The Polaris Linear Plasma Device

Antar, G.; Younes, J.; Darwish, M.; Costantine, J.; Roumieh, Mohamad; Habchi, Charbel

doi:10.1109/tps.2021.3070638

Cited by 3 publications

(4 citation statements)

References 28 publications

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“…The formation of the blue core was enhanced by a higher magnetic field [46]. Chi et al [37] also found the influence of neutral pressure on mode transition, and Antar et al [47] proved the dependence of the blue core on neutral pressure.…”

Section: Introductionmentioning

confidence: 96%

Effect of neutral pressure on the blue core in Ar helicon plasma under an inhomogeneous magnetic field

Wang

Liu²,

Sun³

et al. 2023

Plasma Sci. Technol.

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The effect of neutral pressure on blue core in Ar helicon plasma under inhomogeneous magnetic field was investigated in this work. The neutral pressure was set to 0.08 Pa, 0.36 Pa and 0.68 Pa. Nikon camera, intensifies charge coupled device (ICCD), optical emission spectrometer (OES), and Langmuir probe were used to diagnose the blue core in helicon plasma. Helicon plasma discharges experienced density jumps from E-, H- to W-mode before power just rose to 200 W. The plasma density increased and maintained the central peak with the increase of neutral pressure. However, the brightness of the blue core gradually decreased. It demonstrated that the relative intensity of Ar II spectral lines and the ionization ratio in the central area were reduced. Radial electron temperature profiles were flattened and became hollow as neutral pressure increased. It demonstrated that increasing the neutral pressure weakened the central heating efficiency dominated by helicon wave and strengthened the edge heating efficiency governed by the TG wave and skin effect. Therefore, the present experiment successfully reveals how the neutral pressure affects the heating mechanism of helicon plasma in inhomogeneous magnetic field.

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Section: Introductionmentioning

confidence: 96%

Effect of neutral pressure on the blue core in Ar helicon plasma under an inhomogeneous magnetic field

Wang

Liu²,

Sun³

et al. 2023

Plasma Sci. Technol.

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“…Polaris is a linear plasma device that is operational at the American University of Beirut [40]. It consists of a stainlesssteel chamber that is approximately 3 m long and 30 cm in diameter.…”

Section: A Polaris Device and The Four Antennasmentioning

confidence: 99%

“…It is installed around a bell-shaped quartz tube, which has a diameter equal to 5 cm. It was shown that the magnetic field in the region where plasma is generated is rather uniform with values that can reach up to 750 G [40].…”

Section: B Rf Plasma Sourcementioning

confidence: 99%

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New Antenna Designs to Boost the Plasma Density in Helicon Sources

Ali

Antar

Costantine

2022

IEEE Trans. Plasma Sci.

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Plasma can be generated using radio frequency (RF) electromagnetic waves for a large variety of applications, such as energy and propulsion generation. Often, the desire is to achieve higher densities for given input power and helicon sources have demonstrated a high efficiency. The design of the antenna that couples the wave plays a major role in the efficiency of generating the plasma particles. Many geometries were studied and compared, but the relationship between the antenna characteristics and the plasma production is still missing. In this article, we identify the power-law dependence between the plasma density and the Gain of an antenna. The latter is determined using numerical simulations in a vacuum, whereas the former is acquired experimentally. The power-law dependence is obtained using four different antenna elements operating under the same experimental conditions on the Polaris linear plasma device. The design a posteriori of a new inductive antenna with a modified quadrifilar helix topology, exhibits not only a higher gain but also confirms the power law. The confirmation of this law will significantly impact the future of many technologies that leverage helicon plasmas.Index Terms-Antenna design, antenna gain, helicon plasma, magnetized plasma devices, radio frequency (RF) antenna. I. INTRODUCTIONP LASMA generation in laboratories has a wide range of applications in a variety of fields like in nuclear fusion [1], space thrusters [2], and plasma processing [3]. A large number of studies are thus dedicated to the production of hot and dense plasma using electromagnetic waves. In 1997, a first review, done by Chen and Boswell [4] presented an account of the understanding of helicon waves and the experimental results. Later in 2015, Chen [5] gave another comprehensive summary of the physics of helicon discharges. In 2018, Shinohara [6] wrote an overview of the experimental results related to radio frequency (RF) sources and their applications.The first helicon plasma source was achieved in an experiment conducted by Lehane and Thoneman [7]. Later on,

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Effect of inhomogeneous magnetic field on blue core in Ar helicon plasma

et al. 2021

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The effect of the inhomogeneous magnetic field on blue core phenomena in helicon plasma is investigated in this work. The permanent magnets (PMs) are used to provide the magnetic field required for generation of helicon plasma, and three different types of the inhomogeneous magnetic field are constructed by changing the permanent magnets positions, which are PM-top/bottom, PM-top, and PM-bottom, respectively. The maximum magnetic field strengths in these three types of inhomogeneous magnetic fields are at both ends (case A), at the upper end (case B), and at the lower end (case C) of the discharge tube, respectively. Nikon camera, an intensified charge coupled device, optical emission spectrometer (OES), and Langmuir probe are used to diagnose the blue core phenomenon in helicon plasma. The electronic excitation temperature is calculated based on optical emission lines captured by OES. Helicon wave discharge is affirmed by mode transition with three discharge stages corresponding to E-, H- and W-modes, respectively. The blue core could occur in the maximum magnetic field strengths located at both ends at around 200 W, at the upper end at around 300 W, and at the lower end at around 400 W. The formation of blue core in the present work can be attributed to the non-uniformity of the inhomogeneous magnetic field. Meanwhile, the radial distribution of plasma density and electron temperature in blue core is different. The plasma density still maintains the on-axis peak, and electron temperature transforms from on-axis peak to off-axis peak due to the skin effect.

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The Polaris Linear Plasma Device

Cited by 3 publications

References 28 publications

Effect of neutral pressure on the blue core in Ar helicon plasma under an inhomogeneous magnetic field

Effect of neutral pressure on the blue core in Ar helicon plasma under an inhomogeneous magnetic field

New Antenna Designs to Boost the Plasma Density in Helicon Sources

Effect of inhomogeneous magnetic field on blue core in Ar helicon plasma

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