射頻共振空腔推進器

NASA鷹工廠(Eagleworks Laboratories)所建造的射頻共振空腔推進器原型機

射頻共振空腔推進器(英語:RF resonant cavity thruster),或稱相對性推進器,是一種尚具爭議性的新型態推進裝置,最常見的稱呼為「電磁推進器」(EmDrive、電磁驅動引擎),由英國航空太空工程師羅傑·肖耶(Roger Shawyer)發明,他在2000年創建Satellite Propulsion Research[1][2] 。這種技術可以用來促進交通工具革命,包括地面交通,海洋交通,航空太空載具[3][4][5][6][7][8]

至2016年底,相對性推進器研究已經逐漸進入主流科學界實驗如NASA,但批評家認為相對性推進器違反動量守恆。一些科學家及美國太空總署林顿·约翰逊太空中心鷹工廠(Eagleworks)實驗室,德國德勒斯登工業大學、西北工業大學已經完成原型設計。目前有一些實驗觀察到相對性推進器產生小型推力,但也受到其他科學家懷疑。之後對於相對性推進器的研究仍進行中,至今從未獲得令人信服的物理原理或實驗結果。

概念主張

科學家羅傑·肖耶提出在椎體內發射微波,微波在密閉空間內反復地反彈,進而產生的輻射壓推動椎體前進。

射頻共振空腔推進器原理有幾種可能:

  • 量子真空憑空產生的虛粒子推動射頻共振空腔推進器
  • 通過改變射頻共振空腔推進器前後的時空來產生推進力
  • 微波存在更高維度,射頻共振空腔推進器內部在高維空間前進
  • 馬赫效應(Mach effect):詹姆斯·伍德瓦德於1990年提出,即在加速物體所受的力中,有一部分力不會產生動能,而是轉化為勢能儲存在物體中,使物體的靜止質量出現波動,從而產生實驗中觀察到的推力。

研究發展

英國航空太空工程師羅傑·肖耶在2000年創建Satellite Propulsion Research,致力於相對性推進器研究。肖耶在2003年進行實驗,並稱相對性推進器實驗產生16毫牛頓推進力。[9]

2006年,美國工程師吉多·費塔(Guido Fetta)仿照EmDrive製作出一台原型機「Cannae Drive」。同年9月8日,英國科學雜誌新科學人》以EmDrive為封面[10],發表文章認為該裝置似乎是可信的。科幻作家格雷格·伊根公開表示該文章「一味追求轟動效應,作者缺乏基本的科學知識」。格雷格·伊根的文章被美國數學物理學家約翰·拜艾茲轉發在自己的部落格[11][12]。之後《新科學人》迅速發表澄清聲明,並附上專家們對EmDrive持否定意見的公開信。

質疑觀點

無法證實

2010年,中國西北工業大學楊涓教授帶領的團隊開始相對性推進器設計。2013年,楊涓製作出EmDrive原型機,並發表公布測試結果:2.5千瓦電量產生720毫牛頓推進力,實驗記錄比肖耶更好,達到更高功率[8][13]。楊涓注意到此結果得出的推力比同類實驗大百倍,因此表示在作出更多實驗前不會評論這個實驗,並期望其他團隊作重複其實驗引證,她在接著的一次同樣的實驗中不能重複之前的結果,因此認為之前的實驗有錯誤。[14]

2013年8月,美國太空總署在德州林頓·詹森太空中心對兩台Cannae Drive進行為期8天的實驗,並於2014年6月4日將實驗結果在美国航空航天学会(AIAA)第50屆聯合推進大會上發表。實驗數據顯示,28瓦的電力產生30至50微牛頓的推力。2014年10月,肖耶在多倫多航太會議上演講並發表論文。2015年根據英國《每日郵報》報導,美國太空總署工程師鮑爾·馬爾希(Paul March)表示在高度真空中,以一輸入功率50W的相對性推進器產生50μN的推力, torr and new null-thrust tests.[15]馬爾希解釋相對性推進器機制不是洛伦兹力熱力學。但當試圖以反向測試驗證時,其中一實驗設備(120W RF 放大器)燒毀了,因為未能完成測試及得出實驗報告。[16]

2015年7月,德國德勒斯登工業大學馬丁·塔吉瑪教授(Martin Tajmar)在美國航空航太學會推進和能源論壇展示EmDrive更加精密的實驗結果,過程中測得微小的推力,但當把被測試的EmDrive向垂直方向旋轉90°、理論上應無推力的情況下,卻測得相對大得多的推力,意味著實驗中存在著干擾,因此得出無法證實相對性推進器能產生推力。該團隊計劃在更好的磁屏蔽環境下再嘗試。

