Probing astrophysical jet formation in the laboratory

Scilight ◽  
2021 ◽  
Vol 2021 (18) ◽  
pp. 181105
Author(s):  
Alane Lim
Keyword(s):  
Jet Formation ◽  
Astrophysical Jet

scholarly journals Modeling of supersonic jet formation in conical wire array Z-pinches

2002 ◽  
Vol 20 (2) ◽  
pp. 255-261 ◽  
Author(s):  
A. CIARDI ◽  
S.V. LEBEDEV ◽  
J.P. CHITTENDEN ◽  
S.N. BLAND
Keyword(s):  
Mach Number ◽  
Wire Array ◽  
Supersonic Jet ◽  
Thermal Gradients ◽  
Jet Formation ◽  
Wire Arrays ◽  
Astrophysical Jet ◽  
Conical Shock ◽  
High Mach ◽  
Jet Collimation

Supersonic jet production in conical wire array Z-pinches is modeled using a two-dimensional (2D) resistive magneto-hydrodynamic (MHD) code. In conical wire arrays, the converging plasma ablated from the wires stagnates on axis, forming a standing conical shock which redirects and collimates the flow into a jet. As the jet exits the collimator shock, it is radiatively cooled and accelerated by the steep thermal gradients present. Purely hydrodynamic simulations using conditions relevant to the MAGPIE facility show good agreement with the experiments (Lebedev et al., 2002), indicating that narrow, high Mach number (M ∼ 20), radiatively cooled tungsten jets of astrophysical relevance can be obtained. To investigate the effects of lower radiative cooling on jet collimation, we modeled an aluminum conical wire array. When radiative losses are less significant, lower Mach number (M ∼ 10), less collimated jets are obtained. MHD simulations relevant to the “Z” facility were carried out to investigate the scaling of jet parameters. The resulting hypersonic (M ∼ 40), high density jets should allow the investigation of a wider range of astrophysical jet conditions.

The study of the process of evolution of the jet under outflow of water from the supercritical state through a thin nozzle

2016 ◽  
Vol 11 (1) ◽  
pp. 66-71 ◽  
Author(s):  
R.Kh. Bolotnova ◽  
V.A. Korobchinskaya
Keyword(s):  
Stationary Process ◽  
Supercritical State ◽  
System Of Differential Equations ◽  
Jet Formation ◽  
Cylindrical Coordinates ◽  
Initial Stage ◽  
Supersonic Regime ◽  
Water Outflow ◽  
Thin Nozzle ◽  
Supercritical Temperature

The dynamics of the water outflow from the initial supercritical state through a thin nozzle is studied. To describe the initial stage of non-stationary process outflow the system of differential equations of conservation of mass, momentum and energy in a two-dimensional cylindrical coordinates with axial symmetry is used. The spatial distribution of pressure and velocity of jet formation was received. It was established that a supersonic regime of outflow at supercritical temperature of 650 K is formed, which have a qualitative agreement for the velocity compared with the Bernoulli analytical solution and the experimental data.

scholarly journals Electrical Supply Circuit for a Cold Plasma Source at Atmospheric Pressure Based on a Voltage Multiplier

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2132
Author(s):  
Ovidiu S. Stoican
Keyword(s):  
Atmospheric Pressure ◽  
Cold Plasma ◽  
Plasma Source ◽  
Electrical Circuit ◽  
Jet Formation ◽  
Voltage Multiplier ◽  
Voltage Output ◽  
Intermediate Output ◽  
Electrical Supply ◽  
Lower Voltage

A cold plasma source operating at atmospheric pressure powered by a voltage multiplier is reported. In addition to its usual high voltage output, there is an intermediate output of lower voltage and higher current capability. A discharge current is drawn from both outputs. The ratio of the current supplied by each output depends on the operating state, namely, before or after the plasma jet formation. The electrical circuit is equivalent to two dc sources connected in parallel, used to initiate and sustain the electrical discharge. The plasma source is aimed to study the effect of cold plasma on the surface of various liquid or solid materials, including polymers.

