of the dragonfly nymph (Libellulidae: Insecta: Odonata) that are used in prey capturing and cutting the prey. To observe and analyze the preying mechanism under water, we used high-speed photography and, electron microscopy. The morphological details suggest that the prey-capturing labium is a complex grasping mechanism with additional sensory organs that serve some functionality. The time taken for the protraction and retraction of labium during prey capture was estimated to be 187 ± 54 ms, suggesting that these nymphs have a rapid prey mechanism. The Young’s modulus and hardness of the mandibles were estimated to be 9.1 ± 1.9 GPa and 0.85 ± 0.13 GPa, respectively. Such mechanical properties of the mandibles make them hard tools that can cut into the exoskeleton of the prey and also resistant to wear. Thus, studying such mechanisms with their sensory capabilities provides a unique opportunity to design and develop bioinspired underwater deployable mechanisms.

Droplet transfer behavior of narrow gap laser wire filling welding

2019 ◽  
Vol 33 (01n03) ◽  
pp. 1940045 ◽  
Author(s):  
Z. Zhang ◽  
R. Wang ◽  
G. Gou ◽  
H. Chen ◽  
W. Gao
Keyword(s):  
Welding Speed ◽  
High Speed ◽  
Transition Period ◽  
High Speed Photography ◽  
Narrow Gap ◽  
Droplet Transfer ◽  
Transfer Behavior ◽  
Feeding Speed ◽  
Wire Feeding ◽  
Droplet Transition

In this paper, we study the droplet transition behavior of narrow gap laser wire filling welding under the condition of changing welding speed and wire feeding speed, and it was observed by high-speed photography. It was found that with the increase of welding speed, the frequency of droplet transfer was reduced and the transition period was prolonged. With the increase of wire feeding speed, the wire was not fully melted and finally inserted into the molten pool.

Experimental Characterization of a Modified Airlift Pump

2014 ◽  
Author(s):  
Afshin Goharzadeh ◽  
Keegan Fernandes
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
High Speed ◽  
Water Flow Rate ◽  
High Speed Photography ◽  
Two Phase ◽  
Inner Diameter ◽  
Airlift Pump ◽  
Flow Map ◽  
Churn Flow

This paper presents an experimental investigation on a modified airlift pump. Experiments were undertaken as a function of air-water flow rate for two submergence ratios (ε=0.58 and 0.74), and two different riser geometries (i) straight pipe with a constant inner diameter of 19 mm and (ii) enlarged pipe with a sudden expanded diameter of 19 to 32 mm. These transparent vertical pipes, of 1 m length, were submerged in a transparent rectangular tank (0.45×0.45×1.1 m3). The compressed air was injected into the vertical pipe to lift the water from the reservoir. The flow map regime is established for both configurations and compared with previous studies. The two phase air-water flow structure at the expansion region is experimentally characterized. Pipeline geometry is found to have a significant influence on the output water flow rate. Using high speed photography and electrical conductivity probes, new flow regimes, such as “slug to churn” and “annular to churn” flow, are observed and their influence on the output water flow rate and efficiency are discussed. These experimental results provide fundamental insights into the physics of modified airlift pump.

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