2016年,中國西北工業大學楊涓的團隊發表文章記述他們進行的另一次實驗,當中使用較精細的設置,包括發射微波的電源在推進器內外兩不同情況。結果電源在外時測得微小推力,但電源在內時卻沒有。因此推斷在外部電源情況測得的推力是噪訊所致。[14]同年11月17日, NASA鷹工廠實驗室的論文《" "Measurement of Impulsive Thrust from a Closed Radio-Frequency Cavity in Vacuum"》 發表在同行評議期刊《推進與動力雜誌》(Journal of Propulsion and Power)上。鷹工廠論文描述對EmDrive進行的測試,測試在接近真空(類似於太空)的環境下進行。他們把引擎放到一個叫做扭擺的裝置上,啟動引擎,然後測量它運行的距離來推算推進力的大小。他們估計,EmDrive消耗每千瓦功率能夠產生1.2毫牛頓的推進力。[17]

反駁結論

2018年,德國德勒斯登工業大學太空工程研究所物理學家馬丁·塔吉瑪領導的團隊發表獨立測試結果,表明推力並非來自 EmDrive,而只是椎室內供電電線與地球磁場的電磁相互作用,因為EmDrive並沒有完全屏蔽地球磁場影響的設備。[18]

參考資料

  1. ^ EmDrive.com. Satellite Propulsion Research Ltd (SPR) web site. Roger Shawyer / SPR Ltd. [2021-08-09]. (原始内容存档于2015-05-06). 
  2. ^ Satellite Propulsion Research. Aerospace Member Directory. ADS Group. [2015-05-02]. (原始内容存档于2014-07-09). 
  3. ^ Hambling, David. Chinese Say They're Building 'Impossible' Space Drive. Wired. Wired. 24 September 2008 [2015-05-02]. (原始内容存档于2015-05-06). 
  4. ^ Hambling, David. Video: 'Impossible' Space Drive In Action?. Wired. Wired. 2 October 2008 [2015-05-02]. (原始内容存档于2015-05-16). 
  5. ^ Hambling, David. 'Impossible' Device Could Propel Flying Cars, Stealth Missiles. WIred. Wired. 29 October 2009 [2015-05-02]. (原始内容存档于2015-05-03). 
  6. ^ Hambling, David. Propellentless Space Propulsion Research Continues. Aviation Week & Space Technology. 5 November 2012 [2015-05-02]. (原始内容存档于2017-01-20). 
  7. ^ Hambling, David. EmDrive: China's radical new space drive. Wired UK. Wired UK. 6 February 2013 [2015-05-02]. (原始内容存档于2015-04-26). 
  8. ^ 8.0 8.1 Hambling, David. Nasa validates 'impossible' space drive. Wired UK. Wired UK. 31 July 2014 [31 July 2014]. (原始内容存档于2014-08-01). 
  9. ^ 10 週就能把人送上火星的 EmDrive 引擎,是偽科學還是世紀大發現?. TechNews 科技新報. [2018-06-15]. (原始内容存档于2020-12-04) (中文(臺灣)). 
  10. ^ Shawyer, Roger. A Theory of Microwave Propulsion for Spacecraft (Theory paper v.9.3) (PDF). New Scientist. September 2006 [2016-09-06]. (原始内容存档 (PDF)于2017-09-07).  参数|magazine=与模板{{cite journal}}不匹配(建议改用{{cite magazine}}|journal=) (帮助)
  11. ^ Egan, Greg. Baez, John C. , 编. A Plea to Save New Scientist. The n-Category Café (a group blog on math, physics and philosophy). 19 September 2006 [2016-09-06]. (原始内容存档于2020-11-09). 
  12. ^ Powell, Corey S. Did NASA Validate an "Impossible" Space Drive? In a Word, No.. Discover. 6 August 2014 [2014-08-06]. (原始内容存档于2014-08-08). 
  13. ^ Brady, David A.; White, Harold G.; March, Paul; Lawrence, James T.; Davies, Franck J. Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum. 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference. American Institute of Aeronautics and Astronautics. 30 July 2014 [31 July 2014]. doi:10.2514/6.2014-4029. (原始内容存档于2015-06-11). 简明摘要 (PDF)NASA (30 July 2014). 
  14. ^ 14.0 14.1 Yang, Juan; Liu, Xian-chuang; Wang, Yu-quan; Tang, Ming-jie; Luo, Li-tao; Jin, Yi-zhou; Ning, Zhong-xi. Thrust Measurement of an Independent Microwave Thruster Propulsion Device with Three-Wire Torsion Pendulum Thrust Measurement System. Journal of Propulsion Technology. February 2016, 37 (2): 362–371 [2016-09-15]. (原始内容存档于2018-01-28) (中文). 
  15. ^ Wang, Brian. Update on EMDrive work at NASA Eagleworks. NextBigFuture. 6 February 2015 [2016-09-15]. (原始内容存档于2016-03-15). 
  16. ^ Wang, Brian. NASA Emdrive experiments have force measurements while the device is in a hard vacuum. NextBigFuture. 7 February 2015 [2016-09-15]. (原始内容存档于2015-02-08). 
  17. ^ NASA Eagleworks. Measurement of Impulsive Thrust from a Closed Radio-Frequency Cavity in Vacuum. AIAA ASSOCIATION. 17 November 2016 [2016-12-02]. (原始内容存档于2020-11-15). 
  18. ^ NASA’s EM-drive is a magnetic WTF-thruster. Ars Technica. [2018-06-15]. (原始内容存档于2021-02-16) (美国英语). 

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