Ion Engine Grid Gap Measurements

Soulas, George C.; Frandina, Michael M.

doi:10.2514/6.2004-3961

Cited by 10 publications

(14 citation statements)

References 9 publications

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“…The grid curvature decreases or increases abruptly upon switching the beam voltage on or off, respectively, and subsequently relaxes. The abrupt change can be attributed to electrostatic forces between the screen and accelerator grid, which slightly increase the grid spacing [16]. With increasing firing time, the whole thruster expands due to rising temperature, which leads to relaxation of the grid curvature.…”

Section: Resultsmentioning

confidence: 98%

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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: Resultsmentioning

confidence: 98%

“…Unfortunately, the grid gap cannot be determined from our experimental data. To measure the grid gap, modifications of the grids and the experimental setup are needed [16]. However, the grid curvature change is very small.…”

Section: Resultsmentioning

confidence: 99%

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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“…By comparing the experimental results with NASA experiments on grid thermal deformation [10,13,14], it is found that grid thermal deformation has the following characteristics:…”

Section: Grids Deformation Characteristicsmentioning

confidence: 99%

“…Trava-Airoldi's optical measurement method was very demanding on the lens and sensitive to environmental vibration. Based on the improvement of the above problems, Soulas [13] measured the thermal deformation of the grid using a telemicroscope and bolted probes. This measurement method could operate under the condition of the ion thruster with the plasma beam, and the grids' thermal deformation and hot gap of the NASA Solar Electric Propulsion Technology Readiness (NSTAR) thruster 30 cm titanium ion optics were measured successfully.…”

Section: Introductionmentioning

confidence: 99%

Grid Deformation Real-Time Measurement System of Ion Thruster Based on Videometrics

et al. 2019

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In order to conduct high-precision measurement of the LIPS-300 ion thruster grid deformation in a vacuum, high-temperature, and plasma environment, a noncontact videometrics system using a telemicroscope was designed. Based on the captured image, the interactive partitioning edge detection method (IPEDM) was used to obtain stable and clear edges of multiple circular cooperative targets. Meanwhile, magnification factor calibration, rotation angle correction, and subpixel-level grid deformation measurement were performed with cooperative targets. The measurement results show that under the power of 750 W in the discharge chamber, the maximum thermal deformation of the screen grid is 1120 μm, and the gap between the screen grid and the accelerator grid is reduced by 420 μm. An accuracy assessment of the system shows that the grid deformation measurement accuracy is better than 12 μm, and the system satisfies the requirement of high-precision real-time measurements of the grid thermal deformation of the ion thruster under the discharge-chamber-running condition and the plasma-beam-extraction condition.

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“…Figure 3 shows the predicted wall erosion rates from that reference versus the fraction of maximum perveance determined using the measured hot grid gaps (Ref. 23). The operation at NSTAR's lowest power throttling point has a lower wear rate predicted than what would be expected based purely on its fraction of maximum perveance.…”

Section: Accelerator Gridmentioning

confidence: 99%