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Deals with a study which verified the smooth-approximation theory for a space-charge dominated beam in an axisymmetric periodic focusing channel. Review of the smooth-approximation theory for an axisymmetric focusing channel; Analysis of the image signals; Significance of the spherical aberration effect in solenoidal focusing system.

Fe3O4 thin films with a thickness of about 140 nm have been deposited on MgO (001) substrates by reactive sputtering. Microstructural studies indicated that monocrystalline Fe3O4 thin films were epitaxially grown on the MgO substrates with a cubic-on-cubic orientation relationship with respect to the substrates. Strain field due to slight lattice mismatch between the films and substrates was observed. The saturation moment and the coercivity for in-plane magnetization hysteresis loop were 235 emu/cc and 500 Oe, respectively. The lower saturation moment value of the Fe3O4 thin film suggested that the strain field may play a role in the reduction of magnetization. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Lower hybrid wave (LHW)-plasma coupling experiments in HT-7 [J. K. Xie and HT-7 Group, Proceedings of the 16th International Conference on Fusion Energy, Montreal, 1996 (IAEA, Trieste, 1997), Vol. 1, p. 685] were carried out by means of puffing gas (CD4 and D2) just around the antenna. Both experiments show that wave-plasma coupling is improved by the gas puffing. The maximum distance between the plasma and the antenna is limited to about 8 cm due to the plasma disruption. The variation in the lined averaged density in the different channels gives a possible evidence of the mechanism of the ionization of neutral gas. The effect of the gas flow rate on the wave-plasma coupling shows that an optimized gas flow rate is necessary for good coupling, being consistent with simulation through Brambilla theory qualitatively. Experiments with puffing D2 show that the improved coupling results from the global density increase and the local gas puffing. Langmuir probe measurements indicate that the gas puffing effectively increases the density and decreases the temperature in scrape of layer. Studies show that the ionization of the puffed gas is affected by both LHW electric field and plasma temperature. Comparison of D2 and CD4 puffing shows that D2 improves coupling better with less effect on core density. [ABSTRACT FROM AUTHOR]