Propellentless Space Propulsion Research Continues

米国の航空宇宙専門誌 Aviation Week '１２.１１.５付けで掲載された記事からだ。

プロペラントレスとは、推進剤が不要な宇宙推進システムということで
言葉からすれば、エネルギー保存則に反しているが・・

欧米が愛想を尽かした EmDrive というアイデアに、中国が注目し
開発を続けていくという内容だ。

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Chinese scientists appear to have validated a　propellentless space propulsion technology previously branded as impossible. Based on earlier British research, it is averred that the EmDrive concept provides sustained thrust at low cost and weight, but this has yet to be accepted even as a workable theory by the wider propulsion community.

The EmDrive story started in 2001 when engineer Roger Shawyer set up Satellite Propulsion Research (SPR) to exploit his new concept in electrical propulsion. He was helped by a modest grant from the U.K.'s now defunct Trade and Industry Department.

（中略）

Shawyer's EmDrive does not have any exhaust. It consists of a tuned cavity shaped like a truncated cone into which resonating microwaves are channeled. Like other radiation, these exert a tiny pressure when reflected off a surface. According to Shawyer, the pressure exerted on the large end of the cavity is greater than the pressure on the small end, producing a net thrust.

This appears to be a violation the law of conservation of momentum. However, Shawyer says net thrust occurs because the microwaves have a group velocity (the velocity of a collection of electromagnetic waves) greater in one direction than the other and relativistic effects to modify the Newtonian mechanics. Shawyer compares the EmDrive to a laser gyroscope, which also looks like a closed system but is actually open and works thanks to relativistic effects.
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EmDriveとされる映像（Aviation Weekより）


テスト風景とされる動画（約１分）

orginal link

それに続く記事には、更に驚くべき内容が・・

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Shawyer built demonstration EmDrives to back his claims, including a 7-lb. version he said produced a thrust of 85 millinewtons (mN) with a 300-watt input. Skeptics, convinced of its impossibility, have not even tested the EmDrive

But the controversy attracted the attention of China's Yang Juan, professor of propulsion theory and engineering of aeronautics and astronautics at the Northwestern Polytechnic University in Xian. Her team set out to explore the EmDrive independently. A 2008 theory paper by Yang and colleagues describes the EmDrive in terms of quantum theory and indicates net thrust is possible. A 2010 follow-up paper calculates a possible thrust of 456 mN from a 1-kw input, and states that the team was getting positive experimental results.

The latest paper, “Net Thrust Measurement of Propellentless Microwave Thruster,” is in the June edition of the journal Acta Physica Sinica published by the Chinese Academy of Sciences. Yang's team used a magnetron as a 2.45 GHz microwave source and produced a measured thrust of up to 720 mN from 2.5 kw of input power. On the surface, this appears to be a peer-reviewed validation of the science.

（中略）

Boeing's advanced XIPS thruster, which fires out Xenon ions at high speed, achieves 165 mN of thrust from 4.5 lb. It weighs 35 lb., more than an equivalent EmDrive, and the propellant for prolonged operation can weigh much more.

（中略）

Still, the latest Chinese work may revive Western interest in the EmDrive as a viable, revolutionary technology.
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ボーイング社はイオンエンジンの研究をしているようだが、もしかしたら、
中国が全くタイプの異なる先端技術をモノにする日が近いのかもしれない・・
original news


ボーイング社のＸＩＰＳ（The xenon ion propulsion system）

original link

好きモノサイト abovetopsecret.com のニュース（約２分 前半のみ）

original link