Polypropylene and nylon 66 fabrics are subjected to atmospheric pressure He and He-O 2 plasmas for selected exposure time intervals. Scanning electron microscopy analysis of the fabrics shows no apparent changes in the plasma-treated nylon fiber surfaces, but significant surface morphological changes for the polypropylene. Surface analyses of the nylon filaments reveal small differences in the surface carbon and oxygen contents between the treated and control groups. The surface oxygen and nitrogen content of the polypropylene fabric increases significantly after treatment in both He and He-O 2 plasmas. There is a slight decrease in nylon fabric tensile strength after treatment in He plasma for 3 minutes, while. there is no significant change in tensile strength of the nylon fabric treated with He-O 2 after exposure times of up to 8 minutes.Plasma treatment of textile fabrics and yams is being investigated as an alternative to wet-chemical fabric treatment and pretreatment processes, e.g., shrink resistant (wool) or water-repellent finishing, which tend to alter fabric mechanical properties and are environmentally hazardous. Plasma treatment of textiles may result in desirable surface modifications, including but not limited to surface etching, surface activation. crosslinking, chain scission, decrystallization, and oxidation. Treatment depends on the choice of working gas and plasma density and energy [ 1,3,6,14,17,19]. The effects of low-pressure (vacuum) plasma treatments of polyester, high performance polymers, and wool are well documented [3, 11, 17, 191, while relatively little has been published about atmospheric pressure plasma treatments [4, 14, 171. Despite the effectiveness of plasma treatments on textiles, the inability to successfully incorporate low-pressure plasma treatment equipment into a continuous textile finishing operation has seriously limited the commercial viability of the technique [ 11 ]. Previously, plasmas generated at atmospheric pressure were believed to be neither uniform nor stable: however, recent research on atmospheric plasmas has shown their uniformity, stability, and applicability to processing and treatment of textiles, as well as many other materials [2]. In addition, atmospheric pressure plasma treatment devices can be integrated with continuous on-line processing of textile materials.While plasma treatment may result in many favorable or desirable surface modifications of textile materials. it may also cause undesirable physical degradation of the polymer surface [5,10,11 ]. Treatment parameters must be optimized in order to achieve desirable surface modifications without changing bulk properties. This paper presents results on polypropylene and nylon 66 fabrics treated with atmospheric plasmas of helium (He) and a mixture of helium and oxygen (He-02). Helium is typically used to initiate and generate the plasma at atmospheric pressure before another gas is introduced to the system. If there are no measurable changes in surface or mechanical properties as a result of e...

A bstrocf-Measurements of the visible light obtaining quantitative data difficult. In this paper, we discuss emission from dense, weakly non-ideal Plasmas efforts to measure the average plasma temperature by using have been Performed On the the relative line ratio method. The results using this electrothermal launcher device "SIRENS". The technique are with the results o~conduc~vity, h a plasma is created by the ablation of a Lexan insulator in the source, which then flows through a flux, and mass loss methods for deducing temperature. cylindrical barrel which serves as the material sample. Visible light emission spectra have been observed both in-bore and from the muzzle flash of the barrel, and from the flash of the source.Due to high plasma opacity (the plasma emits as a near blackbody) and absorption by the molecular components of the vapor shield, the hotter core of the arc has been difficult to observe. Recent measurements along the axis of the device indicate time-averaged plasma temperatures in the barrel of about 1 eV for lower energy shots, which agree with experimental measurements of the average heat flux and plasma conductivity along the barrel. Measurements of visible emission from the source indicate time averaged temperatures of 1 to 2 eV which agree with the theoretical estimates derived from ablated mass measurements and calculated estimates derived from plasma conductivity measurements.

Optical spectroscopic analyses have been performed to study luminescence from plasmas produced by ablation of YBa2Cu3O7 single-phase high Tc bulk superconductors exposed to XeCl excimer laser (308 nm) pulses. Only excited atomic neutral and single ionized species (Cu/Cu+, Ba/Ba+, Y/Y+) were observed within the experimental resolution of an optical multichannel analyzer detection system, when irradiating the targets in vacuum (∼10−5–10−4 Torr). Conspicuously absent in the spectra (300–800 nm range) are molecular emission bands that would appear if large excited molecules or fragments were present. Implications of the present results are discussed which relate to an early hypothesis about the laser ablation mechanism and their influence on high Tc film characteristics.

In order to understand the relationships between confinement and space potential (electric field) and between confinement and density fluctuations, plasma parameters in the ELMO Bumpy Torus Scale (EBT-S)[in Plasma Physics and Controlled Nuclear Fusion Research (IAEA, Tokyo, 1974), Vol. 2, p. 141; Plasma Phys. 25, 597 (1983)] have been measured systematically for a wide range of operating conditions. Present EBT plasma parameters do not show a strong dependence on the potential profile, but rather exhibit a correlation with the fluctuations. The plasma pressure profile is found to be consistent with the profile anticipated on the basis of the flute stability criterion for a marginally stable plasma. For a heating power of 100 kW, the stored energy density is found to be restricted to the range between 4.5×1013 eV-cm−3 and 7×1013 eV-cm−3. The lower limit remains constant regardless of heating power and pertains to plasmas lacking an equilibrium and/or stability. The upper limit increases with heating power and is found to result from the onset of instabilities. In between the two limits is a plasma that is in an equilibrium state and is marginally stable. Operational trajectories exist that take the EBT plasma from one limit to the other.

The results of a significantly more efficient model (molecular model) for computing particle and energy sources from recycling in edge plasma transport codes, such as b2, are compared with results from more detailed calculations using the b2 code coupled with the neutral transport code, DEGAS. The molecular model considers the reflux both of cold molecules and of energetic backscattered atomic neutrals from the divertor target plates and has been implemented to function intemally within the b2 code. The molecular model calculations are shown to be in reasonable agreement with more detailed calculations done with the coupled b2/DEGAS codes for seven cases typical of conditions in the scrape-off layer of the Doublet III (DIII-D) tokamak. Because the molecular model is a far less expensive computational tool, it represents a significant improvement over the existing (coupled) edge transport recycling model. Thus, it may find wider application in design studies for future devices, such as the International Thermonuclear Experimental Reactor (ITER).