冷凍真空幫浦抽氣性能及再生程序研究

Pumping Performance and Regeneration Procedure of Cryopump

沈一宏(Yi-Hung Shen)

指導教授 ： 鄭鴻斌

國立臺北科技大學/機電學院/冷凍空調工程系所/碩士(2006年)

摘要

在真空製程設備當中，真空幫浦是真空腔體保持真空環境的動力。而冷凍真空幫浦（Cryopump）利用極低溫環境來吸附真空腔體內的氣體以達到抽氣效果，抽氣機制包含低溫冷凝、低溫吸附及低溫捕獲等三種方式，冷凍系統採用以氦氣作冷媒的閉迴路二級Gifford-McMahon (G-M)冷凍機，其型式為ULVAC-10PU，幫浦內部的溫度分別為10~20 K及50~80 K二部分。且由於冷凍真空幫浦大量應用於高科技行業的昂貴高潔淨高真空製程設備當中，因此性能及技術的發展也就大大的影響了這些真空製程設備的性能及相關產業的製程與生產流程。本論文依據國際測試規範建置冷凍真空幫浦性能量測系統及所建議的實施步驟，進行冷凍真空幫浦受熱時抽氣速率及再生程序研究。以將加熱器直接置放於冷凍真空幫浦內部第二級冷凝面的頂端與置放石英燈加熱器於冷凍真空幫浦所連接的測試腔體頂部正中央兩種方法探討將熱量傳遞至冷凍真空幫浦內部後對幫浦的抽氣性能研究。結果發現當加熱器功率為15W且分別通入氮氣與氬氣時，抽氣速率明顯下降，其範圍分別介於367.4~1,001.1 liter/sec及380~934 liter/sec。而另一石英燈加熱器所通入的最大功率為20W，結果發現隨著增加石英燈加熱燈的功率，冷凍真空幫浦的抽氣性能變差，但是仍然可以正常運作。其範圍分別介於1,470~2,492 liter/sec及1,393~2,469 liter/sec。而在再生程序中則以搭配使用不同內、外部熱源及氮氣掃氣進行再生，探討冷凍真空幫浦再生後的再生效果。結果發現在再生程序中使用內部第二級冷凝面頂部的加熱器但不使用氮氣掃氣時能擁有94％的再生效果且又能同時擁有最節省支出成本及總再生程序時間。

關鍵字

冷凍真空幫浦 ； 超低溫 ； 冷凝面溫度 ； 抽氣速率 ； 抽氣容量 ； 再生程序

並列摘要

Among the vacuum equipment, vacuum pump is the power to maintain vacuum environment in the vacuum cavity. Cryopump uses a cryogenic environment to adsorb the gas inside a vacuum chamber for pumping effect. The pumping mechanism includes cryocondensation, cryosorption, and cryotrapping. Refrigeration system uses two-stage Gifford-McMahon (G-M) closed-loop gaseous helium cryopump; the model was ULVAC-10PU and the temperature inside the cryopump is 10-20K and 50-80K. Since cryopump is widely applied to expensive vacuum equipment in high-tech industry, thus, the functions and technologies of the cryopump would affect the performance of the vacuum equipment significantly, as well as the production process of related industries. This study established cyropump capacity measurement system in accordance to the international test standard and suggested procedures, and conducted tests on pumping speed and regeneration procedures on cryopump when heated. The test methods included placing the heater directly on the top of the second-stage surface inside the cryopump, and placing the quartz heater at the center top of the test cavity connected to the cryopump, and both were tested for effect of the transmission of heat to the inside of cryopump on pumping performance. The results showed that when the heater power was 15W, and nitrogen and argon were inputted respectively, the pumping speed decreased significantly, at range of 367.4~1,001.1 liter/sec and 380~934 liter/sec. The maximum throughput of quartz heater was 20W. As the quartz heater power increased, the pumping speed of the cryopump decreased, but the cryopump was able to function normally. The range was 1,470~2,492 liter/sec and 1,393~2,469 liter/sec. In the regeneration process, different internal and external heat sources and nitrogen scavenging were used for regeneration, in order to discuss the regenerating effect of cryopump after regeneration. The results showed that using heater on the top of the second-stage but without nitrogen scavenging could produce 94% regenerating effect, and have the lowest cost and shortest regeneration time.

並列關鍵字

cryopump ； cryogenic ； cryopanel temperature ； pumping speed ； pumping capacity ； regeneration procedure

參考文獻

[4]. M. M. Menon, G. J. Laughon, R. Maingi, M. R. Wade, D. L. Hillis, N. A. Mahdavi, 1995, “Pumping characteristics of a cryopump with Ar sorbent in the He and in a D2/He Mixture”, Journal of Vacuum Science & Technology. A13(3), pp551-555.

[5]. N. Gotoh, T. Momose, H. Ishimaru, M. P. Larin, 1995, “Liquid helium cryopumps with low-emissivity Al film coatings and low helium consumption” Journal of Vacuum Science & Technology. A13(5), pp2579-2581.

[6]. U. Timm, H. H. Klein, S. Schreck, H. U. Hafner, M. M. Klosson, H. J. Mundinger, 1995, ”Refrigerator cryopump with a simple oil-free roughing pump”, Vacuum, pp879-881.

[7]. Y. Shiokawa, T. Kikuch, M. Ichikawa, 1996, “Development of XHV, vibration-free cryopump”, Vacuum, pp803-805.

[8]. Y. Iwasa, S. Ito, 1996, “A new type of cryopump with a metal cryopanel cooled below 3.6K by a two-stage GM refrigerator”, Vacuum, pp675-678.