A new crystal growth technique named Induction heating and thermal field up-shift method (ITUM) has been developed in our laboratory. In this method a molybdenum crucible is directly induced by RF generator in hydrogen atmosphere for melting the material inside and then the RF coil is moved upward while the crucible is kept at rest, so that the solid-liquid interface will move from the bottom to the top of the crucible to accomplish the crystallization process.
介绍了一种新的温度梯度法晶体生长技术,称为“感应加热温场上移法”(induction heatingand thermal field up-shift method,ITUM),该法是用钼坩埚在氢气气氛下直接感应加热,使其中的原料熔化。 保持坩埚不动,通过线圈的上移,实现熔体的凝固结晶。
By comparisons of the radial temperature gradients of crystal growth surfaces under the conditions of diverse coupling clearances and locations of RF coil, it can be concluded that induction heating efficiency can be improved by reducing the space between the turns of coil, while the radial temperature gradient of growth surface would also be increased, which can aggrandize the thermal stress inducing the structure defects such as micropiple and dislocation in the crystal.
The RF electromagnetic field is calculated by solving Maxwell's equations expressed in terms of the vector potential, which permits great flexibility in the specification of the RF coil design.
Further experiments are suggested, including details of an improved rf coil design, which should lead to information about the quasiparticle interaction.
A new crystal growth technique named Induction heating and thermal field up-shift method (ITUM) has been developed in our laboratory. In this method a molybdenum crucible is directly induced by RF generator in hydrogen atmosphere for melting the material inside and then the RF coil is moved upward while the crucible is kept at rest, so that the solid-liquid interface will move from the bottom to the top of the crucible to accomplish the crystallization process. Titanium doped sapphire lase...
介绍了一种新的温度梯度法晶体生长技术,称为“感应加热温场上移法”(induction heatingand thermal field up-shift method,ITUM),该法是用钼坩埚在氢气气氛下直接感应加热,使其中的原料熔化。保持坩埚不动,通过线圈的上移,实现熔体的凝固结晶。已用这种方法成功地长出光学质量良好的掺钛氧化铝可调谐激光晶体。本文介绍这种方法的工艺装置和生长过程,给出初步的激光实验和晶体质量的检测数据:对于从熔体中生长高温晶体具有重要的意义。
MR imaging quanlity is affected by many parameter adjustment factors, such as RF coil(Tune), Resonance, Shim, Pulse Offset, Pulse Gain and Quadrature Symmetry and so on. These all are analysed on TOMIKON BMT1100 MR Scanner in this paper.
We have developed an NMR micro imaging system in our laboratory. It features low cost, high performance, simple and convenient operation, as well as easy maintenance. This system may be divided into two parts. The hardware part mainly includes a Selective Excitation Unit (SEU), three channels of Pulse Gradient field Unit and two micro imaging probes with RF coil diameters of 5mm and 25mm, respectively. Whereas the software, integrating with real time control and waveform generation, was imple...