Construction of Larger Area Density-Uniform Plasma with Collisional Inductively Coupled Plasma Cells

A simple diagnostic tool for density measurements in plasma with a certain spatial resolution is proposed in this paper. It uses the emission characteristics of monopole antenna to determine the dielectic property of plasma ε = 1 − f 2 p /f 2 , with the fp electron plasma frequency related to plasma density. We immersed a monopole antenna probe into plasma and introduced a microwave signal via a network analyzer. When the emitted power is maximized, the reflected power is minimized and there occurs a resonance. Since can be derived from the resonant frequency, this is actually a method to measure the absolute electron density. Validated by a comparison with the amended Langmuir double-probe method, the monopole antenna probe is valuable. In addition, it is free from the difficulties, such as fluctuation in plasma potential.

“…3. As the distance from the plasma center increases from z = 22 cm to z = 26 cm, the resonance frequency decreases, which matches the character of inductively coupled plasma [10] .…”

Section: Resultssupporting

confidence: 58%

Monopole Antenna Probe for Density Measurements in Cold Plasmas

Wang¹,

Li²,

Wang³

et al. 2011

“…It may be caused by the narrow range of appropriate density and the relatively higher gas pressure. But the linear enhancement has been reported by some authors [14,18] , though it was not directly pointed out [14] .…”

Section: Nonlinear Enhancement Of Plasma Densitymentioning

confidence: 95%

“…Owing to their small structure, they are easy to be placed. For example, multiple internal ICPs [17,18] were applied well in generation of large-area plasma. In this paper, another method to build plasma is proposed, which depends on the nonlinear enhancement effect of plasma density that occurs when multiple internal antennas discharge simultaneously.…”

Section: Introductionmentioning

confidence: 99%

A Method to Construct Plasma with Nonlinear Density Enhancement Effect in Multiple Internal Inductively Coupled Plasmas

Chen¹,

Li²,

Liu³

et al. 2011

A method is proposed to built up plasma based on a nonlinear enhancement phenomenon of plasma density with discharge by multiple internal antennas simultaneously. It turns out that the plasma density under multiple sources is higher than the linear summation of the density under each source. This effect is helpful to reduce the fast exponential decay of plasma density in single internal inductively coupled plasma source and generating a larger-area plasma with multiple internal inductively coupled plasma sources. After a careful study on the balance between the enhancement and the decay of plasma density in experiments, a plasma is built up by four sources, which proves the feasibility of this method. According to the method, more sources and more intensive enhancement effect can be employed to further build up a high-density, large-area plasma for different applications.

“…The preferred gas in the literature survey above is argon and the preferred pressure range is between 1 and 10 Pa. Multiple coils, however, may also be installed inside the chamber and operate at pressures as high as 300 Pa, as reported by Liang et al [28]. The arcing, which should appear at this pressure under ordinary conditions, was avoided by placing each coil in a tube kept at atmospheric pressure because the tubes were open to the outer environment through the hollow sustaining pole.…”

Section: Introductionmentioning

confidence: 99%

“…The arcing, which should appear at this pressure under ordinary conditions, was avoided by placing each coil in a tube kept at atmospheric pressure because the tubes were open to the outer environment through the hollow sustaining pole. With this innovative design, the authors [28] managed to sustain dense uniform plasma within the coils in a range of pressures between 10 and 300 Pa. The electron temperature was close to 1.5 eV and the density exceeded 10 19 m −3 at elevated pressures.…”

Section: Introductionmentioning

confidence: 99%

Power characteristics of multiple inductively coupled RF discharges inside a metallic chamber

Lojen¹,

Zaplotnik²,

Mozetič³

et al. 2021

The characteristics of an innovative configuration of multiple radiofrequency (RF) coils immersed in a large metallic chamber are presented. Water-cooled copper coils were mounted within the slits of double-walled glass tubes, which were immersed into a stainless-steel chamber. The coils were connected in parallel to a gamma-type matching network, powered by an RF generator operating at industrial frequency. Adjustable leads enabled optimisation of the line impedances and thus uniformly distributed RF power across the four coils. Transitions from E- to H-mode and vice versa were measured for all coils at various oxygen pressures between 5 and 25 Pa. A uniform plasma was sustained in H-mode at the absorbed power threshold, which increased monotonously with increasing pressure in the metallic chamber. All coils exhibit the same E- to H-mode transition hysteresis and need the same amount of power for transitioning from E- to H-mode. The setup enables maintaining uniform plasma in virtually any number of coils at high power without the risk of arcing and without the dead volume typical for a classical configuration with coils mounted outside the metallic chamber.