کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
7055902 1458046 2016 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Propagation of nitrogen gas in a liquid helium cooled vacuum tube following sudden vacuum loss - Part I: Experimental investigations and analytical modeling
ترجمه فارسی عنوان
انتشار گاز نیتروژن در یک لوله خلاء خنک کننده هلیوم پس از ناخواسته از دست دادن خلاء - قسمت اول: تحقیقات تجربی و مدل سازی تحلیلی
کلمات کلیدی
از دست دادن خلاء تصادفی، سرعت انتشار، ابررسانایی، شتاب دهنده ذرات، پرتو خط،
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی جریان سیال و فرایندهای انتقال
چکیده انگلیسی
This paper describes propagation of near atmospheric nitrogen gas that rushes into a liquid helium (LHe) cooled vacuum tube after the tube suddenly loses vacuum. The loss-of-vacuum scenario resembles accidental venting of atmospheric air to the beam-line of a superconducting particle accelerator and is investigated to understand how the in-flowing air will propagate in such geometry. In controlled experiments, we simulated loss of vacuum by rapidly venting a large reservoir of nitrogen gas (a substitute for air) to a vacuum tube immersed in a LHe bath at 4.2 K. The resulting rise in the tube pressure and temperature were measured by pressure probes and thermometers arranged along the tube length. The data show that the propagation of nitrogen gas in the LHe cooled vacuum tube is orders of magnitude slower than in the same tube at room temperature. Interestingly, the gas front speed in the LHe cooled tube also decreases along the tube. A gas propagation model developed by employing conservation of mass identifies mass transfer (gas condensation in the tube) as the principal cause of the slow propagation as well as of the front deceleration. Some limitations of this analytical model are discussed in the context of quantifying the propagation speed. The speed obtained from direct measurements is seen to decrease exponentially along the tube. This exponential decay form of the propagation speed well represents the data from experiments that have different mass flow rates of nitrogen gas flowing into the vacuum tube after venting.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: International Journal of Heat and Mass Transfer - Volume 96, May 2016, Pages 573-581
نویسندگان
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