Magnetic confinement and instability in partially magnetized plasma

Kim, June Young; Jang, Jae Young; Choi, Jae-Young; Wang, Jong-in; Jeong, Won Ik; Elgarhy, Mahmoud A. I.; Go, Geunwoo; Chung, Kyoung-Jae; Hwang, Y. S.

doi:10.1088/1361-6595/abd455

Cited by 28 publications

(17 citation statements)

References 36 publications

(49 reference statements)

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“…These instabilities can cause hindrance in the balance of plasma generation and loss at the edge and hence on plasma confinement. One of such instability is Simon-Hoh instability which may exist in such systems [48].…”

Section: Discussionmentioning

confidence: 99%

A study on the influence of external magnetic field on Nitrogen RF discharge using Langmuir probe and OES methods

Mukherjee¹,

Sharma²,

Chakraborty³

et al. 2022

Phys. Scr.

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This paper reports the study of the effects of an externally applied magnetic field (0-300 G), in the mode transition as well as in the radial and axial variation of different plasma parameters such as electron density, temperature, etc., in nitrogen RF discharge with the help of an RF compensated Langmuir probe (LP). Also, Optical Emission Spectroscopy (OES) study is performed in order to have a good understanding of the properties of plasma at different magnetic fields. Data collected from LP shows all three mode transitions (E, H, and W mode) in presence of magnetic fields whereas for no magnetic field only two modes (E and H) are visible. The measured value of electron density by using LP is further verified and compared theoretically using particle and power balance equations. However, the overall density profile attains a higher value for no magnetic field. This rise in overall density at 0 G field is further explained in terms of EEPF plot and OES analysis. The EEPF plot reveals that the number of high energy electrons is reduced with the application of magnetic fields. Also from OES analysis, it is found that the molecular excitations in N2 second positive system [C 3Πu (νʹ) → B 3Πg (νʺ)] are increased in the presence of magnetic fields whereas with no magnetic field the ionization peak of N2 first negative system and the molecular dissociation peak at 746.8 nm attains the largest value at a certain power. Plasma density values calculated with the OES method at the different magnetic fields and RF power show a similar trend with respect to the density values obtained from the LP method.

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Section: Discussionmentioning

confidence: 99%

A study on the influence of external magnetic field on Nitrogen RF discharge using Langmuir probe and OES methods

Mukherjee¹,

Sharma²,

Chakraborty³

et al. 2022

Phys. Scr.

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“…The strong confinement of charged particles by applied magnetic field aids in producing a high-density plasma, and affects low-pressure gas breakdown, (see schematic in figure 3(c)). The applications that utilize strong magnetic field are the nuclear fusion [28], electric propulsion [29], ion implantation [30], and deposition of thin films [31]. Effects of magnetic field plays a crucial role of the particle transport and gas ionization in the electrical breakdown phenomenon in magnetized discharges.…”

Section: Configurations Of Discharge Sourcesmentioning

confidence: 99%

Review of the gas breakdown physics and nanomaterial-based ionization gas sensors and their applications

Kim

Kaganovich

Lee

2022

Plasma Sources Sci. Technol.

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Ionization gas sensors are a ubiquitous tool that can monitor desired gases or detect abnormalities in real time to protect the environment of living organisms or to maintain clean and/or safe environment in industries. The sensors’ working principle is based on the fingerprinting of the breakdown voltage of one or more target gases using nanostructured materials. Fundamentally, nanomaterial-based ionization-gas sensors operate within a large framework of gas breakdown physics; signifying that an overall understanding of the gas breakdown mechanism is a crucial factor in the technological development of ionization gas sensors. Moreover, many studies have revealed that physical properties of nanomaterials play decisive roles in the gas breakdown physics and the performance of plasma-based gas sensors. Based on this insight, this review provides a comprehensive description of the foundation of both the gas breakdown physics and the nanomaterial-based ionization-gas-sensor technology, as well as introduces research trends on nanomaterial-based ionization gas sensors. The gas breakdown is reviewed, including the classical Townsend discharge theory and modified Paschen curves; and nanomaterial-based-electrodes proposed to improve the performance of ionization gas sensors are introduced. The secondary electron emission at the electrode surface is the key plasma–surface process that affects the performance of ionization gas sensors. Finally, we present our perspectives on possible future directions.

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“…In line with this engineering necessity, academia has designated low-temperature plasma sources with the characteristics of partially magnetized plasma as a new classification system called E × B discharge sources [1]. In the operation of these sources, the particle motion is coupled with externally applied electric and magnetic fields, and many physical phenomena have been reported in E × B devices such as transport and magnetic confinement [2][3][4][5], instability [6][7][8][9], and thermodynamics [10][11][12][13][14][15].…”

mentioning

confidence: 99%

“…Generally, electrons are azimuthally rotated with closed E × B drift loops that contribute to an efficient gas discharge in the case of Hall thrusters [16] and magnetron sputtering devices [17]. In contrast, electrons are confined along the magnetic field line in the E × B Penning discharge source [4]. The heating and energy relaxation of the beam electrons in the E × B Penning device is concentrated in the central plasma column along the magnetic field line, and the electrons bounce back and forth when they encounter an axial cathode sheath.…”

mentioning

confidence: 99%

“…The E × B Penning source used in this study has a cylindrical area with two axial (hot-cathode and anti-cathode) and radial (electrode 1 and 2) boundaries (figures 1(a) and (b)). The mechanism by which discharges were initiated began with the release of thermionic electrons from the indirectly heated hot-cathode [4]. Next, beam electrons were generated by the acceleration of the thermionic electrons with a kinetic energy equivalent to the voltage of the sheath potential of the hotcathode.…”

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confidence: 99%

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Efficiency improvement of an E × B Penning discharge source by enhanced cross-field transport of electrons

Kim

Choi

et al. 2022

Plasma Sources Sci. Technol.

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Precise control of the particle motion in externally applied electric and magnetic fields is of great significance in the development of the E×B source to generate high-density plasma and deliver a stable ion beam current. Especially, in the E×B Penning discharge source, the heating and energy relaxation of the beam electrons is concentrated in the plasma column along the magnetic field line. Plasma researchers have thus far focused on the relevant physical phenomena of the partially magnetized plasma that arises from the gradient of the plasma properties in the E×B Penning source. Here, we point out that current methods of radially centered electron confinement do not guarantee efficient ion beam extraction, and newly introduce the improvement of the efficiency of a cylindrical E×B Penning source targeting radial extraction of ion beam. We concentrate on the method to enhance the cross-field transport of electrons toward the extraction region. The generation of a spatially asymmetric sheath structure allows the beam and energetic electrons to be transported to the extraction region via the E×B drift of the electrons. The transported electrons contribute to expansion of the electron heating and ionization regions to the extraction region by breaking of axial symmetry of the sheath, thereby increasing the temperature and density of the electrons in the extraction region as the magnetic field strength increases. The enhanced discharge efficiency defined as the ratio of the electron density to the discharge current is noticeable, recording approximately twice the improved efficiency compared to the conventional mode with symmetric sheath structure.

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Magnetic confinement and instability in partially magnetized plasma

Cited by 28 publications

References 36 publications

A study on the influence of external magnetic field on Nitrogen RF discharge using Langmuir probe and OES methods

A study on the influence of external magnetic field on Nitrogen RF discharge using Langmuir probe and OES methods

Review of the gas breakdown physics and nanomaterial-based ionization gas sensors and their applications

Efficiency improvement of an E × B Penning discharge source by enhanced cross-field transport of electrons

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