Thermal analytical model of a 30 cm mercury ion thruster

Oglebay, J. C.

doi:10.2514/6.1975-344

Cited by 3 publications

(12 citation statements)

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“…The measurement spots in [11,14] seem to be further away from the grid hole area. However, the data in [8,11] suggest a similar increase of the reported temperature data with increasing beam current. It can also be seen in Fig.…”

Section: Resultssupporting

confidence: 55%

“…An almost linear relation can be seen for our data. Figure 9 also contains grid temperature data from [8,11,14]. Oglebay [8] published analytical temperature data of the accelerator and screen grid assembly of a 30 cm Kaufman-type mercury ion thruster.…”

Section: Resultsmentioning

confidence: 99%

“…No experimental data of the temperature distribution of the grids have been published yet. Only selected analytical temperature data for the accelerator and screen grid assembly were reported in [6,8]. The lack of experimental grid temperature data is due to the fact that thermocouple measurements in the center of the grid of a firing thruster are not possible, because these measurements require mechanical and electrical contacts.…”

Section: Introductionmentioning

confidence: 99%

“…This is done by combining pyrometer line scans and precise in situ measurements of geometrical grid parameters. Thermal characterization and modeling of gridded ion thrusters has been reported by several groups: first in the 1970s for mercury ion thrusters [6][7][8], and recently for Xe ion thrusters NASA Solar Electric Propulsion Technology Application Readiness (NSTAR) [9][10][11][12] and NASA Exploration Team (NEXT) [13,14]. The temperature of various thruster parts were measured by thermocouples and modeled.…”

Section: Introductionmentioning

confidence: 99%

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In Situ Thermal Characterization of the Accelerator Grid of an Ion Thruster

Bundesmann

Tartz

Scholze

et al. 2011

Journal of Propulsion and Power

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The application of an electric propulsion diagnostic system for in situ thermal characterization of electric thrusters is studied, as described previously. Exemplarily, the surface temperature profile of the accelerator grid of a gridded ion thruster RIT-22 is obtained and characterized. In situ pyrometer line scans in combination with precise measurements of geometrical grid parameters are demonstrated. The accelerator grid surface temperature of the firing thruster is obtained by a model calculation that requires the knowledge of geometrical grid parameters, such as hole diameter, distance between holes, or grid shape. These parameters are also measured in situ with a telemicroscope for high-resolution optical imaging and a triangular laser head for surface profile scanning. The distance between grid surface and pyrometer optics are precisely monitored with the support of the triangular laser head, for which the position is fixed with respect to the pyrometer. The distance measurement allows for correcting the measurement spot size of the pyrometer. The temperature profiles at three different beam power levels (1250, 2250, and 4000 W), and warm-up and cool-down phases demonstrate the capabilities of the complex equipment. It is found that thermal steady state is reached after 4 h of thruster firing. Furthermore, it is shown that the accelerator grid surface temperature increases almost linearly with increasing beam current.

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Section: Resultssupporting

confidence: 55%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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In Situ Thermal Characterization of the Accelerator Grid of an Ion Thruster

Bundesmann

Tartz

Scholze

et al. 2011

Journal of Propulsion and Power

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“…Thermal vacuum testing and modeling has occurred on several previous generations of ion thrusters including 20-cm mercury ion thrusters, 1 30-cm mercury ion thrusters (including the J-series thruster), [2][3][4][5] and 30-cm xenon ion thrusters (including the NSTAR/DS-1 thruster).…”

Section: Introductionmentioning

confidence: 99%

NEXT Ion Thruster Thermal Model

Noord¹

2007

43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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As the NEXT ion thruster progresses towards higher technology readiness, it is necessary to develop the tools that will support its implementation into flight programs. An ion thruster thermal model has been developed for the latest prototype model design to aid in predicting thruster temperatures for various missions. This model is comprised of two parts. The first part predicts the heating from the discharge plasma for various throttling points based on a discharge chamber plasma model. This model shows, as expected, that the internal heating is strongly correlated with the discharge power. Typically, the internal plasma heating increases with beam current and decreases slightly with beam voltage. The second is a model based on a finite difference thermal code used to predict the thruster temperatures. Both parts of the model will be described in this paper. This model has been correlated with a thermal development test on the NEXT Prototype Model 1 thruster with most predicted component temperatures within 5-10 °C of test temperatures. The model indicates that heating, and hence current collection, is not based purely on the footprint of the magnet rings, but follows a 0.1:1:2:1 ratio for the cathode-to-conical-to-cylindrical-tofront magnet rings. This thermal model has also been used to predict the temperatures during the worst case mission profile that is anticipated for the thruster. The model predicts ample thermal margin for all of its components except the external cable harness under the hottest anticipated mission scenario. The external cable harness will be re-rated or replaced to meet the predicted environment. AIAA 2007-5218This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States.

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Numerical Thermal Model of NASA Solar Electric Propulsion Technology Application Readiness Ion Thruster

Noord

Gallimore

Rawlin

2000

Journal of Propulsion and Power

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A thermal computer model of the 30-cm NASA solar electric propulsion technology application readiness (NSTAR) xenon ion thruster has been produced using a lumped-parameter thermal nodal-network scheme. This model contains 104 nodes on the thruster and was implemented using SINDA and TRASYS on various UNIX workstations. The model includes the radiation and conduction heat transfer, the effect of plasma interaction on the thruster, and an account for nely perforated surfaces. The model was developed in conjunction with an NSTAR thruster out tted with approximately 20 thermocouples for thermal testing at the John H. Glenn Research Center. The results of these experiments were used to calibrate and con rm the computer model rst without and then with the plasma interaction. The calibrated model was able to predict discharge chamber temperatures to within 10 ± C of measured temperatures. To demonstrate the ability of the model under various circumstances, the heat ux was examined for a thruster operating in a deep-space environment. NomenclatureA I = area of I th element, m 2 A J = area of J th element, m 2 C i = thermal capacitance at node i , cal/g¢ K F i j = form (view) factor G j i = linear conductor attaching node j to node i , W/K H j i = radiation conductor attaching node j to node i , W/K 4 J A = ion current hitting grid, A J B = ion beam current, A N = number of nodes Q i = heat source or sink for node i , W r i j = distance between the i th and j th element, m T k + 1 i = temperature of node i for the k + 1 iteration, K T n + 1 i = temperature of node i at time t + D t , K T k j = temperature of node j for the kth iteration, K T n j = temperature of node j at time t, K U + = ionization energy, eV V P = discharge chamber plasma potential with respect to ambient space plasma potential, V h i = angle between normal of i th element and the line connecting the i th and j th element, rad h j = angle between normal of j th element and the line connecting the i th and j th element, rad U N = neutralizer power, W U sh = self-heating power deposited in the discharge chamber in the form of heat, W U T = total thruster power, W

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Thermal analytical model of a 30 cm mercury ion thruster

Cited by 3 publications

References 0 publications

In Situ Thermal Characterization of the Accelerator Grid of an Ion Thruster

In Situ Thermal Characterization of the Accelerator Grid of an Ion Thruster

NEXT Ion Thruster Thermal Model

Numerical Thermal Model of NASA Solar Electric Propulsion Technology Application Readiness Ion Thruster

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