Characterization of a hybrid plasma and its application to a chemical synthesis

Abstract

A numerical model has been developed for predicting the two-dimensional flow and temperature fields in a hybrid plasma which is characterized by the superposition of an rf plasma and an arc jet. Calculations have been made for the confirmation of a prominent feature of the hybrid plasma. As might be expected, the derived results suggested that the hybrid plasma has a possibility to offer higher efficiencies for practical processing than other conventional plasmas. Particularly noteworthy is the disappearance of a recirculation eddy found in a usual rf plasma, by the presence of the high velocity and high-temperature channel caused by an arc jet flow. Moreover, the relative insensitive character of the exit gas enthalpy to the rf input power was found. Based on the theoretical investigations, a reactor was designed to confirm the effectiveness of the hybrid plasma for chemical syntheses. Using the reactor, ultrafine amorphous Si3N4 with the nitrogen content of 37±0.5 wt. % and the size of 10–30 nm, which can meet the purity and size requirements of an ideal Si3N4 powder, could be prepared successfully by a reaction of SiCl4 and NH3. These theoretical and experimental investigations confirmed that the hybrid plasma torch is an effective reactor for the preparation of ultrafine refractory compounds by plasma chemical vapor deposition (CVD) processes.

Ultrafast thermal plasma physical vapor deposition of thick SiC films

“…The deposition of SiC films was performed in a hybrid plasma processing system, which has been previously described in detail [9,13,14]. In order to investigate the effect of the plasma velocity and the energy density, two kinds of torch were used, namely, with and without a nozzle.…”

Efficient Radio Frequency Inductive Discharges in Near Atmospheric Pressure Using Immittance Conversion Topology

“…But, since the internal resistance of the rf coil will automatically be included with the plasma resistance, we will here, therefore, discuss the influence of internal resistance of the primary Fig. 7 Evaluation of the immittance circuit properties using equation (13). Comparison between circuit calculation and experimental results.…”

“…And because of high-efficiency and highpower operation, high-power semiconductor devices, such as static induction transistor (SIT) inverter power source has become popular in the last decade due to their applications to various kinds of induction heating and plasma generation [12][13][14][15][16][17][18]. But, at high operating frequencies in the MHz range, rf system shows transient and strongly dynamic behavior due to the presence of reactive components in the power source [19], and non-linear coupling and dynamic interaction between the plasma and the rf source [20,21].…”

Advancement of Powder Spheroidization Process Using a Small Power DC-RF Hybrid Plasma Flow System by Sinusoidal Gas Injection

“…On the other hand, RF-ICP flow also has advantages, such as large plasma volume and long residence time of in-flight particles. RF-ICP flow, however, has disadvantages such as flow instability by strong back flow induced by Lorentz force in an RF coil region (5) . Therefore, a DC-RF hybrid plasma flow system, which is the RF-ICP flow assisted by the low power DC plasma jet, is expected to overcome such individual disadvantages of the conventional plasma flow generation systems.…”