Large-scale vortical structure detection using microphone array in a semiconductor single wafer spin cleaner

Fluctuating pressure (p’ ) of a large-scale vortical structure generated in a semiconductor single wafer spin cleaner was detected by using microphone array. Twelve microphones were installed on the exhaust cover under the rotating disk of the cleaner with their interval of 7.5° or 15°. Power spectrum densities (PSD) of p’ were compared with those of fluctuating velocity measured by PIV for various rotation angular velocities to identify fluctuations due to convection of the large-scale vortical structure. Good agreement of PSDs indicates that the large-scale structure could be detected by using microphone. Cross-correlation of p’ measured at different positions revealed that the large-scale structure convected to the downstream in the rotational direction of the disk. The convection speed was about 12 % of the angular velocity of the rotating disk. Number of the vortex in the large-scale structure was also evaluated from the time-series p’ data. Time-space contour map was made for p’ based on the data measured at the different angular position, and showed periodical swept strip patterns. Presences of the strip patterns indicate the pressure disturbances were stably convected to the downstream. From this time-space map, two-dimensional Fourier transform efficiently extracted the number of vortices in the large-scale structure

Periodical structure of vortices in a semiconductor single wafer spin cleaner

We experimentally and numerically investigated large-scale structures formed by vortices in a single wafer spin cleaner. The Q-criterion identified the vortices developed in the cleaner as the flow regions with positive second invariant of the velocity gradient tensor obtained by both the PIV and LES. The time-series two-components PIV data shows that small-vortices were clustered near and under the edge of the rotating disk and were periodically emanated from there to the housing wall of the cleaner. The emanation frequency was increased with increasing in the angular velocity of the rotating disk. Three-dimensional LES reveal that six longitudinal vortices were spirally developed from under the edge of the rotating disk to the housing wall. This structure stably rotated slower than the disk speed. Fourier analysis of the LES data agreed with that of the PIV data. This supports that the passages of the stable spiral vortices on the PIV measurement region resulted in the periodical emanation of the clustered small-vortices observed in the PIV. Such a very large-scale spiral structure will induce reattachment of contaminants on the wafer surface, and should be destructed for development of much higher efficient cleaner

A case of primary racemose hemangioma with endobronchial lesions demonstrating recurrent hemoptysis initially treated with bronchial arterial embolization

Primary racemose hemangioma of the bronchial artery (RHBA) is one of the causes of massive hemoptysis. A 72-year-old woman was admitted to our hospital with recurrent hemoptysis. Bronchoscopy showed an endobronchial lesion, and the angiography of the right bronchial arteries indicated RHBA. Bronchial arterial embolization (BAE) was performed to prevent hemoptysis. Although the endobronchial lesion shrank after the first BAE, the lesion re-increased and caused massive hemoptysis. A thoracoscopic right upper lobectomy was performed, and hemoptysis did not recur. Therefore, in cases of RHBA where there is recurrent hemoptysis and the endobronchial lesions that remain after BAE, additional treatments should be considered