Spatially-Resolved Beam Current and Charge-State Distributions for the NEXT Ion Engine

Pollard, James E.; Diamant, Kevin D.; Crofton, Mark W.; Patterson, Michael J.; Soulas, George C.

doi:10.2514/6.2010-6779

Cited by 27 publications

(52 citation statements)

References 10 publications

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“…However, the current density dropoff on the outer side of the profile occurs more rapidly at higher beam currents. This is consistent with previous measurements on NEXT using a similar set of ion optics, which showed that beam divergence decreased with increasing beam current at 1179 V. 6 Figure 17 shows that the dropoff also occurs further from thruster centerline at higher beam currents, an indication that the beam itself is flatter at these conditions. The normalized value of current density at thruster centerline monatonically increases with increasing beam current.…”

Section: Comparisons At Constant Beam Voltage and Currentsupporting

confidence: 81%

“…On the outer side of the peak, however, the current density drops off most rapidly at moderate beam voltages around 679 V. The reason for this is due to a combination of beam divergence and CEX population effects. Previous measurements on NEXT using a similar set of ion optics have shown that at a beam current of 1.20 A, the beam divergence was minimized at a beam voltage of 679 V. 6 This is consistent with the data on the outer side of the peak current density, which shows the most rapid falloff occurring around 679 V -a more rapid falloff is indicative of a more collimated beam. Thus, the trend on the outer side of the profile is attributed to beam divergence effects.…”

Section: Comparisons At Constant Beam Voltage and Currentsupporting

confidence: 79%

“…These axial positions were measured from the geometric center of the optics to the Faraday probe along thruster centerline, and were chosen to mimic measurement locations from a prior ion current density study performed on NEXT. 6 Scans were also taken in the axial direction in the vertical plane of thruster centerline to characterize how the ion current density decays with downstream distance.…”

Section: Plume Faraday Probementioning

confidence: 99%

See 2 more Smart Citations

Current Density Measurements of an Annular-Geometry Ion Engine

Shastry

Patterson

Herman

et al. 2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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The concept of the annular-geometry ion engine, or AGI-Engine, has been shown to have many potential benefits when scaling electric propulsion technologies to higher power. However, the necessary asymmetric location of the discharge cathode away from thruster centerline could potentially lead to non-uniformities in the discharge not present in conventional geometry ion thrusters. In an effort to characterize the degree of this potential non-uniformity, a number of current density measurements were taken on a breadboard AGI-Engine. Fourteen button probes were used to measure the ion current density of the discharge along a perforated electrode that replaced the ion optics during conditions of simulated beam extraction. Three Faraday probes spaced apart in the vertical direction were also used in a separate test to interrogate the plume of the AGI-Engine during true beam extraction. It was determined that both the discharge and the plume of the AGIEngine are highly uniform, with variations under most conditions limited to ±10% of the average current density in the discharge and ±5% of the average current density in the plume. Beam flatness parameter measured 30 mm from the ion optics ranged from 0.85 -0.95, and overall uniformity was shown to generally increase with increasing discharge and beam currents. These measurements indicate that the plasma is highly uniform despite the asymmetric location of the discharge cathode.

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Section: Comparisons At Constant Beam Voltage and Currentsupporting

confidence: 81%

Section: Comparisons At Constant Beam Voltage and Currentsupporting

confidence: 79%

Section: Plume Faraday Probementioning

confidence: 99%

See 1 more Smart Citation

Current Density Measurements of an Annular-Geometry Ion Engine

Shastry

Patterson

Herman

et al. 2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

Self Cite

View full text Add to dashboard Cite

show abstract

“…Examinations of the beam current density and xenon charge-state distribution as functions of position on the accelerator grid have been completed. [18] The angular dependence of beam current was measured at intermediate and far-field distances to assist with plume modeling and to evaluate the thrust loss due to beam divergence. Thrust correction factors were derived from the data.…”

Section: Nasa's Evolutionary Xenon Thruster (Next)mentioning

confidence: 99%

The status of spacecraft bus and platform technology development under the NASA ISPT program

Anderson

Munk

Pencil

et al. 2014

2014 IEEE Aerospace Conference

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“…Although using the measured thrust defeats one of the original purpose of the phenomenological model (which is to provide a check on the thrustderived anode efficiency), it will give us a more realistic check on how well we have chosen our integration limits. Equation (8) shows how the mass utilization efficiency is estimated from the measured thrust.…”

Section: Efficiency Modelmentioning

confidence: 99%

Farfield Ion Current Density Measurements before and after the NASA HiVHAc EDU2 Vibration Test

Huang¹,

Kamhawi²,

Shastry³

2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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There is an increasing need to characterize the plasma plume of the NASA HiVHAc thruster in order to better understand the plasma physics and to obtain data for spacecraft interaction studies. To address this need, the HiVHAc research team is in the process of developing a number of plume diagnostic systems. This paper presents the initial results of the farfield current density probe diagnostic system. Farfield current density measurements were carried out before and after a vibration test of the HiVHAc engineering development unit 2 that simulate typical launch conditions. The main purposes of the current density measurements were to evaluate the thruster plume divergence and to investigate any changes in the plasma plume that may occur as a result of the vibration test. Radial sweeps, as opposed to the traditional polar sweeps, were performed during these tests. The chargedweighted divergence angles were found to vary from 16 to 28 degrees. Charge density profiles measured pre-and post-vibration-test were found to be in excellent agreement. This result, alongside thrust measurements reported in a companion paper, confirm that the operation of the HiVHAc engineering development unit 2 were not altered by fulllevel/random vibration testing.

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Spatially-Resolved Beam Current and Charge-State Distributions for the NEXT Ion Engine

Cited by 27 publications

References 10 publications

Current Density Measurements of an Annular-Geometry Ion Engine

Current Density Measurements of an Annular-Geometry Ion Engine

The status of spacecraft bus and platform technology development under the NASA ISPT program

Farfield Ion Current Density Measurements before and after the NASA HiVHAc EDU2 Vibration Test

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