2019 Workshop: ACTIVE EXPERIMENTS WORKSHOP

The study of plasma interactions is a key to understanding the dynamics of Earth's atmospheric regions, and the ionosphere is a particularly challenging region to study. In recent years, plasma experiments have emerged from the laboratory, where it is difficult to replicate ionospheric conditions, into the ionosphere through various active experiments. Ionospheric modification experiments using high-power HF radio waves, chemical releases from sounding rockets, or particle beams emitted from satellites can induce upper atmosphere phenomena that are observed only sporadically in the natural undisturbed ionosphere, if at all. High-power HF radio waves incident on the ionosphere can generate artificial aurora or airglow, HF-enhanced plasma and ion lines observed with radar, induce scintillations or otherwise affect radio propagation by creating plasma density irregularities due to complex interactions between the powerful HF transmissions. There are currently two HF facilities operating in US territory, the high-latitude HAARP facility in Alaska and the Arecibo Observatory in Puerto Rico at mid-latitude. HAARP is the most powerful and flexible ionospheric heater, with sweeping frequencies and multi-beam modes. Arecibo has the largest gain, up to 26 dB, and has the additional advantage of being collocated with the Arecibo ISR. Both facilities provide diagnostic optical and radio instrumentation for detecting ionospheric modification effects. Chemical releases from rockets into the natural ionosphere can also induce scintillation and even airglow, in addition to other unique effects. Recent experiments have demonstrated that artificial ionospheric layers can be created through chemical releases. For example, the Charged Aerosol Release Experiment (CARE) is designed to study artificial charged particulate (or dusty plasma) layers in the upper atmosphere and their effects on ULF, S-band, and L-band radars. This workshop will convene experimentalists to present some of their recent results and explore the potential of developing new techniques for future experiments.