Consistent treatment of critical plasma flows in high pressure discharge ablative capillaries

Cuperman, S.; Zoler, D.; Ashkenazy, J.; Caner, Mehmet; Kaplan, Z.

doi:10.1109/27.277553

Cited by 23 publications

(15 citation statements)

References 5 publications

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“…For the case where the capillary radius is set to 2.5 mm, the percent difference decreases from 52% to 31%. These results are consistent with the work of Cuperman et al on plasma flows in high pressure discharge ablative capillaries [8], and Weiss et al on the extension of the capillary by an extension pipe [9].…”

Section: Resultssupporting

confidence: 93%

Optimization of capillary source geometry for maximum pellet exit velocity in electrothermal plasma launchers

Esmond

Winfrey

2013

2013 IEEE 25th Symposium on Fusion Engineering (SOFE)

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Deep fueling for large-scale tokamak fusion reactors requires the use of high-velocity pellet injectors. The fuel pellets consist of frozen deuterium or deuterium-tritium ice. A fuel pellet must be launched into the fusion plasma at a high enough velocity to reach the core of the plasma before too much of the pellet melts, ablates and disintegrates. For tokamak fusion reactors, the fusion plasma is predicted to operate at temperatures of up to 15x10 7 °C at its core. At these extreme temperatures, the fuel pellets need to be launched at large velocities to prevent excessive melting and vaporization before reaching the core of the plasma. Obtaining this exit velocity is possible through the use of electrothermal (ET) plasma guns. Electrothermal plasma guns use a capillary tube where plasma is sparked inside the source and is allowed to continue travelling in an extension acceleration barrel. The plasma is sparked inside the source via the discharge of a capacitor bank that is charged up to 10 kV or higher. A liner material inside the source is ablated and forms plasma that draws discharge current (several kA) over 100 microseconds and can propel a pellet to velocities exceeding 3 km/s. Using a 1-D time-dependent computer code, a variety of computational predictions can be made on the plasma, as well as the pellet, as it moves through the barrel until it leaves towards the fusion core. Characteristics of different geometric configurations of the plasma gun can be simulated using the code to predict the optimal geometric configuration that will maximize the pellet's exit velocity. Previous research studies have been conducted by varying the length of the acceleration barrel and computing the effect on the pellet's exit velocity. In the present research, to complement the prior studies, the one dimensional computer code, ETFLOW, was used to simulate the effect of varying the source geometry, i.e. length, radius, and aspect ratio, on the pellet's exit velocity. For optimal geometries, pellet exit velocities of up to 3.9 km/s were computed. This is an increase of nearly 12% from previous computational studies. Computed pellet velocities are correlated to source geometry and plasma parameters.

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Section: Resultssupporting

confidence: 93%

Optimization of capillary source geometry for maximum pellet exit velocity in electrothermal plasma launchers

Esmond

Winfrey

2013

2013 IEEE 25th Symposium on Fusion Engineering (SOFE)

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“…As the power is practically the same in both experiments, we may expect [4] that the plasma jet characteristics (density, temperature and velocity) to be similar. Therefore, we assume the specific mass loss to be similar in both experiments.…”

Section: Dependence Of the Capillary And Anode Mass Losses On Thmentioning

confidence: 86%

“…7(a) and (b) and Table VI. A general remark that can be drawn is that lower power (longer pulse durations) leads to larger total and specific capillary mass losses. Taking into consideration the models predictions [4], lower powers means colder plasma jets.…”

Section: Dependence Of the Capillary And Anode Mass Losses On Thmentioning

confidence: 99%

Reliable, highly reproducible plasma injectors for electrothermal and electrothermal-chemical launchers

et al. 2005

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The plasma injector is a major component within electrothermal (ET) or electrothermal-chemical (ETC) launcher. Soreq NRC has promoted for years the solid-propellant ETC (SPETC) gun concept, where the generated plasma jet serves to ignite the charge and to control its burning rate (for example, to eliminate the effect of the initial charge temperature on the propellant burning rate). From a system engineering point of view, there is an advantage in using small size plasma injectors. Such injectors have been designed, built, and tested in our laboratory in the past few years. In this paper, we report about "free jet" (the plasma is injected to the atmosphere and not into propellant charge) experiments performed with certain models of such injectors. These injectors were designed for electrical energies in the range of hundreds of kilojoules and several hundred megawatts. The dependence of the mass losses from the ablative capillary and anode on the total electrical energy and power are presented. Although the limited scope of this presentation one can grasp from these data indications regarding the differences between the thermodynamic properties (temperature, density) of plasma jets produced by capillaries with different geometries, operated at various electrical energies and powers. A comparison between the energy carried by the plasma and metal droplets (resulting from anode melting) may give an indication about the relative contribution of these two factors to the propellant ignition.

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“…Then the capillary behaviour can be characterized in terms of just three parameters: its radius a and length I and the current /. In principle, these parameters can be varied in order to change the plasma parameters (Zoler et al 1993a,b;Cuperman et al 1993), such as density, velocity, temperature and pressure, for specific purposes. Nevertheless, because of the interdependence of the various parameters describing the capillary behaviour, the design of a capillary for a specific application may face difficulties.…”

Section: Introductionmentioning

confidence: 99%

Analysis of plasma critical flow in ablative discharge capillaries with a non-constant cross-section

Ashkenazy¹,

Zoler

1995

J. Plasma Phys.

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A quasi-one-dimensional model for the steady-state flow of a plasma in an ablative discharge capillary is presented for capillaries with non-constant cross- section. It is demonstrated that small modifications of the capillary geometry can lead to significant changes in the plasma exit parameters. In this respect, the possibility of obtaining an extended range of plasma parameters makes this type of ablative capillary a useful source of plasma for a variety of applications. Numerical solution of the equations of the model for the critical-flow case allows evaluation of the main fluid-dynamic and thermodynamic parameters of the plasma inside the capillary and at its exit.

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Consistent treatment of critical plasma flows in high pressure discharge ablative capillaries

Cited by 23 publications

References 5 publications

Optimization of capillary source geometry for maximum pellet exit velocity in electrothermal plasma launchers

Optimization of capillary source geometry for maximum pellet exit velocity in electrothermal plasma launchers

Reliable, highly reproducible plasma injectors for electrothermal and electrothermal-chemical launchers

Analysis of plasma critical flow in ablative discharge capillaries with a non-constant cross-section

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