Three-dimensional remarkable images of low-pressure H/sub 2/ ICP in E-mode

Abstract

Computerized tomography (CT), in association with optical emission spectroscopy (OES), is used to investigate the three-dimensional image of radio frequency inductively coupled plasma (RF-ICP) in low-pressure hydrogen in E-mode. As a series of CT studies in this paper, we demonstrate a distinct image in H 2 ICP in the E-mode, i.e., the presence of two independent plasmas in a low-pressure region.Index Terms-Computerized tomography, E-mode, hydrogen, inductively coupled plasma, optical emission spectroscopy. I NDUCTIVELY coupled plasmas (ICPs) have been widely used as a high-density plasma source in various applications such as etching, deposition, ashing, surface modification, and mass spectroscopy, etc. ICPs are generally driven by an external current coil which is set at the side wall or top surface of the plasma reactor under a wide range of operating conditions. We have performed systematic studies of the spatiotemporal emission and absorption profile of the ICP by using CT of both the OES and laser absorption spectroscopy (LAS) [1].It is well known that there are two operating modes in ICP. One is a high-density H (inductively coupled) mode sustained by the induced electromagnetic field, and the other is a low-density E (capacitively coupled) mode sustained by the static electric field caused by the local potential difference of the induction coil. The studies of the transition mechanism between the two modes are mostly performed by electrical properties [2]. In the E-mode operated at a low-dissipated power, the electron density is low while the mean energy of electrons with a non-Maxwellian energy distribution is high. In the H-mode, it is exactly the opposite: high power dissipation, operated with a relatively large threshold of the coil current or power. The electron number density in the H-mode is high and the mean energy is lower as compared to those in the E-mode. In addition, in our previous study [4], we visualized that the spatial structure of the E-mode in CF /Ar RF-ICP is quite different from that of the H-mode by using CT-OES. In this paper, we show the presence of two separate plasma region even in a low pressure in H ICP in the E-mode by using CT-OES.Experimental system consists of ICP reactor, photo detector with movable 4-axes robot arm, and wavelength-selectedphoton counting system. The details of the system are described in our previous paper [5]. Plasma is sustained in a quartz cylinder with a diameter of 10 cm and a length of

Atomic spectrometry update. Advances in atomic emission, absorption and fluorescence spectrometry, and related techniques

“…Low pressure ICPs formed with Ar, Kr ad Xe and the mode transitions between E-mode (low power) and H-mode (higher power) have been studied. 273 Likewise, computer tomography has been used 274 to obtain images of a low pressure hydrogen ICP operated in E-mode (i.e., effectively a capacitively coupled plasma), distinctly showing two independent plasmas in the low pressure region.…”

Spatiotemporal optical structure of plasmas in the E-to-H mode transition in an inductively coupled plasma in Ar

“…In an inductively coupled plasma (ICP), it is well known that there are two different modes, E and H, and that the mode transition is a function of the external plasma parameters [5][6][7][8][9][10]. In our previous work, we studied the two-or three-dimensional (2D or 3D) profile of the net excitation rate of each of these modes from optical computerized tomography (CT) images in an ICP source, sustained in a quartz chamber with a diameter of 10 cm and a length of 20 cm driven by an external singleturn current coil at 13.56 MHz, located at the center of the cylinder [11][12][13][14][15]. CT images showed that the axiasymmetrical profile in E-mode is quite different from that of symmetry in H-mode [13,14].…”

Space-and Time-Resolved E–H Transition in an Inductively Coupled Plasma in Ar

“…The details of the E-H transition are not well understood, whereas it is well known that there is a mode transition between the E-and H-modes. In our previous study, we investigated 3-D emission images of both modes of ICP by computerized tomography in Ar and H 2 , respectively [1], [2]. The dynamics of E-H transition in atmospheric Ar ICP are investigated [3].…”