Capillary discharge in the electrothermal gun

Powell, J. David; Zielinski, A.E.

doi:10.1109/20.195642

Cited by 69 publications

(55 citation statements)

References 12 publications

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“…4,5,6 Some initial theoretical models aimed to analyze existing experimental data and build a phenomenological description of the ablation processes. Later, more sophisticated steady state 7,8 and unsteady theoretical models 9,10,11 were proposed to describe capillary discharges for an electrothermal gun.…”

Section: Introductionmentioning

confidence: 99%

Ablation Study in a Capillary Sustained Discharge

et al. 2007

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Abstract-Electrothermal-chemical (ETC) ignitionsystems have been demonstrated in gun systems to provide desirable characteristics including reproducible shorter ignition delays. The optimum combination of capillary tube and fuse wire properties has not been identified yet. We present a combined theoretical and experimental study of the capillary discharge with an aim to develop a capillary plasma source with efficient energy conversion. The major emphasis in the present capillary discharge model is the ablation phenomenon. Consideration is given to different characteristic subregions near the ablated surface: namely, a space-charge sheath, a Knudsen layer, and a hydrodynamic layer. A kinetic approach is used to determine the parameters at the interface between the kinetic Knudsen layer and the hydrodynamic layer. Coupling the solution of the nonequilibrium Knudsen layer with the hydrodynamic layer provides a self-consistent solution for the ablation rate. According to the model predictions, the peak electron temperature is about 1.4 eV, the polyethylene surface temperature is about 700 K, and the pressure is about 10 MPa in the case of a 0.6 kJ discharge. In parallel, a parametric experimental study of the capillary ablation process is conducted. The ablation rates are measured for capillary tubes made of polyethylene and Teflon. Both experimental measurements and simulations indicate that the ablated mass increases with the peak discharge current and that a smaller diameter capillary yields a larger ablated mass. It is found that model predictions agree well with experimental measurements. Report Documentation PageForm Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.

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Section: Introductionmentioning

confidence: 99%

Ablation Study in a Capillary Sustained Discharge

et al. 2007

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“…Similar approaches have been used to determine the mass ablation from the bore wall in several one-dimensional modeling efforts such as in the numerical studies by Powell and Zielinski 18) and Kim. 11) In the above equation, the factor f represents the deviation of radiative flux from the blackbody behavior.…”

Section: )mentioning

confidence: 99%

Transient Shock Formation of Pulsed Electrothermal Plasma Discharge Confined in an Extended Bore

Kim

Kwak

Park

2010

JTST

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An electrothermal gun possesses a great potential to be an efficient source of pulsed plasma discharge for nanomaterials production or thermal plasma spray coatings. A plasma discharge by intense pulsed power is numerically studied utilizing time-dependent gas dynamics equations which are solved by FCT (flux-corrected transport) algorithm in two-dimensional domain of the interior capillary bore region and the external region of extended bore. Plasma conditions at the bore exit, mass ablation of polycarbonate bore wall, and degree of ionization are determined at different levels of transient arc current profile. As a way to controlling the plasma discharge, the extended bore at the capillary exit is considered and the flow pattern of pulsed plasma discharge in the extended bore exhibit complex shock structure from slightly to highly underexpanded jet depending on the level of arc current profiles. Flow instability of oscillating Mach disk is found at higher level of arc current profile cases.

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“…Other possible reasons for these minor differences could be different setting of grid points or time steps, different scheme used for the simulation, and so forth. For more detailed information about the simulation and the discussion about the simulated plasma flow properties, one can found them in [4,11,21]. Based on the above simulation, the efficiency of present methods is studied.…”

Section: The Second Test Is For Procedures (A)-(d)mentioning

confidence: 99%

“…where in and in represent the SIE and density determined by (19)- (21). These two could be viewed as inputting data for solving (24).…”

Section: Solving the Saha Equation In The Simulation Of Capillary Dismentioning

confidence: 99%

“…Equations (19)- (23) are the time-dependent 1D mathematical model used to simulate capillary discharge for the ET or ETC launch technology [4,11,21]. In this set of models, stands for time and stands for axial coordinate, is the mass density, is the velocity of the plasma flow, is the ablation rate which causes the increasing of , is the pressure, is the specific internal energy (SIE), is the conductivity, and 2 / is the inputting energy in the form of joule heating.…”

Section: Solving the Saha Equation In The Simulation Of Capillary Dismentioning

confidence: 99%

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A Study on the Efficient Method for the Solution of the Saha Equation in the Numerical Simulation of Capillary Discharge

Liu

Wan

et al. 2017

Advances in Mathematical Physics

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In the numerical simulation of capillary discharge for the Electrothermal (ET) or ET-chemical (ETC) launch system, one needs to solve the Saha equation to determine the composition of plasma for the transport coefficients. This would cause a relatively longer simulation runtime compared with conventional computational fluid dynamics problems. In this paper, the relatively difficult multidimensional problem of solving the Saha equation is transformed into a one-dimensional problem in the simulation of capillary discharge by constructing an iteration equation about temperature. A coefficient is introduced to ensure the convergence of this iteration equation. In order to improve the computational efficiency, this coefficient is further optimized and the methods of setting the iteration initial value dynamically are introduced. Several simulation tests are conducted to study the performance of these two methods. The results show that the simulation runtime could be significantly reduced with the methods presented in this paper.

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Capillary discharge in the electrothermal gun

Cited by 69 publications

References 12 publications

Ablation Study in a Capillary Sustained Discharge

Ablation Study in a Capillary Sustained Discharge

Transient Shock Formation of Pulsed Electrothermal Plasma Discharge Confined in an Extended Bore

A Study on the Efficient Method for the Solution of the Saha Equation in the Numerical Simulation of Capillary Discharge

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