MRI: Development of a High Resolution Radio Imaging System for the Study of Ionospheric Radio Emissions and Structure

电离等离子体占宇宙中直接可观测物质的99%，更好地了解附近空间等离子体中的湍流可以应用于许多空间和天体物理环境，以及磁性航天器辐射屏蔽、推进(离子发动机、太阳帆)、改进天地通信和导航(GPS)链路、设备制造和聚变发电等技术问题。波多黎各阿雷西博天文台的一种新的高功率高频发射机提供了以谨慎控制的方式研究电离层等离子体的机会。该奖项是为了表彰六元中高频(中频/高频，0.3至30 MHz)成像无线电阵列的开发。该阵列将用于三个主要用途：(1)在电离层无线电波相互作用实验(加热活动)期间，对新的阿雷西博观测站发射机相对较窄的波束(约10度全宽)内产生的射电辐射进行成像、频谱和时间研究；(2)在波多黎各卡伊使用一台高频雷达进行斜角射电发射观测和多个双基地雷达观测；(3)在卡伊的高频雷达宽发射机波束内对电离层进行定向无线电发射观测和雷达成像研究。阿雷西博天文台的高频运动预计每年两次，每次大约两周，因此届时将使用临时外业站点进行数千公里尺度的成像。20公里至100公里的间隔也将使用临时外地地点进行，至少在开始时是这样。在其他时间，阵列将位于波多黎各阿瓜迪拉的美洲大学校区的一个永久地点，那里将使用10米至300米的天线间隔。12公里长的阵列(阵列1)将成像高频相互作用区的受激射电辐射(SEE)的结构，目的是确定许多SEE光谱特征相对于地球磁场的源区的确切几何形状。该阵列还将显示SEE的偏振是否在不同光谱特征之间变化。辐射的几何和偏振特性的无线电图像有望揭示辐射物理的新细节。波多黎各泛美大学的巴亚蒙校区和阿瓜迪拉校区是私立的，主要是本科院校，几乎所有的拉美裔学生都是低收入学生。将开发的仪器将增强美洲航空公司大气、空间和无线电研究基础设施的整体能力，包括正在开发的侧重大气和空间研究的研究生课程。

Ionized plasmas make up 99% of the directly observable matter in the universe, and a better understanding of turbulence in nearby space plasmas can be applied to many space and astrophysical environments, and to technological problems such as magnetic spacecraft radiation shielding, propulsion (ion engine, solar sail), improving space-to-ground communication and navigation (GPS) links, device fabrication, and fusion energy generation. A new high-power, high-frequency transmitter at the Arecibo Observatory in Puerto Rico offers opportunities to study ionospheric plasmas in a carefully controlled way. This award is for the development of a six-element medium and high-frequency (MF/HF, 0.3 to 30 MHz) imaging radio array. There will be three primary uses of the array: (1) Imaging and spectral and temporal study of radio emissions generated within the relatively narrow beam (about 10-deg full width) of the new Arecibo Observatory transmitter during ionospheric radio wave interaction experiments (heating campaigns); (2) Oblique-angle radio emission observations and multiple bistatic radar observations with an HF radar in Cayey, Puerto Rico; and (3) Direction-finding radio emission observations and radar imaging studies of the ionosphere within the wide transmitter beam of the HF radar in Cayey. Arecibo Observatory HF campaigns are anticipated to be twice a year for about two weeks each, so imaging with multi-kilometer-scale spacings would be done then, using temporary field sites. 20-km to 100-km spacings would also be done using temporary field sites, at least initially. At other times the array would be located at a permanent site at the Interamerican University campus in Aguadilla, Puerto Rico, where 10-m to 300-m antenna spacings would be used. The 12-km array (array 1) would image the structure of stimulated radio emissions (SEE) from the HF interaction region with the goal of determining the exact geometries of the source regions of the many SEE spectral features with respect to the geomagnetic field. The array would also show whether or not the polarization of SEE varies between spectral features. Radio images of the geometric and polarization properties of the emissions promise to reveal new details of the physics of the emissions. The Bayamon and Aguadilla campuses of Interamerican University of Puerto Rico are private, primarily undergraduate institutions with nearly all Hispanic, mostly low-income students. The instruments to be developed would enhance the overall capabilities of the atmospheric, space, and radio research infrastructure at Interamerican, including the ongoing development of a graduate program emphasizing atmospheric and space research.