Numerical and Experimental Study on Discharge Characteristics of High-Current Hollow Cathode

Kubota, Kei; Oshio, Yuya; Watanabe, Hiroki; Cho, Shinatora; Ohkawa, Yasushi; Funaki, Ikkoh

doi:10.2514/6.2016-4628

Cited by 13 publications

(12 citation statements)

References 11 publications

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“…The discharge voltage varies between 16 and 31 V for HC60, between 15 and 30 V for HC20. The general trends presented here are consistent with the behavior of cathodes of this power range found in the literature [16,42,43].…”

Section: Hollow Cathodes Performancesupporting

confidence: 91%

Triple Langmuir Probes Measurements of LaB6 Hollow Cathodes Plume

et al. 2019

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Lanthanum hexaboride hollow cathodes represent a viable option for high power Hall effect thruster applications, under development for the next generation of manned and robotic interplanetary missions. In this scenario, SITAEL and the University of Pisa are actively developing high current hollow cathodes capable of providing discharge current in the range 10-100 A to be coupled with high power Hall effect thrusters. The cathode design is based on an in-house theoretical model of the internal sections of the cathode, recently integrated with a simplified model of the cathode plume. Despite the application of hollow cathodes on flight and laboratory model Hall effect thrusters, many questions remain unsolved. In particular, issues related to onset of instabilities, due to plume mode or ion acoustic turbulence, are still unclear, while it is known that they can affect the overall performance of the cathode and thruster unit. This paper focuses on the experimental investigation of the cathode plume by means of measurements of the main plasma parameters, at different operating conditions and for different cathode geometry. Two cathodes were investigated, namely HC20 and HC60, designed to be coupled with SITAEL's HT5k and HT20k (5 kW-and 20 kW-class) Hall effect thrusters. The cathodes were mounted in stand-alone configuration with an auxiliary cylindrical anode. The experimental campaign was performed using triple Langmuir probes as plasma diagnostic system. The probes were mounted on scanning mechanisms to measure the plume parameters at various radial and axial distances from the keeper exit. General trends of electron temperature, plasma potential and plasma density are reported in terms of discharge current, mass flow rate and cathode orifice geometry. The results highlight that the cathode plate orifice selection affects the plume mode onset, giving the possibility to extend the stable mode of cathode operation in the current range required by the thruster.

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Section: Hollow Cathodes Performancesupporting

confidence: 91%

Triple Langmuir Probes Measurements of LaB6 Hollow Cathodes Plume

et al. 2019

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“…The cathode and a ring-shaped anode were configured with a gap of 37 mm. 27) The discharge voltage was set as the electric potential on the downstream boundary. To keep the discharge current constant, the maximum emitter temperature T em;max was periodically adjusted.…”

Section: Boundary Conditionsmentioning

confidence: 99%

Hybrid-PIC Simulation of LaB<sub>6</sub> Hollow Cathode Self-Heating Characteristics

Kubota

Oshio

Watanabe

et al. 2019

Trans. Japan Soc. Aero. S Sci.

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Numerical simulation of plasma flow and the self-heating characteristics of a LaB 6 hollow cathode were performed using a hybrid-PIC model. For a discharge current of 30 A and mass flow rate of 3 mg/s, the influences of an emitter temperature profile and model parameter included in an anomalous resistivity model on the plasma flow and energy flux were investigated. In the simulation, the discharge voltage was fixed at a predetermined value and the maximum emitter temperature was periodically adjusted to keep the discharge current constant. The results show that the present model predicts the keeper floating voltage within an accuracy of 20%. It is found that the main reason for the emitter temperature to rise is due to ion bombardment and accompanying recombination energy, and that the maximum emitter temperature can be kept lower as the emitter temperature profile becomes uniform. It is also shown that thermal input into the emitter is decreased when anomalous resistivity increases.

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“…Our goal in researching hollow cathodes is to establish a stress-free hollow-cathode heater that enables high durability and reliability. In previous studies, [16][17][18][19] we proposed a hollow cathode with a non-contact radiative heater ( Fig. 2(a)).…”

Section: Introductionmentioning

confidence: 99%

“…Following successful demonstration of the radiative-heater hollow cathode, 18,19) the objective of the present paper is to optimize the hollow-cathode performance for 5-10-kW Hall thrusters. For this purpose, we study the effect of orifice and keeper geometries on the performance of a high-current hollow cathode with a radiative heater.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of LaB<sub>6</sub> Hollow Cathode with Radiative Heater

Oshio

Kubota

Watanabe

et al. 2019

AEROSPACE TECHNOLOGY JAPAN

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A lanthanum hexaboride (LaB6) hollow cathode with radiative heater has been developed for high power Hall thruster neutralizer. The influences of orifice and keeper shapes on the performance of the hollow cathode and on its operating characteristics are investigated by measuring the discharge voltage and current. Six different orifice shapes are used in this study: straight, long tapered, and short tapered, each with an orifice diameter of 2 or 3 mm. The straight orifice with the 2-mm diameter has the widest range of spot-mode operation, although no effect of orifice shape is observed for the 3-mm diameter. This is because the high neutral-gas density around the orifice fosters transition to the spot mode from the plume mode with a straight φ2-mm orifice. Regarding the effect of the keeper, having a large exit diameter and the shortest distance possible between the cathode tube and the keeper gives the widest range of spot-mode operation.

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Numerical and Experimental Study on Discharge Characteristics of High-Current Hollow Cathode

Cited by 13 publications

References 11 publications

Triple Langmuir Probes Measurements of LaB6 Hollow Cathodes Plume

Triple Langmuir Probes Measurements of LaB6 Hollow Cathodes Plume

Hybrid-PIC Simulation of LaB<sub>6</sub> Hollow Cathode Self-Heating Characteristics

Experimental Investigation of LaB<sub>6</sub> Hollow Cathode with Radiative Heater

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