Ahmed M. Hala

Atmospheric Pressure 2.45-GHz Microwave Helium Plasma

A waveguide-based microwave plasma system was built using a resonant cavity and a quartz tube. 2.45 GHz 850 W magnetron was used to obtain helium discharge without an igniter. The temporal images of discharge were recorded on microsecond time scales using an intensified charge-coupled device camera. The excitation temperature was calculated as 3385 K using the helium lines, which were obtained from emission spectrum of the discharge. The gas temperature was measured as 1208 K by a thermocouple.

A Comparison Study of Microwave and Radio Frequency Plasma Polymerized PEDOT Thin Films

PEDOT films were deposited by microwave (MW) and radio frequency (RF) plasma in a medium pressure of 0.02 Torr without precursor. In-situ optical emission spectroscopy (OES) measurement was carried out to determine plasma phase and to adjust discharge parameters. The other spectroscopic methods were used to characterize deposited thin films and to compare the effect of discharge parameters on the process. Conductivity values were found to be around up to 10−5 S/cm for MW plasma, and 10−8 S/cm for RF plasma deposited PEDOT films, without the addition of a doping agent. It was found that both plasma polymerization methods resulted in crosslinked PEDOT structures.

Surface properties of radio frequency plasma treated wool and denim fabrics

Purpose The purpose of this paper was to investigate the effects of hydrochloric acid (HCl), hydrazine, methyl methacrylate, styrene and hexamethyldisiloxane by radio-frequency (rf) plasma graftings on surface properties of wool and denim fabrics. Design/methodology/approach During plasma treatments, processing time was varied under optimized plasma conditions (50 W, rf: 13.56 MHz). All fabrics were comprehensively investigated by means of scanning electron microscopy-energy dispersive X-ray spectroscopy and contact angle measurements. Findings The experimental data shows that the rf-plasma processing has important effect on the wettability properties of wool and denim fabrics. The results indicated that HCl plasma treatment significantly improves the hydrophilicity of wool and denim fabrics. Originality/value The research on wool and denim fabric treatment by plasma is original.

Preliminary Study of a Hybrid Helicon-ECR Plasma Source

A new type of hybrid discharge is experimentally investigated in this work. A helicon source and an electron cyclotron resonance (ECR) source were combined to produce plasma. As a preliminary study of this type of plasma, the optical emission spectroscopy (OES) method was used to obtain values of electron temperature and density under a series of typical conditions. Generally, it was observed that the electron temperature decreases and the electron density increases as the pressure increased. When increasing the applied power at a certain pressure, the average electron density at certain positions in the discharge does not increase significantly possibly due to the high degree of neutral depletion. Electron temperature increased with power in the hybrid mode. Possible mechanisms of these preliminary observations are discussed.

Laser induced fluorescence of argon ion in plasma presheaths

Summary form only given. A tunable diode laser system has been used to measure ion velocity distribution functions of ArII in plasma presheaths using laser-induced fluorescence (LIF). The diode laser system can examine the velocity distribution function with marginally greater resolution than the dye laser owing to their smaller line width (0.001 nm) (Severn et al., 1998). LIF of ArII requires excitation at 668.61 nm. The diode laser is centered at that wavelength with a tuning range of 0.15 nm and the optical amplifier (MOPA) is at 10 nm. LIF measurements of presheaths as a function of pressure (0.5-3 mTorr) were made in a DC hot-filament produced multidipole plasma discharge near a negatively biased plate. The ion velocity has range of 10/sup 3/ cm/s-10/sup 5/ cm/s for presheaths thickness 0.5 cm-5 cm. These measurements are compared with results obtained by using a double sided Langmuir probe (Mach probe) and an emissive probe.