Die radiale und axiale Entwicklung des Leuchtens im Funkenkanal, untersucht mit einer Wischkamera

1967 ◽  
Vol 22 (7) ◽  
pp. 1089-1097 ◽  
Author(s):  
Jörn Koppitz
Keyword(s):  
Discharge Channel ◽  
Radial Expansion ◽  
Channel Radius ◽  
Hot Plasma ◽  
Spark Channel ◽  
Good Agreement ◽  
Axial Development

In this work the radial and axial development of the hot plasma spark channel is treated. The measured radial expansion is in good agreement with the theory of Braginskii, but not with that of Drabkina. A formula for the dependence of the channel radius on external parameters is derived. Axial inhomogeneities were found to be the consequence of an inhomogeneous development in the pre-discharge channel during the streamer stage.

Dynamic Fracture of 6061-T6 Aluminum Cylinders

1977 ◽  
Vol 44 (4) ◽  
pp. 643-646 ◽  
Author(s):  
D. L. Wesenberg ◽  
M. J. Sagartz
Keyword(s):  
Wave Propagation ◽  
Dynamic Fracture ◽  
Capacitor Bank ◽  
Magnetic Pressure ◽  
Strain Rates ◽  
Radial Expansion ◽  
Material Parameters ◽  
Subsequent Fracture ◽  
Thin Walled ◽  
Good Agreement

Radial expansion and subsequent fracture into segments of thin-walled cylindrical shells at large initial strain rates are studied analytically and experimentally. The theory of probability along with a description of relief wave propagation away from each fracture is used to formulate a theory which predicts the number of fractures and the distribution of fragment lengths. Eleven 6061-T6 Aluminum cylinders were expanded at strain rates of ∼104 s−1 by magnetic pressure pulses from a capacitor bank discharge, and these results are compared with predictions. Good agreement is shown between experimental results and predictions. In addition, the physical and material parameters to which the problem is sensitive are discussed.

The thickness of perpendicular collisionless shocks in a hot plasma

1972 ◽  
Vol 8 (2) ◽  
pp. 137-142 ◽  
Author(s):  
R. A. Cairns
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Wave Front ◽  
Characteristic Length ◽  
Magnetic Pressure ◽  
Collisionless Shocks ◽  
Hot Plasma ◽  
Shock Thickness ◽  
Good Agreement

By linearizing about the upstream state, the characteristic length for the growth of magnetic field in a laminar wave front, propagating perpendicular to an external magnetic field, is found as a function of βi, the ratio of ion pressure to magnetic pressure. For values of βi, between 10–2 and 1 the thickness is found to scale as . This scaling is in good agreement with the observed scaling of turbulent shocks, suggesting that for such shocks the shock thickness is closely related to that of the corresponding laminar pulse.

Investigation of the Dynamics of a Microstructured Spark Channel in Air in the “Tip (Anode)–Plane” Geometry at the Stage of Radial Expansion

2021 ◽  
Vol 47 (1) ◽  
pp. 73-79
Author(s):  
K. I. Almazova ◽  
A. N. Belonogov ◽  
V. V. Borovkov ◽  
V. S. Kurbanismailov ◽  
P. Kh. Omarova ◽  
...  
Keyword(s):  
Plane Geometry ◽  
Radial Expansion ◽  
Spark Channel ◽  
Anode Plane

Considerations on Spark- Gap Channel Radius and Electrical Conductivity

2020 ◽  
Vol 38 (3B) ◽  
pp. 168-176
Author(s):  
Bassam H. Habib
Keyword(s):  
Electrical Conductivity ◽  
Present Model ◽  
Temporal Evolution ◽  
Mathematical Formulation ◽  
Channel Radius ◽  
Spark Gap ◽  
Experimental Parameters ◽  
Constant Quantity ◽  
Spark Channel

A simple phenomenological model is established to determine the temporal evolution of spark gap channel radius and electrical conductivity during the resistive phase period. The present determination is based on the Braginskii’s equation for the channel radius which includes the electrical conductivity of the discharge channel as a constant quantity. In the present model, however, the electrical conductivity is regarded as a time varyingquantity. Basing on this, a mathematical formulation for the channel radius as a function of time was derived, and this has made possible the derivation of an explicit expression for the conductivity as a function of time as well. Taking the temporal average of the electrical conductivity offers an alternative mathematical formulation for the instantaneous radius based on a steady conductivity value that can be determined according to some experimental parameters. It has been verified that both of the channel radius formulations mentioned above lead to similar results for the temporal evolution. The obtained results of the channel radius were used to determine the instantaneous inductance of the spark channel. The present model was used to examine the role of gas pressure and gap width on the temporal evolutions of the channel radius, conductivity, and inductance in nanosecond spark gaps.

scholarly journals Simulation and experimental studies on the evolution of a laser spark in air

