Ion Heating Measurements on the Centerline of a High-Current Hollow Cathode Plume

Dodson, Christopher A.; Perez-Grande, Daniel; Jorns, Benjamin; Goebel, Dan M.; Wirz, Richard E.

doi:10.2514/1.b36788

Cited by 18 publications

(16 citation statements)

References 27 publications

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“…Spot mode indicates the stable mode of operation desired during the nominal coupling with the thruster, whereas plume mode indicates an unstable mode, characterized by the presence of large-amplitude oscillations in the discharge and keeper voltages, which promote the keeper wear [7,[21][22][23]. As mentioned above, another phenomenon thought to enhance the keeper wear even when the cathode is in spot mode is the production of high-energy ions, the existence of which was confirmed by direct measurements [18,19]. The transition between spot and plume mode in general arises when the ratio of discharge current to mass flow rate exceeds a value dependent on various parameters, including the cathode geometry.…”

Section: Introductionmentioning

confidence: 93%

“…Several different mechanisms have been proposed to identify the source of these energetic ions, including potential hills [11], charge exchange between ions and neutrals [12], double and triple ionization [13,14], energetic ion production by plasma oscillations largely associated with ionization instabilities [15,16], and/or by ion acoustic turbulence [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

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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: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Triple Langmuir Probes Measurements of LaB6 Hollow Cathodes Plume

et al. 2019

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“…Researchers had measured the ion energy distribution function in the hollow cathode plume [154] using a RPA and studies had shown that the energy far exceeds the discharge voltage (usually 15-20 V). This attracted attention on nonclassical ion transport, namely ion acoustic turbulence driven heating of ions [155][156][157], with direct measurement of IVDFs in the plume enabled via LIF and RFEAs [158][159][160]. An example of LIF setup in the hollow cathode assembly is presented in figure 16 [160].…”

Section: Hall-effect Thrustersmentioning

confidence: 99%

Laser induced fluorescence diagnostic for velocity distribution functions: applications, physics, methods and developments

Yip

Jiang

2021

Plasma Sci. Technol.

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With more than 30 years of development, laser-induced fluorescence (LIF) is becoming an increasingly common diagnostic to measure ion and neutral velocity distribution functions in different fields of studies in plasma science including Hall thrusters, linear devices, plasma processing, and basic plasma physical processes. In this paper, technical methods used in the LIF diagnostic, including modulation, collection optics, and wavelength calibration techniques are reviewed in detail. A few basic physical processes along with applications and future development associated with the LIF diagnostics are also reviewed.

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“…The correlation between ion acoustic turbulence (IAT) wave energy and ion energy was discussed by Dodson et al 19) The transfer of electron kinetic energy to ion kinetic energy through wave energy can be caused by the electrostatic instability in IAT. The existence of IAT and its contribution to ion heating were examined by Jorns et al and Dodson et al 19,20) The wave in IAT is the fluctuation of potential created by the difference in the velocities of electrons and ions. When the drift velocity of electrons is higher than the ion acoustic velocity, the ions cannot follow the electrons and are left behind.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Discharge Mode on Ion Energy and Plasma Potential in the Plume Plasma Region

Imai

Imaguchi

Watanabe

et al. 2022

Trans. Japan Soc. Aero. S Sci.

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The ion energy angle distribution and its relationship to plasma parameters for spot and plume modes are elucidated for a LaB 6 hollow cathode with a radiative heater. Measurements were conducted using a retarding potential analyzer (RPA) and a single Langmuir probe. The ion energy distribution function (IEDF) characteristics showed different tendencies in the current density and mass flow-rate dependence under different plasma modes. The IEDF peak potential for the spot mode varied from 16 to 23 V with increasing current density, and the IEDF peak potential for the plume mode varied from 16 to 32 V with decreasing mass flow rate. Considering angle dependency of ion energy, when the observation angle was changed from the radial direction to the axial direction, the IEDF peak potential increased from 29 to 40 V for the plume mode (10 A, 10 sccm) and increased slightly from 16 to 18 V for the spot mode (20 A, 30 sccm). The probe measurement analysis revealed that the IEDF peak energies are the same as, or exceed, the plasma potential and have a qualitative correlation with the electron temperature spatial distribution.

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Ion Heating Measurements on the Centerline of a High-Current Hollow Cathode Plume

Cited by 18 publications

References 27 publications

Triple Langmuir Probes Measurements of LaB6 Hollow Cathodes Plume

Triple Langmuir Probes Measurements of LaB6 Hollow Cathodes Plume

Laser induced fluorescence diagnostic for velocity distribution functions: applications, physics, methods and developments

The Effect of Discharge Mode on Ion Energy and Plasma Potential in the Plume Plasma Region

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