Arc heater development at AEDC

Arc heaters are important items of equipment for ground thermal appraisal of space probes returning to Earth. However, cathodes of arc heaters are seriously ablated, which limits the appraisal. Micro multi-electrode technology is characterized by multiple spots, which has the potential to reduce cathode ablation. In order to develop this technology, Cu-LaB 6 alloys were prepared by using a hot press sintering furnace with a LaB 6 content of mol. 0.03%-1% and average particle size of 18-60 µm. The influence of current, discharge distance, LaB 6 content, LaB 6 size and magnetic field on the arc spot mode was studied. The similarity parameter of the arc spot mode was analyzed. The arc spot has three modes: single-spot mode (SSM), multi-spot mode (MSM) and branched-spot mode (BSM). With the increase in the discharge current, the arc spot changes in the order of the BSM, the MSM and the SSM. With the increase in the discharge distance, the arc spot changes in the opposite order. Increasing the content or decreasing the size of LaB 6 can make the MSM region move in the direction of decreasing current and increasing discharge distance. A model for arc spot transition is proposed. The change of the arc spot from the MSM to the BSM is related to the arc constriction.

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Impacts of external magnetic fields applied to high-pressure electric arc heaters

Horn

Felderman

MacDermott

1996

Journal of Propulsion and Power

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Acceptable behavior of electrical arc discharges inside high-power arc heaters usually requires the introduction of externally applied magnetic fields near the arc terminations. The strength and spatial distribution of these fields are discussed for a typical configuration. The effects of the Lorentz force produced by these fields on the arc discharge near the electrodes are evaluated in terms of azimuthal, axial, and radial components of the force. In general, there are only two possible states of the Lorentz force interaction with the arc, one of which enhances the gas swirl and the arc attachment, the other opposes the gas swirl and the arc attachment. Simple rules are given for ensuring the proper polarity of the magnetic field to obtain the desired result. An analysis of the proper scaling of the magnetic field strength in conjunction with geometric scaling of the arc heater shows that the magnetic field strength is only weakly dependent on scale. Nomenclature B = magnetic field strength, G D = diameter, cm D* = throat diameter, cm F = force, N H = enthalpy, MJ/kg 7 = current, A i = unit vector J = current density, A/cm 2 L = characteristic length, cm P -pressure, MPa r = radial coordinate, radius, cm s = general length coordinate, cm t -time, s z = axial coordinate, cm j3 = scaling factor 0 = azimuthal coordinate, rad fju = gas viscosity, kg/m/s p = gas density, kg/m 3 cr = electrical conductivity, mho/m v = gas velocity, cm/s Subscripts a -arc B = bulk or mass average b = bore L = Lorentz r = radial component z = axial component 0 = reservoir or stagnation value 6 = azimuthal component

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Arc heater development at AEDC

Cited by 5 publications

References 8 publications

Review of DC and AC Arc Plasma at High Pressures Above Atmospheric Pressure

Review of DC and AC Arc Plasma at High Pressures Above Atmospheric Pressure

Arc spot formation conditions and influencing factors of a micro multi-electrode technology

Impacts of external magnetic fields applied to high-pressure electric arc heaters

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