1992 ◽  
Vol 10 (4) ◽  
pp. 707-713 ◽  
Author(s):  
X. C. Zeng ◽  
D. P. Singh ◽  
V. Palleschi ◽  
A. Salvetti ◽  
M. De Rosa ◽  
...  
Keyword(s):  
Shock Waves ◽  
Experimental Studies ◽  
Numerical Code ◽  
Radiation Hydrodynamics ◽  
Theoretical Studies ◽  
Air Plasma ◽  
Hot Plasma ◽  
Laser Spark ◽  
Experimental And Theoretical Studies ◽  
Good Agreement

Experimental and theoretical studies on the evolution of shock waves in air plasma induced by laser spark have been carried out. The systematic study of the shock wave has been performed experimentally and 1-D numerical code of radiation hydrodynamics (1-DRHC) has been used to simulate the later stage of laser spark in air. The numerical results on the propagation of shock waves and the expansion of hot plasma are presented and subsequent results on the first divergent and convergent shock waves are found to be in good agreement with the experimental data.

Investigation of plasma properties in the phase of the radial expansion of spark channel in the pin-to-plate geometry

2020 ◽  
Author(s):  
Kseniya Igorevna Аlmazova ◽  
Artem Nikolaevich Belonogov ◽  
Valerii Viktorovich Borovkov ◽  
Zaira Rasulovna Khalikova ◽  
Gadjimirza Balaglanovich Ragimkhanov ◽  
...  
Keyword(s):  
Radial Expansion ◽  
Plasma Properties ◽  
Spark Channel ◽  
Plate Geometry

Design, Kinematics, and Application of Axially and Radially Expandable Modular Soft Pneumatic Actuators

2021 ◽  
pp. 1-14
Author(s):  
Nianfeng Wang ◽  
Bicheng Chen ◽  
Xiandong Ge ◽  
Xianmin Zhang ◽  
Wei Chen
Keyword(s):  
Modular Design ◽  
Virtual Work ◽  
Experimental Results ◽  
Pneumatic Actuator ◽  
Radial Expansion ◽  
Principle Of Virtual Work ◽  
Pneumatic Actuators ◽  
Axial Elongation ◽  
Yeoh Model ◽  
Good Agreement

Abstract Recently, soft pneumatic actuators (SPAs) have drawn increasing attention due to their ease of fabrication, high customizability and innately softness. Inspired by modular design, two kinds of SPAs including an axial elongation soft pneumatic actuator (aeSPA) and a radial expansion soft pneumatic actuator (reSPA) are proposed in this paper, followed by their modeling, fabrication, and application in locomotion robots. The relationships between pressure and displacement of these SPAs are deduced based on the Yeoh model and the principle of virtual work, which has a good agreement with experimental results. Five modular worm-like crawling robots are fabricated by assembling the aeSPAs and reSPAs in different morphology, and crawling tests are performed under different conditions to show the adaptivity of robots.

scholarly journals Numerical simulation of gap length influence on energy deposition in spark discharge

2021 ◽  
pp. 35-43
Author(s):  
K.V. Korytchenko ◽  
O.V. Shypul ◽  
D. Samoilenko ◽  
I.S. Varshamova ◽  
А.A. Lisniak ◽  
...  
Keyword(s):  
Total Energy ◽  
Linear Relationship ◽  
Discharge Current ◽  
Energy Input ◽  
Discharge Channel ◽  
Spark Discharge ◽  
Gas Dynamic ◽  
Spark Gap ◽  
Deposited Energy ◽  
Spark Channel

The aim of the work is to study the influence of the length of the spark gap on energy input into the discharge channel during its gas-dynamic expansion. Methodology. The research is carried out by numerical modeling of the process of spark discharge development at variable values of the discharge gap length and at invariable other discharge conditions. The length of the gap was set in the range from 1 mm to 20 mm. The study was conducted using a numerical model of spark development, which takes into account the processes of nonstationary gas-dynamic expansion of the spark channel, the transient process in the electric circuit, nonequilibrium chemical processes, gas ionization, heat transfer and electrons thermal conductivity. The simulation was performed in atmospheric pressure nitrogen. The calculation was performed for various parameters of the RLC circuit, such as capacitance, inductance, resistance and voltage across the capacitor. Results. The study evaluates the influence of the spark length on the discharge current, the resistance of the spark channel, the energy deposited in the spark channel, and the distribution of thermodynamic parameters of the gas during the development of the spark discharge. It is confirmed that increasing the length of the gap increases the resistance of the spark. The deviation from the linear relationship between the deposited energy or the radiated energy and the length of the spark gap is estimated. Scientific novelty. A linear relationship between the gap length and the deposited energy is revealed when the total energy is above tens of Joules. Deviations from the linear dependence were detected in the discharge circuit when the total energy is below one of Joules. Practical value. The research results allow predicting the effect of the spark gap length on the energy input into the discharge channel under conditions of a slight change in the discharge current. In the conditions of essential change of amplitude of discharge current it is expedient to apply numerical researches for specification of changes in the energy deposited into a spark discharge.

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