Artificial ionospheric irregularities measured with MUIR (Modular UHF Ionospheric Radar) at HAARP (High Frequency Active Auroral Research Program)

Abstract

Plasma physics is widely applied in space research, and has become a fundamental field of study, much like the fields of thermodynamics and electromagnetism. As natural phenomena, the ionosphere and magnetosphere generate and absorb plasma waves. While the science of naturally enhanced plasma waves is important to understand ionospheric/magnetospheric phenomena, artificially enhanced plasma waves also provide notable information that can help advance our understanding of both space physics and plasma physics. Many experiments on the modification of the ionosphere with high-power, High-Frequency (HF) radio waves have been conducted since the 1970s. HAARP (High Frequency Active Auroral Research Program) facility in Gakona, Alaska has played important roles in this field. MUIR (Modular UHF (Ultra High Frequency) Ionospheric Radar; 446 MHz) began operation at HAARP in February 2005. The main advantage of this radar is that its phased array system allows the beam direction to be quickly changed. The radar has been used to obtain important data sets during many HF ionospheric modification experiments. In this paper we present our findings regarding (1) HF-induced ion lines and plasma lines, (2) overshoot, and (3) Langmuir wave generation in the first 100 ms after HF turn-on.