Design Study for a Planet-Finding Space Interferometer

Martin, Stefan; Scharf, Daniel P.; Wirz, Richard E.; Lay, Oliver P.; McKinstry, David; Mennesson, Bertrand; Purcell, G. H.; Rodriguez, Jose Israel; Scherr, L.; Smith, James R.; Wayne, Leonard

doi:10.1109/aero.2008.4526410

Cited by 13 publications

(7 citation statements)

References 13 publications

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“…Miniature ion thrusters (typically 1-3 cm diameter) are an attractive option for secondary propulsion for larger spacecraft, for formation flying and attitude control, or for primary propulsion to execute orbit transfers and maintenance in smaller spacecraft. [1][2][3] To date, discharges using ring-cusp designs have exhibited the best efficiency for ion thrusters at all scales. 4 However, smaller ion thrusters exhibit relatively low discharge efficiencies due to the inherent increase in the surface area-to-volume ratio of the plasma generation (i.e., discharge) chamber.…”

Section: Introductionmentioning

confidence: 99%

Miniature ion thruster ring-cusp discharge performance and behavior

Dankongkakul

Wirz

2017

Journal of Applied Physics

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Miniature ion thrusters are an attractive option for a wide range of space missions due to their low power levels and high specific impulse. Thrusters using ring-cusp plasma discharges promise the highest performance, but are still limited by the challenges of efficiently maintaining a plasma discharge at such small scales (typically 1-3 cm diameter). This effort significantly advances the understanding of miniature-scale plasma discharges by comparing the performance and xenon plasma confinement behavior for 3-ring, 4-ring, and 5-ring cusp by using the 3 cm Miniature Xenon Ion thruster as a modifiable platform. By measuring and comparing the plasma and electron energy distribution maps throughout the discharge, we find that miniature ring-cusp plasma behavior is dominated by the high magnetic fields from the cusps; this can lead to high loss rates of high-energy primary electrons to the anode walls. However, the primary electron confinement was shown to considerably improve by imposing an axial magnetic field or by using cathode terminating cusps, which led to increases in the discharge efficiency of up to 50%. Even though these design modifications still present some challenges, they show promise to bypassing what were previously seen as inherent limitations to ring-cusp discharge efficiency at miniature scales. Published by AIP Publishing. https://doi

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Section: Introductionmentioning

confidence: 99%

Miniature ion thruster ring-cusp discharge performance and behavior

Dankongkakul

Wirz

2017

Journal of Applied Physics

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“…Subsequently a precision maneuvers milestone representative of TPF-I requirements was demonstrated using both robots, that showed initialization, maneuvering, and operation in a collision free manner, all autonomously. A series of experiments with the robots demonstrated formation rotations while maintaining relative position control to 5 cm rms [40] . It was shown that in the comparatively benign environment of space, the performance of the robots would exceed TPF-I flight requirements.…”

Section: Formation Flyingmentioning

confidence: 98%

“…The addit sizes pointed structure of th er. When the beam combiner an be achieved plane combine to temperature ment [39] , keepin yload was redu d Missions Co mma design [40] , 6:1 aspect ratio ssion cost of $3 mma design. (Co…”

Section: Nullinmentioning

confidence: 99%

TPF-Interferometer: a decade of development in exoplanet detection technology

et al. 2011

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The last decade has seen great advances in interferometric nulling technology, propelled at first by the SIM and KECK nulling programs and then by the Terrestrial Planet Finder Interferometer (TPF-I). In the infrared at N-band (using a CO 2 laser at 10.6 micron wavelength) the first million to one nulls were reported on a KECK testbed in 2003. For TPF-I, nulls needed to be both deep and broadband, and a suite of testbeds was designed and built to study all aspects of achromatic nulling and system implementation, including formation flying technology. Also, observatory designs were drawn up and studied against performance models. Modeling revealed that natural variations in the alignment and control of the optical system produced an "instability noise" signal and this realization eventually led to a redesign of the layout to a rectangular formation. The complexity of the early TPF-I spacecraft design was mitigated by the infusion of ideas from Europe and produced the current X-Array design which utilizes simple reflectors to form the apertures together with a stretched three dimensional formation geometry. This paper summarizes the main achievements of the infrared nulling technology program including the development of adaptive nulling for broadband performance and the demonstration of starlight suppression by 100 million to one.

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“…A micro-scale thruster of this size is attractive for large delta-V missions using small spacecraft and for formation flying and control for larger spacecraft. 1,2,3 Magnetic cusp confinement of plasma at conducting surfaces involves interactions between a divergent magnetic field, multiple plasma species, and the sheath conditions near the surface. 4 Much of the research on cusp confinement has been performed using relatively larger plasma discharges with free-standing electromagnetic "picket fence" and spindle cusps far from the anode 5,6,7,8 or multi-magnet ring and line cusps for permanent magnet 1 Assistant Professor, UCLA Mechanical and Aerospace Engineering, AIAA Senior Member, wirz@ucla.edu.…”

Section: Introductionmentioning

confidence: 99%

Near-Surface Cusp Confinement for Weakly Ionized Plasma

Wirz¹,

Araki²,

Dankongkakul³

2012

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

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For this study, we use a combined experimental and computational approach to investigate the near-surface dynamics and structure of plasma confined by a permanent magnet cusp. Improved understanding in this region allows electric propulsion designers to take advantage of cusp confinement for micro-scale discharges (≤ 1 cm), enabling high performance microthrusters that are attractive for both microsatellite and formation flying missions. An electron gun experiment designed specifically for this effort provides detailed data on the plasma for a single permanent magnet cusp for electron-only conditions and multispecies (electron, neutral, and ion) weakly ionized conditions. For these experimental conditions, a multispecies particle-in-cell model is developed that uses an adaptive mesh and analytical solutions for permanent magnets to provide high resolution for particle motion and interactions in the cusp region. Results from the experiment and model agree well and are consistent with existing theory for the "leak radius" at the cusp. Nomenclature a = coefficients for 2D quadratic equation A = amplitude of oscillation dS = differential area along a surface, m 2 E = electric field, V/m E = particle energy, eV E 0 = atomic unit of energy (= 27.21eV) m = particle mass, kg q = charge, C r = radial position, m r l = leak radius, mm R = error of the 2D quadratic equation, V t = time, s U = random number between 0 to 1 v = particle velocity, m/s w l = leak width, mm z = axial position, m Subscripts i = initial k = cell number n = number of neighboring cells f = final Symbols β = magnetic pressure Δt = time step, s ρ h , ρ e , ρ i = hybrid, electron, and ion gyroradii ρ p , ρ s = primary and secondary electron gyroradii φ = electric potential, V χ = deflection angle, rad

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Design Study for a Planet-Finding Space Interferometer

Cited by 13 publications

References 13 publications

Miniature ion thruster ring-cusp discharge performance and behavior

Miniature ion thruster ring-cusp discharge performance and behavior

TPF-Interferometer: a decade of development in exoplanet detection technology

Near-Surface Cusp Confinement for Weakly Ionized Plasma

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