Unstable plasma characteristics in mirror field electron cyclotron resonance microwave ion source

Electron cyclotron plasma reactor are prone to instabilities in specific input power [3–7] region (150–450 watts). In this region power absorption by gas molecules in the cavity is very poor and enhanced input power gets reflected substantially without increasing ion density. There are abrupt changes in plasma characteristics when input power was decreased from maximum to minimum, it was observed that reflected power changed from <2% to ∼50%. Minimum two jumps in reflected power were noticed in this specific power region and these appear to be highly sensitive to three stub tuner position in the waveguide for this particular input power zone. Unstable plasma region of this source is found to be dependent upon the magnetic field strength. Some changes in reflected power are also noticed with pressure, flow and bias and they are random in nature.     

Geometry effect on the nonlinear magnetic response of YBa2Cu3O7−y

Results are presented for study of nonlinear magnetization of a sintered YBa₂Cu₃O_7−y pellet of different thickness of a sample subjected to very low magnetic field. On cooling the sample belowT _c in zero field a change, in the oscillatory structure of harmonics in increasing dc field is observed in very low ac magnetic field. The effect of finiteness of the sample on the oscillatory structure and on the hysteresis of harmonics is also studied. The results are explained qualitatively.     

Lipase-Catalyzed Solvent-Free Amidation of Phenolic Acids

A series of N-alkyl-substituted amides, based on various phenolic acids, have been synthesized by the condensation of equimolar amounts of phenolic acids with different alkyl amines in the presence of Candida antarctica lipase at 60–90 °C in 16–20 h. The reactions were carried out in a solvent-free system without the use of any activating agents. All the products were obtained in appreciable amounts and the yields for different compounds varied between 75.6% and 83.5%. The synthesized compounds were characterized using spectroscopy techniques, namely infrared and NMR (¹H and ¹³C).