Experimental study of CF4 conical theta pinch plasmaexpanding into vacuum

Langmuir probe, photodiode, and optical multichannel analyzer (OMA) measurements have been made on a pulsed CF₄ conical theta-pinch plasma. A cloud of CF₄ was puffed into a conical theta-pinch coil, converted to plasma, and propelled into the vacuum region ahead of the expanding gas cloud. At a position 67 cm away from the conical theta-pinch coil, the plasma arrived in separate packets that were about 20 μs in duration. The average drift velocity of these packets corresponded to an energy of about 3 eV. The OMA measurements showed that the second packet contained neutral atomic fluorine as well as charged particles. The electron temperature and ion density in the second packet were 2.0 eV and 1.5×10¹³ cm^-3, respectively. The electron temperature and ion density in the wake plasma were 8.3 eV and 4×10¹¹ cm^-3 , respectively. This device can be used for plasma processing or as a laboratory test of numerical and analytical models of the expansion of plasma into vacuum     

Mass transport characteristics in a pulsed plasma enhanced chemicalvapor deposition reactor for thin polymer film deposition

A pulsed plasma enhanced chemical vapor deposition (PECVD) reactor is used for the preparation of thin polyacetylene films. A theoretical model based on the mass transport characteristics of the reactor is developed in order to correlate with experimentally obtained spatial deposition profiles for the acetylene plasma polymer film deposited within the cylindrical reactor. Utilizing a free radical mechanism with gas phase initiation of the polymerization reaction as the rate controlling step, a system parametric study is performed to predict the Peclet number range of operation for the pulsed PECVD reactor. This parametric study indicates radical decay by diffusion to the reactor walls to be the significant physical phenomenon in the system. It is concluded that a quasi-steady-state model is a good tool for predicting the important mass transfer phenomena occurring in the pulsed plasma reactor     

Deposition of plasma-polymerized acetylene by an intense pulsed RFplasma source

An inductively coupled, intense, pulsed RF plasma source deposited plasma-polymerized acetylene at a rate of 127 Å per discharge. The potassium bromide substrate was located 18-cm downstream from the RF coil. A puff valve admitted parent acetylene gas just before the transient RF current was applied. Fourier transform infrared (FTIR) spectra showed that carbon-to-carbon double bonds were formed. Scanning-electron-microscope images showed that the film thickness after 79 discharges was 1 μm. A photodiode showed substantial light emission for about 30 μs during each discharge     

Explosion model applied to an intense pulsed plasma source for thinfilm deposition

A pulsed plasma source for deposition of thin polymer films was modeled numerically with the one-dimensional (1-D) time dependent fluid transport equations describing an explosion for an ideal gas. Initial number density, explosion temperature, and velocity were made consistent with values in an experimental reactor. These quantities as well as pressure and fluence were modeled for a distance of 2 m and for a time duration of 93 μs. The trajectory for maximum pressure calculated from the model was observed to be consistent with the experimentally measured trajectory of maximum emitted light from an acetylene plasma. Measured axial profiles of areal density for the deposited polymer films were compared with modeled fluence