Axial profiles of argon helicon plasma by optical emission spectroscope and Langmuir probe

Zhang, Zun; Yang, Kaiyi; Tan, Chang; Cui, Ruilin; Ouyang, Jiting

doi:10.1088/2058-6272/ab175b

Cited by 15 publications

(24 citation statements)

References 35 publications

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“…The efficiency of ionization was promoted accordingly. This characteristic of mode transition was reported previously by our group [30–32] as well as the others [34–36].…”

Section: Resultssupporting

confidence: 87%

“…Since 811.53 nm emission from the transition 3p 5 the DL on axis. Besides, the intensity of 811.53 nm line can be converted to the electron density by certain relations [31,32]. Hence the corresponding electron density is also displayed here in Figure 3b.…”

Section: Experiments and Resultsmentioning

confidence: 97%

“…Since 811.53 nm emission from the transition 3p 5 ( 2 P 0 3/2 )4p[5/2] 3 → 3p 5 ( 2 P 0 3/2 )4s[3/2] 0 2 is correlated with the density of metastable state argon atoms as well as the electron density [30], result of Figure 3b also approximately indicates the distribution of electron density, roughly the plasma density, across the DL on axis. Besides, the intensity of 811.53 nm line can be converted to the electron density by certain relations [31, 32]. Hence the corresponding electron density is also displayed here in Figure 3b.…”

Section: Resultsmentioning

confidence: 99%

“…With this method, the plasma potential can be obtained and applied into the analysis of the DL. The method for measuring the optical spectrum of Ar helicon plasma is local optical emission spectrum [31,32]. The optical spectrum is collected by a probe comprised of a hollow ceramic cylindrical tube 5 mm in diameter and a thin optical fibre fixed inside.…”

Section: Experimental Set-up and Diagnostic Methodsmentioning

confidence: 99%

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Effect of magnetic field on double layer in argon helicon plasma

et al. 2020

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The electric double layer in argon helicon plasma by using floating electrostatic probe and local optical emission spectroscopy under different external magnetic field was investigated. Results show that electrons generated in the plasma source can be magnetized by the magnetic field and transported by the gradient of diverging magnetic field in the diffusion chamber, giving rise to the hollowed distribution of electron temperature. The electron temperature on axis has a sudden decrease, leading to the sudden decrease of plasma density as well as the plasma potential, forming a double layer structure. The position of double layer moves along with the position of diverging magnetic field, and the potential drop increases along with the strength of magnetic field. The structure of the external magnetic field plays the decisive factor for the double layer in helicon plasma.

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“…The efficiency of ionization was promoted accordingly. This characteristic of mode transition was reported previously by our group [30–32] as well as the others [34–36].…”

Section: Resultssupporting

confidence: 87%

Section: Experiments and Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Experimental Set-up and Diagnostic Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Effect of magnetic field on double layer in argon helicon plasma

et al. 2020

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“…The optical method has the advantages of having no scan voltage, and being unaffected by the plasma potential oscillations and magnetic and electric fields [17,18]. Therefore, the optical method causes little disturbance to the plasma and can reflect plasma properties such as electron temperatures and densities by using the collisional-radiative (CR) model [19][20][21][22][23][24][25][26][27]. Moreover, the optical method can distinguish electrons with different energies by their emission lines.…”

Section: Introductionmentioning

confidence: 99%

Electron population properties with different energies in a helicon plasma source

Zhang¹,

Zhang²,

Tang³

et al. 2020

Plasma Sci. Technol.

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The characteristics of electrons play a dominant role in determining the ionization and acceleration processes of plasmas. Compared with electrostatic diagnostics, the optical method is independent of the radio frequency (RF) noise, magnetic field, and electric field. In this paper, an optical emission spectroscope was used to determine the plasma emission spectra, electron excitation energy population distributions (EEEPDs), growth rates of low-energy and high-energy electrons, and their intensity jumps with input powers. The 56 emission lines with the highest signal-to-noise ratio and their corresponding electron excitation energy were used for the translation of the spectrum into EEEPD. One discrete EEEPD has two clear different regions, namely the low-energy electron excitation region (neutral lines with threshold energy of 13–15 eV) and the high-energy electron excitation region (ionic lines with threshold energy ≥19 eV). The EEEPD variations with different diameters of discharge tubes (20 mm, 40 mm, and 60 mm) and different input RF powers (200–1800 W) were investigated. By normalized intensity comparison of the ionic and neutral lines, the growth rate of the ionic population was higher than the neutral one, especially when the tube diameter was less than 40 mm and the input power was higher than 1000 W. Moreover, we found that the intensities of low-energy electrons and high-energy electrons jump at different input powers from inductively coupled (H) mode to helicon (W) mode; therefore, the determination of W mode needs to be carefully considered.

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Striations in helicon-type argon plasma

Zhu

Cui

et al. 2021

Physics of Plasmas

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In this paper, two types of stationary striations appearing in an argon helicon plasma source are presented. The formation and features of the striations were investigated experimentally under different conditions, including RF power, gas pressure, and external magnetic field. The results show that the striation spacing decreases as the gas pressure increases but does not change significantly along with the magnetic field and the RF power. It is suggested that these striations are strongly related to the non-local effect of electron kinetics in the plasma channel with a weak electric field. The different pressures in downstream and antenna regions will lead to different types of striations in an argon helicon plasma source.

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Axial profiles of argon helicon plasma by optical emission spectroscope and Langmuir probe

Cited by 15 publications

References 35 publications

Effect of magnetic field on double layer in argon helicon plasma

Effect of magnetic field on double layer in argon helicon plasma

Electron population properties with different energies in a helicon plasma source

Striations in helicon-type argon plasma

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