Development of an Iodine Compatible Hollow Cathode

Thompson, Seth J.; VanGermert, Jack J.; Farnell, Casey C.; Farnell, Cody C.; Farnell, Shawn; Hensen, Tucker J.; Ham, Ryan; Williams, Desiree D.; Chandler, James M.; Williams, John D.

doi:10.2514/6.2019-3997

Cited by 5 publications

(4 citation statements)

References 6 publications

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“…Eq. 7 Gaussian smoothing function 𝐺 = exp(( 𝐸 − 𝐵 𝑖 𝜌 ) 2 (7) where 𝜌 = 1.5𝑒𝑉 is the variance used for all calculations presented in this work, and E and Bi are defined in Eq. 3 and 4, respectively.…”

Section: Appendix a (Tables And Figures)mentioning

confidence: 99%

“…In recent years the use of storable atomic propellants like bismuth and mercury for high thrust applications, and zinc and magnesium for high specific impulse applications has been investigated [1][2][3][4]. Some molecular propellants have been investigated, such as water (where the thruster operates on hydrogen and oxygen gas created by electrolysis) [5,6], iodine [7][8][9][10][11][12][13], and adamantane [14][15][16], but were all found to have prohibitive disadvantages such as significantly lower performance compared to xenon. A paper on the first in-space demonstration of (low-power) thruster operation on iodine vapor was recently published in Nature [13].…”

Section: Introductionmentioning

confidence: 99%

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Aromatic Hydrocarbons as Molecular Propellants for Electric Propulsion Thrusters

Borrfors

Harding

Weissenreider

et al. 2023

Preprint

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The aromatic hydrocarbons (AHs) fluorobenzene, naphthalene, and 1fluoronaphthalene are introduced as promising alternatives to xenon as propellant for in-space electric propulsion (EP). These storable molecules have similar mass, lower cost, and lower ionization energies compared to xenon, as well as the critical advantage of low post-ionization fragmentation compared to other molecular propellant candidates. The ionization characteristics of AHs are compared with those of xenon and the diamondoid adamantane, previously evaluated as a molecular propellant for EP. Quantum chemical calculations and BEB theory together with 25 eV electron ionization mass spectrometry (EI-MS) measurements have been used to predict the fragmentation of the AHs and adamantane when ionized in a plasma with an electron temperature of 7 eV (a typical electron temperature in EP plasmas). A high fraction (81 − 8 %) of the detected AH ions originate from intact molecules, compared to 3 % for adamantane. indicating extraordinarily low fragmentation for the selected AHs. The ionization potential of the AHs is similar to that of adamantane but lower compared to xenon (8.14–9.2 eV for the AHs, 9.25 for adamantane and 12.13 eV for xenon). BEB calculations have also been used to predict total ionization cross sections. The calculated ionization cross section of the AHs is comparable to that of adamantane but 3–5 times higher than that of xenon, which together with the low ionization potential can contribute to more efficient ionization. The AHs may have the potential to perform better than xenon, despite the absence of fragmentation in xenon.

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Section: Appendix a (Tables And Figures)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Aromatic Hydrocarbons as Molecular Propellants for Electric Propulsion Thrusters

Borrfors

Harding

Weissenreider

et al. 2023

Preprint

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“…In 2019, Thompson developed a graphite hollow cathode with a precursor cermet emitter. After 72 h of operation on iodine, the results showed that carbon is compatible with iodine because no signs of corrosion or degradation were detected inside the graphite cathode tube [11].…”

Section: Introductionmentioning

confidence: 98%

Early experimental investigation of the C12A7 hollow cathode fed on iodine

Hua

Wang

Ning

et al. 2022

Plasma Sci. Technol.

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To fully realize the superiority of the iodine electric propulsion system in streamlining the size and reducing the operating cost, iodine hollow cathode technology must be developed. Considering the corrosiveness of iodine and the possible impurity of working propellant, the C12A7 hollow cathode with promising chemical ability was developed and tested. The C12A7 hollow cathode with a nominal current of 1-4 A was successfully ignited with iodine from the reservoir outside the vacuum chamber. It was operated at 1 A of anode current with a 1.2 mg/s iodine mass flow rate. Despite involuntary extinguishment, the C12A7 hollow cathode could be restarted repeatedly with a single operation time of up to twelve minutes and a total duration of half an hour. The unexpected fluctuation of iodine flow may be the reason for the short operation time. Experimental results and microscopical observation of the electride emitter show the compatibility of the iodine and electride emitter. For the development and demonstration of future single iodine electric propulsion of Hall thrusters, the iodine storage and supply system with precise control and regulation may be the critical technology.

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“…However, iodine systems have other issues owing to their corrosiveness. For example, cathode corrosion is directly related to shorter lifetime [17,18]. In addition, all components of a spacecraft should be compatible with iodine, and specific test facilities should be used for the safe exhaust of iodine vapor [17,19,20], both of which increase the cost and time for development.…”

Section: Introductionmentioning

confidence: 99%

Demonstration and experimental characteristics of a water-vapor Hall thruster

et al. 2023

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Water is an attractive candidate for condensable propellants owing to its availability, handleability, and sustainability. This study proposes the use of water vapor as a propellant for a low-power Hall thruster, and experimentally demonstrates the feasibility of this proposal. Based on the performance estimation from the plume diagnostics, a thrust-to-power ratio of 19 mN/kW, specific impulse of 550–860 s, and anode efficiency of 5–8 % were obtained at an anode power of 233–358 W. From further efficiency analysis, the mass utilization efficiency of water was found to be the most deteriorated among the internal efficiencies compared to the conventional xenon propellant, which was consistent with the expectations from a small discharge current oscillation, large beam divergence, and increase in low-energy ions. Moreover, additional power loss via reactions unique to polyatomic molecules was indicated by evaluation of the ionization cost. In this experiment, the mass utilization efficiency was improved with an increase in the anode voltage from 200 to 240 V without degradation of the power utilization. This suggests that operating at a higher voltage is more suitable for a water-vapor Hall thruster.

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Development of an Iodine Compatible Hollow Cathode

Cited by 5 publications

References 6 publications

Aromatic Hydrocarbons as Molecular Propellants for Electric Propulsion Thrusters

Aromatic Hydrocarbons as Molecular Propellants for Electric Propulsion Thrusters

Early experimental investigation of the C12A7 hollow cathode fed on iodine

Demonstration and experimental characteristics of a water-vapor Hall thruster

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