Empirical laws of particle extraction from single-grid source of bipolar ion-electron flow

Dudin, S.V.; Rafalskyi, Dmytro

doi:10.1063/1.4767241

Cited by 12 publications

(15 citation statements)

References 16 publications

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“…22 In principle, replacing the smaller electrode by a conductive grid allows to simultaneously accelerate ions through the grid and co-extract electrons with an equal flux; however, such a configuration is found to have low efficiency and leads to plasma contamination by metal ions. 23,24 The maximum ion energy and thus applied voltage for this system is limited by quite small values (around 200-300 eV). 24 Recently, a further concept based on a self-bias effect free of mentioned drawbacks has been proposed.…”

Section: The Rf Self-bias Acceleration Conceptmentioning

confidence: 99%

“…23,24 The maximum ion energy and thus applied voltage for this system is limited by quite small values (around 200-300 eV). 24 Recently, a further concept based on a self-bias effect free of mentioned drawbacks has been proposed. 8,9 In this concept, the RF-DC combined space charge sheath is located between two grids, thus the focusing plasma meniscus can be formed in front of each extraction aperture and grid is not bombarded by high-energy ions.…”

Section: The Rf Self-bias Acceleration Conceptmentioning

confidence: 99%

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Plasma acceleration using a radio frequency self-bias effect

Rafalskyi

Aanesland

2015

Physics of Plasmas

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International audienceIn this work plasma acceleration using a RF self-bias effect is experimentally studied. The experiments are conducted using a novel plasma accelerator system, called Neptune, consisting of an inductively coupled plasma source and a RF-biased set of grids. The plasma accelerator can operate in a steady state mode, producing a plasma flow with separately controlled plasma flux and velocity without any magnetic configuration. The operating pressure at the source output is as low as 0.2 mTorr and can further be decreased. The ion and electron flows are investigated by measuring the ion and electron energy distribution functions both space resolved and with different orientations with respect to the flow direction. It is found that the flow of electrons from the source is highly anisotropic and directed along the ion flow and this global flow of accelerated plasma is well localized in the plasma transport chamber. The maximum flux is about 7.5·1015 ions s−1 m−2 (at standard conditions) on the axis and decreasing to almost zero at a radial distances of more than 15 cm from the flow axis. Varying the RF acceleration voltage in the range 20350 V, the plasma flow velocity can be changed between 10 and 35 km/s. The system is prospective for different technology such as space propulsion and surface modification and also interesting for fundamental studies for space-related plasma simulations and investigation of the dynamo effect using accelerated rotating plasmas. I. INTRODUC

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Section: The Rf Self-bias Acceleration Conceptmentioning

confidence: 99%

Section: The Rf Self-bias Acceleration Conceptmentioning

confidence: 99%

Plasma acceleration using a radio frequency self-bias effect

Rafalskyi

Aanesland

2015

Physics of Plasmas

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“…Replacing the smaller driven electrode by a grid allows the generation of coincident ion-electron flow, as shown in a single-grid system [4]. As mentioned in the introduction, single-grid systems are strongly limited by grid sputtering and low source efficiency [16].…”

Section: The Neptune Rf Acceleration Conceptmentioning

confidence: 99%

“…Figure 2 shows the expected RF plasma potential waveform with respect to the grounded second grid. A φ cr is the plasma potential corresponding to the sheath collapse, and can be estimated using the Child's law for the given aperture dimensions and ion flux from plasma [15,16].…”

Section: The Neptune Rf Acceleration Conceptmentioning

confidence: 99%

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Coincident ion acceleration and electron extraction for space propulsion using the self-bias formed on a set of RF biased grids bounding a plasma source

Rafalskyi¹,

Aanesland²

2014

J. Phys. D: Appl. Phys.

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We propose an alternative method to accelerate ions in classical gridded ion thrusters and ion sources such that co-extracted electrons from the source may provide beam space charge neutralization. In this way there is no need for an additional electron neutralizer. The method consists of applying RF voltage to a two-grid acceleration system via a blocking capacitor. Due to the unequal effective area of the two grids in contact with the plasma, a DC self-bias is formed, rectifying the applied RF voltage. As a result, ions are continuously accelerated within the grid system while electrons are emitted in brief instants within the RF period when the RF space charge sheath collapses. This paper presents the first experimental results and a proof-ofprinciple. Experiments are carried out using the Neptune thruster prototype which is a gridded Inductively Coupled Plasma (ICP) source operated at 4 MHz, attached to a larger beam propagation chamber. The RF power supply is used both for the ICP discharge (plasma generation) and powering the acceleration grids via a capacitor for ion acceleration and electron extraction without any DC power supplies. The ion and electron energies, particle flux and densities are measured using retarding field energy analyzers (RFEA), Langmuir probes and a large beam target. The system is operating in Argon and N 2. The DC self-bias is found to be generated within the gridded extraction system in all the range of operating conditions. Broad quasi-neutral ion-electron beams are measured in the downstream chamber with energies up to 400 eV. The beams from the RF acceleration method are compared with classical DC acceleration with an additional external electron neutralizer. It is found that the two acceleration techniques provide similar performance, but the ion energy distribution function from RF acceleration is broader while the floating potential of the beam is lower than for the DC accelerated beam.

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Direct current-self-sustained non-ambipolar plasma at low pressure

Chen¹,

Chen²,

Funk³

2013

Applied Physics Letters

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For decades, non-ambipolar diffusion has been observed and studied in laboratory plasmas that contain a double layer. However, self-sustained non-ambipolar plasma has yet to be demonstrated. This article reports the method and results for achieving such a condition at low pressure, with a wide power range (as low as 6 W). The findings reveal that to achieve self-sustained non-ambipolar plasma, both the balance between electron and ion heating and the space-potential gradient are critical. The plasma reactor developed in this work has potential applications that include microelectronic surface processing and space propulsion, via space-charge-neutral plasma-beam thruster, when operated in the high power regime.

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Empirical laws of particle extraction from single-grid source of bipolar ion-electron flow

Cited by 12 publications

References 16 publications

Plasma acceleration using a radio frequency self-bias effect

Plasma acceleration using a radio frequency self-bias effect

Coincident ion acceleration and electron extraction for space propulsion using the self-bias formed on a set of RF biased grids bounding a plasma source

Direct current-self-sustained non-ambipolar plasma at low pressure

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