LOCATING THE BLAZAR EMISSION SITE WITH FERMI VARIABILITY

2012 ◽  
Vol 08 ◽  
pp. 37-42
Author(s):  
MARKOS GEORGANOPOULOS ◽  
AMANDA DOTSON ◽  
DEMOSTHENES KAZANAS ◽  
ERIC PERLMAN
Keyword(s):  
Energy Dissipation ◽  
Broad Line ◽  
Jet Formation ◽  
Spectral Variability ◽  
Ongoing Debate ◽  
Broad Line Region ◽  
Photon Field ◽  
First Case ◽  
Line Region

This work presents a method for settling the following ongoing debate: is the GeV emission of powerful blazars produced inside the sub-pc size broad line region (BLR) or further out at scales of ~ 10 pc where the IR photon field of the dusty molecular torus dominates over that the UV field of the BLR? In the first case the GeV emission is most probably external Compton (EC) scattering of the ~ 10 eV BLR photons21, while in the second the seed photons for the EC GeV emission are the ~ 0.1 eV photons of the dust9 in the molecular torus8. The issue of the energy dissipation location is connected to the jet formation and collimation process25 and, as we argue here, can be resolved with Fermi spectral variability observations.

Peculiarities of the Power Hydrocannon Operation

2003 ◽  
Author(s):  
G. A. Atanov ◽  
A. N. Semco ◽  
O. P. Petrenko ◽  
E. S. Geskin ◽  
V. Samardzic ◽  
...  
Keyword(s):  
High Speed ◽  
Numerical Technique ◽  
Design Parameters ◽  
Jet Formation ◽  
Pressure Fields ◽  
Fluid Jets

The paper is concerned with improvement of the devices for formation of super high-speed fluid jets termed hydro cannon. Two modes of the energy injection into the fluid (the piston impact and the powder explosion) are considered and advantages of the use of the gunpowder are determined. A numerical technique for prediction of the jet formation, developed previously by one of the authors is applied for description of the velocity and pressure fields within the hydro cannon. Effect of the design parameters on the fluid acceleration is explored and suggestions for improvement of the hydro cannon design are made.

scholarly journals Jet Formation and Evolution in Baroclinic Turbulence with Simple Topography

2010 ◽  
Vol 40 (2) ◽  
pp. 257-278 ◽  
Author(s):  
Andrew F. Thompson
Keyword(s):  
Southern Ocean ◽  
Potential Vorticity ◽  
Baroclinic Instability ◽  
Length Scale ◽  
Reynolds Stresses ◽  
Mean Flow ◽  
Jet Formation ◽  
Meridional Transport ◽  
Jet Behavior ◽  
Jet Variability

Abstract Satellite altimetry and high-resolution ocean models indicate that the Southern Ocean comprises an intricate web of narrow, meandering jets that undergo spontaneous formation, merger, and splitting events, as well as rapid latitude shifts over periods of weeks to months. The role of topography in controlling jet variability is explored using over 100 simulations from a doubly periodic, forced-dissipative, two-layer quasigeostrophic model. The system is forced by a baroclinically unstable, vertically sheared mean flow in a domain that is large enough to accommodate multiple jets. The dependence of (i) meridional jet spacing, (ii) jet variability, and (iii) domain-averaged meridional transport on changes in the length scale and steepness of simple sinusoidal topographical features is analyzed. The Rhines scale, ℓβ = 2πVe/β, where Ve is an eddy velocity scale and β is the barotropic potential vorticity gradient, measures the meridional extent of eddy mixing by a single jet. The ratio ℓβ /ℓT, where ℓT is the topographic length scale, governs jet behavior. Multiple, steady jets with fixed meridional spacing are observed when ℓβ ≫ ℓT or when ℓβ ≈ ℓT. When ℓβ < ℓT, a pattern of perpetual jet formation and jet merger dominates the time evolution of the system. Zonal ridges systematically reduce the domain-averaged meridional transport, while two-dimensional, sinusoidal bumps can increase transport by an order of magnitude or more. For certain parameters, bumpy topography gives rise to periodic oscillations in the jet structure between purely zonal and topographically steered states. In these cases, transport is dominated by bursts of mixing associated with the transition between the two regimes. Topography modifies local potential vorticity (PV) gradients and mean flows; this can generate asymmetric Reynolds stresses about the jet core and can feed back on the conversion of potential energy to kinetic energy through baroclinic instability. Both processes contribute to unsteady jet behavior. It is likely that these processes play a role in the dynamic nature of Southern Ocean jets.

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