Trench MOS-gated power devices

MOS gated power devices are now available for power switching applications with voltage blocking requirements up to 1 kV and current ratings up to 300A. This is due to the invention of the IGBT, a device in which MOS gate turn-on leads to minority carrier injection to modulate the high resistance drift region required for voltage blocking. The paper presents current technologies being developed in order to expand the applications of MOS gated power devices. Also explained is the available trench gate technology that can be used to fabricate power devices.

Long-range interactions in turbulence and the energy decay problem.

We discuss the long-range interactions that arise in homogeneous turbulence as a consequence of the Biot-Savart law. We note that, somewhat surprisingly, these long-range correlations are very weak in decaying, isotropic turbulence, and we argue that this should also be true for magnetohydrodynamic, rotating and stratified turbulence. If this is indeed the case, it is possible to make explicit predictions for the rate of decay of energy in these anisotropic systems, and it turns out that these predictions are consistent with the available numerical and experimental evidence.