A4.3 - Modular Phased Array Ultrasound Doppler Platform for Measurements in Liquid Metals

AMA Conferences 2015
2015-05-19 - 2015-05-21
Nürnberg, Germany
Proceedings SENSOR 2015
A4 - Ultrasound II
H. Beyer, R. Nauber, N. Thieme, L. Büttner, J. Czarske - Technische Universität Dresden (Germany)
104 - 107


The quality of silicon ingots for photovoltaics can be improved by applying time-varying magnetic fields during the solidification process. Their influence on the material and heat transfer in the molten silicon is investigated by means of numerical simulation and laboratory-scale model-experiments with lowmelting metals. Ultrasound Doppler velocimetry is suitable for flow investigations of opaque liquids. While conventional systems using transducers with fixed sound field provide only limited resolution, our approach is to use a phased array (PA) with the ability to focus and steer its acoustic field. We present a phased array ultrasound Doppler velocimeter (PAUDV) for flow mapping and novel measurement methods like two-point correlation of turbulent flows. The PAUDV is a modular platform with 256 independent controllable channels. Each channel is capable of transmitting pulse bursts with a peak-to-peak amplitude of 200 V, a frequency typically ranging between 1 and 10 MHz and a burst length of one to sixteen periods. The bursts across all channels can be aligned and delayed with a resolution of 1.6 ns to each other with a maximum repition frequency of approx. 60 kHz. The PAUDV is a modular system consisting of two backplanes, one master card (control module) and up to eight transceiver cards with 32 channels each. A measurement example of the sound field from a designed phased array is given, which shows that the achievable lateral resolution is better than 1.5 mm for that system configuration.