Wafer-level integrated electrospray emitters for a pumpless microthruster system operating in high efficiency ion-mode

Ataman, Çağlar; Dandavino, Simon; Shea, Herbert

doi:10.1109/memsys.2012.6170394

Cited by 3 publications

(4 citation statements)

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“…After characterizing the ToF system and the ion guide for needle emitters, the system was used for spray characterization of capillary-fed internally wetted microfabricated emitters, such as the one shown in [32,55] (see Supplementary Figure S3 for SEM image). A microfabricated reservoir, created just beneath the capillary emitter, is first filled with ionic liquid and the liquid then reaches the tip of the emitter by capillary process.…”

Section: Experimental Results Using Microfabricated Capillary Emittersmentioning

confidence: 99%

“…The extraction voltage is then applied. We have previously observed that these devices emit currents of up ±2 μA [35,55], in mixed iondroplet mode with emission half-angle of 40° [32] at operating voltages between ±700 V and 1000 V. Retarding potential analysis (RPA) of these devices has previously shown that the kinetic energy of emission can have nearly 10% deficit from the applied emitter potential V em [35,36]. There can also be secondary peaks [35,36] corresponding to ion defragmentation in which dimers can break into neutral molecules and a monomers during their flight and share the kinetic energy according to the ratio of their masses.…”

Section: Experimental Results Using Microfabricated Capillary Emittersmentioning

confidence: 99%

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A ToF-MS with a Highly Efficient Electrostatic Ion Guide for Characterization of Ionic Liquid Electrospray Sources

Chakraborty

Ataman

Courtney

et al. 2014

J. Am. Soc. Mass Spectrom.

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We report on the development of a time-of-flight (ToF) mass spectrometer with a highly efficient electrostatic ion guide for enhancing detectability in ToF mass spectrometry. This 65-cm long ion guide consists of 13 cascaded stages of Einzel lens to collect a large fraction of emitted charges over a wide emission angle and energy spread for time-of-flight measurements. Simulations show that the ion guide can collect 100% of the charges with up to 23° emission half-angle or 30% energy spread irrespective of their specific charge. We demonstrate this ion guide as applied to electrospray ion sources. Experiments performed with tungsten needle electrospraying the ionic liquid EMI-BF4 showed that up to 80% of the emitted charges could be collected at the end of the flight tube. Flight times of monomers and dimers emitted from the needles were measured in both positive and negative emission polarities. The setup was also used to characterize the electrospray from microfabricated silicon capillary emitters and nearly 30% charges could be collected even from a 40(°) emission half-angle. This setup can thus increase the fraction of charge collection for ToF measurement and spray characteristics can be obtained from a very large fraction of the emission in real time.

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Section: Experimental Results Using Microfabricated Capillary Emittersmentioning

confidence: 99%

Section: Experimental Results Using Microfabricated Capillary Emittersmentioning

confidence: 99%

A ToF-MS with a Highly Efficient Electrostatic Ion Guide for Characterization of Ionic Liquid Electrospray Sources

Chakraborty

Ataman

Courtney

et al. 2014

J. Am. Soc. Mass Spectrom.

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“…Previous thruster prototypes produced by our group were comprised of microfabricated arrays of 19 bead-filled capillary emitters [13,14] with a single extraction stage. Our latest generation uses a simpler, improved emitter fabrication process and wafer-level bonding of the electrodes, which we had proposed earlier [15]. The new process permits the large scale fabrication of high aspect ratio capillaries with the smallest <10 µm inner diameters to date.…”

Section: Introductionmentioning

confidence: 99%

“…Our latest generation uses a simpler, improved emitter fabrication process and wafer-level bonding of the electrodes, which we had proposed earlier [15]. The new process permits the large scale fabrication of high aspect ratio capillaries with the smallest <10 µm inner diameters to date.…”

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confidence: 99%

Microfabricated electrospray emitter arrays with integrated extractor and accelerator electrodes for the propulsion of small spacecraft

Dandavino¹,

Ataman²,

Ryan³

et al. 2014

J. Micromech. Microeng.

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Microfabricated electrospray thrusters could revolutionize the spacecraft industry by providing efficient propulsion capabilities to micro and nano satellites (1–100 kg). We present the modeling, design, fabrication and characterization of a new generation of devices, for the first time integrating in the fabrication process individual accelerator electrodes capable of focusing and accelerating the emitted sprays. Integrating these electrodes is a key milestone in the development of this technology; in addition to increasing the critical performance metrics of thrust, specific impulse and propulsive efficiency, the accelerators enable a number of new system features such as power tuning and thrust vectoring and balancing. Through microfabrication, we produced high density arrays (213 emitters cm−2) of capillary emitters, assembling them at wafer-level with an extractor/accelerator electrode pair separated by micro-sandblasted glass. Through IV measurements, we could confirm that acceleration could be decoupled from the extraction of the spray—an important element towards the flexibility of this technology. We present the largest reported internally fed microfabricated arrays operation, with 127 emitters spraying in parallel, for a total beam of 10–30 µA composed by 95% of ions. Effective beam focusing was also demonstrated, with plume half-angles being reduced from approximately 30° to 15° with 2000 V acceleration. Based on these results, we predict, with 3000 V acceleration, thrust per emitter of 38.4 nN, specific impulse of 1103 s and a propulsive efficiency of 22% with <1 mW/emitter power consumption.

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Progress Towards a Miniaturized Electrospray Thruster for Flexible Propulsion of Small Spacecraft

Dandavino¹,

Ataman²,

Chakraborty³

et al. 2012

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

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Miniaturized electrical thrusters based on electrospray (or colloid) emitters could revolutionize the spacecraft industry by providing efficient propulsion capabilities to micro and nano satellites (1-100 kg). We report on our recent advances in the development of this technology within the MicroThrust (www.microthrust.eu) European consortium. We present the design and operation of the currently fabricated and next generation emitter arrays, describing their microfabrication process and measured performance. The emitters are out-of-plane internally fed capillaries micromachined in monolithic silicon. They are 100 µm tall and have an inner diameter of 5-10 µm. We operate the devices in both unipolar and bi-polar modes and find that the latest devices operate in a mixed regime, with the emitted spray a composition of ions and droplets. Their specific impulse is consequently in the few hundred seconds, highlighting the need for higher impedance, smaller emitters. Onset voltages are in the range of 800-850V for 200 µm inner diameter extractors, current levels for 19 emitter arrays of 2-3 µA. Preliminary analysis hints to plume half-angles of 35-40 • , although these values depend on the operation mode and beam composition. Nomenclature g Standard gravity (9.80665 m/s 2 )

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Wafer-level integrated electrospray emitters for a pumpless microthruster system operating in high efficiency ion-mode

Cited by 3 publications

References 2 publications

A ToF-MS with a Highly Efficient Electrostatic Ion Guide for Characterization of Ionic Liquid Electrospray Sources

A ToF-MS with a Highly Efficient Electrostatic Ion Guide for Characterization of Ionic Liquid Electrospray Sources

Microfabricated electrospray emitter arrays with integrated extractor and accelerator electrodes for the propulsion of small spacecraft

Progress Towards a Miniaturized Electrospray Thruster for Flexible Propulsion of Small Spacecraft

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