{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,14]],"date-time":"2025-11-14T17:40:53Z","timestamp":1763142053784,"version":"build-2065373602"},"reference-count":49,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2023,4,27]],"date-time":"2023-04-27T00:00:00Z","timestamp":1682553600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Russian Science Foundation","award":["22-17-00020"],"award-info":[{"award-number":["22-17-00020"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Ducts (field-aligned plasma density enhancements) provide a link into the magnetosphere and can guide whistler waves. Inside ducts, wave-particle interactions occur efficiently; therefore, their presence contributes to the removal of energetic particles from the magnetosphere. We present experimental results concerning the characteristics, behavior, and excitation thresholds of ducts induced by extraordinary (X-mode) polarized high-power HF radio waves emitted towards the magnetic zenith (MZ) into the upper ionosphere at EISCAT (European Incoherent SCATter). The features and behavior of ducts were diagnosed by the EISCAT incoherent scatter radar (ISR) at Troms\u00f8 and the CUTLASS (SuperDARN) Finland radar at Hankasalmi. The state of the ionosphere was monitored by the Dynasonde in Troms\u00f8. It was found that the electron density Ne enhancements inside ducts were of 50\u201380% above the background Ne values and their transverse size (normal to the magnetic flux tube) corresponded to about 3\u20134\u00b0 in the north\u2013south direction. They were generated during magnetically quiet periods and extended from ~300 to 320 km up to the upper altitude limit of the EISCAT radar measurements (600\u2013700 km), when heater frequencies were both below and above the critical frequency of the F2 layer (fH \u2264 foF2 and fH &gt; foF2), regardless of whether HF-induced plasma and ion lines were generated or not. Comparing the O-\/X-mode effects from the EISCAT radar observations, it was shown that the creation of the strong Ne ducts is a typical characteristic of the X-mode pulses. As a rule, electron density enhancements were not observed during O-mode pulses. A plausible mechanism for the creation of X-mode artificial ducts is discussed.<\/jats:p>","DOI":"10.3390\/rs15092300","type":"journal-article","created":{"date-parts":[[2023,4,27]],"date-time":"2023-04-27T04:30:47Z","timestamp":1682569847000},"page":"2300","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Artificial Ducts Created via High-Power HF Radio Waves at EISCAT"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1752-3273","authenticated-orcid":false,"given":"Nataly F.","family":"Blagoveshchenskaya","sequence":"first","affiliation":[{"name":"Arctic and Antarctic Research Institute, St. Petersburg 199397, Russia"}]},{"given":"Tatiana D.","family":"Borisova","sequence":"additional","affiliation":[{"name":"Arctic and Antarctic Research Institute, St. Petersburg 199397, Russia"}]},{"given":"Alexey S.","family":"Kalishin","sequence":"additional","affiliation":[{"name":"Arctic and Antarctic Research Institute, St. Petersburg 199397, Russia"}]},{"given":"Ivan M.","family":"Egorov","sequence":"additional","affiliation":[{"name":"Arctic and Antarctic Research Institute, St. Petersburg 199397, Russia"}]}],"member":"1968","published-online":{"date-parts":[[2023,4,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1098\/rsta.1953.0011","article-title":"An investigation of whistling atmospherics","volume":"246","author":"Storey","year":"1953","journal-title":"Philos. 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