skip to main content

Title: Experiments and theory on parametric instabilities excited in HF heating experiments at HAARP

Parametric instabilities excited by O-mode HF heater and the induced ionospheric modification were explored via HAARP digisonde operated in a fast mode. The impact of excited Langmuir waves and upper hybrid waves on the ionosphere are manifested by bumps in the virtual spread, which expand the ionogram echoes upward as much as 140 km and the downward range spread of the sounding echoes, which exceeds 50 km over a significant frequency range. The theory of parametric instabilities is presented. The theory identifies the ionogram bump located between the 3.2 MHz heater frequency and the upper hybrid resonance frequency and the bump below the upper hybrid resonance frequency to be associated with the Langmuir and upper hybrid instabilities, respectively. The Langmuir bump is located close to the upper hybrid resonance frequency, rather than to the heater frequency, consistent with the theory. Each bump in the virtual height spread of the ionogram is similar to the cusp occurring in daytime ionograms at the E-F2 layer transition, indicating that there is a small ledge in the density profile similar to E-F2 layer transitions. The experimental results also show that the strong impact of the upper hybrid instability on the ionosphere can suppress the Langmuir instability.
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. New York University-Polytechnic School of Engineering, 5 Metrotech Center, Brooklyn, New York 11201 (United States)
  2. NorthWest Research Associates, P.O. Box 530, Stockton Springs, Maine 04981 (United States)
  3. Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts 02215 (United States)
  4. (United States)
Publication Date:
OSTI Identifier:
22304057
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 6; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CUSPED GEOMETRIES; DENSITY; F2 LAYER; HYBRID RESONANCE; PARAMETRIC INSTABILITIES; PLASMA; PLASMA WAVES