高频主动式极光研究项目(英语:High Frequency Active Auroral Research Program,常缩写为HAARP),是一个由美国空军、美国海军、国防高等研究计划署及阿拉斯加大学所共同合作的电离层研究计划。[1][2]HAARP计划在阿拉斯加加科纳(英语:Gakona, Alaska)设有一个由美国空军负责管理的研究设施,被称为HAARP研究站(HAARP Research Station)。
NRL Scientists Produce Densest Artificial Ionospheric Plasma Clouds Using HAARP (新闻稿). U.S. Naval Research Lab. 2013-02-25 [5 April 2013]. (原始内容存档于2013-03-02). Using the 3.6-megawatt high-frequency (HF) HAARP transmitter, the plasma clouds, or balls of plasma, are being studied for use as artificial mirrors at altitudes 50 kilometers below the natural ionosphere and are to be used for reflection of HF radar and communications signals. Past attempts to produce electron density enhancements have yielded densities of 4×10⁵ electrons per cubic centimeter (cm³) using HF radio transmissions near the second, third, and fourth harmonics of the electron cyclotron frequency. This frequency near 1.44 MHz is the rate that electrons gyrate around the Earth's magnetic field. The NRL group succeeded in producing artificial plasma clouds with densities exceeding 9×10⁵ electrons cm³ using HAARP transmission at the sixth harmonic of the electron cyclotron frequency.
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