Directional power absorption in helicon plasma sources excited by a half-helix antenna

This paper deals with the investigation of the power absorption in helicon plasma excited through a half-helix antenna driven at 13.56 MHz. The simulations were carried out by means of a code,HELIC. They were carried out by taking into account different inhomogeneous radial density profiles and for a wide range of plasma densities, from 10^（11） cm^（-3） to 10^（13） cm^（-3）. The magnetic field was 200, 400, 600 and 1000 G. A three-parameter function was used for generating various density profiles with different volume gradients, edge gradients and density widths. The density profile had a large effect on the efficient Trivelpiece–Gould（TG） and helicon mode excitation and antenna coupling to the plasma. The fraction of power deposition via the TG mode was extremely dependent on the plasma density near the plasma boundary. Interestingly, the obtained efficient parallel helicon wavelength was close to the anticipated value for Gaussian radial density profile.Power deposition was considerably asymmetric when the n/B_0 ratio was more than a specific value for a determined density width. The longitudinal power absorption was symmetric at approximately n_0 =10^（11） cm^（-3）, irrespective of the magnetic field supposed. The asymmetry became more pronounced when the plasma density was 10^（12） cm^（-3）. The ratio of density width to the magnetic field was an important parameter in the power coupling. At high magnetic fields, the maximum of the power absorption was reached at higher plasma density widths. There was at least one combination of the plasma density, magnetic field and density width for which the RF power deposition at both side of the tube reached its maximum value.

Effects of wet feeding and early feed restriction on blood parameters and growth performance of broiler chickens

The aim of the study was to investigate the effects of early feed restriction(FR) with wet feeding on size of small intestine, blood lipids and performance parameters in broilers from d 1 to 42. A total of 160 oneday-old male broiler chickens were randomly allocated to 4 treatments with 4 pens per treatment and 10 chickens per pen, in a fully randomized 2×2 factorial arrangement, two feeding arrangement; providing feed ad libitum(Full Fed) or FR by 50% between days 6 to 12, and feed in either wet or dry form(wet form, 1.2 g water per 1 g dry feed). Body weight and feed intake of broiler chickens were determined at d 0, 21, and 42, and feed conversion ratio(FCR) was calculated. At d 42, two birds per replicate were euthanised for determination of carcass weight, organ weight and length, and also for blood parameters,which included high density lipoprotein(HDL), low density lipoprotein(LDL), total cholesterol and triglycerides(TG). The broilers fed wet form irrespective of FR throughout had superior body weight gain and carcass weight compared with birds fed dry diets at d 22 and 42(P < 0.05). The wet form with FR significantly showed lower FCR compared with the wet form and ad libitum at d 1 to 21(P < 0.05). The broilers fed wet form had significantly increased HDL, LDL, and total cholesterol and decreased TG(P < 0.05). In conclusion, wet form can improve performance growth and blood parameters, and the FR birds were able to attain normal market body weight at d 42, which suggests that growth compensation occurred.