New applications of the portable heater. Gennady Milikh, UMD-SPP group

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1 New applications of the portable heater Gennady Milikh, UMD-SPP group 1

2 Stabilization of equatorial spread F (ESF) by ion injection 2

3 ESF characterizes spreading in the height of F-region backscatter return on the ionogram. It is caused by irregularities of the normally smooth F-region density profile. The irregularities can occur at any latitude, they are pronounced at the equator where they can grow in the large scale plasma bubbles. It is driven by the generalized Rayleigh-Taylor instabilities. Equatorial Spread F (ESF) impacts Command, Control, and Communication (C3). systems. 3

4 Generalized Rayleigh-Taylor instability in the equatorial ionosphere Background conditions (the top panel), a dense fluid is on the top of a light fluid. Charge builds up at the edges of the depletion, which generates polarization field (the bottom panel). The plasma drifts upward in ExB field enlarging the depletion. 4

5 Simulations of ESF bubble triggered with a density perturbation (two left images). A similar simulation that uses HF heating as the density perturbation seed. In this case 5 no ESF bubble is formed (two right images). [Zawdie and Huba, 2014].

6 Stabilization of Equatorial Spread F Higher Density, n Lower Density, n - Δn F-region Local Magnetic Field Main Beam Portable HF Heater 6

7 Experimental observations of artificial ionospheric ducts The DEMETER and DMSP satellites were used, and detected ducts during their closest approach to HAARP Vartanyan et al. [2012] 7

8 Formation of the artificial ionospheric ducts and intensity of the ion fluxes were modeled with the help of the modified SAMI2 code. The SAMI2 model is inter-hemispheric and can simulate the plasma along the entire dipole magnetic field line. We have modified SAMI2 by introducing a flexible source of electron heating by HF radiation. The original SAMI2 code was developed at NRL (Dr Huba was PI on the project). Our work was conducted in close collaboration with the NRL group. 8

9 Comparison of SAMI2 simulations with satellite observations DEMETER (left) and DMSP15 (right) observations along with SAMI2 simulation results. 9

10 We propose to conduct preliminary analysis on the ESF stabilization by ion injection due to the ionospheric HF heating. This includes: - Estimate the ion flux needed to stabilize the ESF under different geomagnetic latitude, and varying ionospheric conditions, using the existing theory of the RT instability. - Find ERP and HF heating frequency required to produce such ion flux. - Provide recommendations for future experiments with the portable HF heater. 10

11 Generating the artificial ionospheric turbulence (AIT) by X-mode heating 11

12 - In the existing experiments the AIT is generated by O-mode waves which are anomalously absorbed in a thin layer between the reflection altitude and upper hybrid altitude. - The portable HF heater will radiate O-mode HF waves vertically, thus the heating efficiency will be reduced by the Spitze angle limitations. (Rays with χ > χ SS are reflected below the upper hybrid layer, and are lost). 12

Sometimes help comes from unexpected places. Experiments by Xiang Wang [2016] and Blagoveshchenskaya et al. [2015] conducted at EISCAT facility (Norway) using HF heater and UHF radar.

13 Sometimes help comes from unexpected places. Experiments by Xiang Wang [2016] and Blagoveshchenskaya et al. [2015] conducted at EISCAT facility (Norway) using HF heater and UHF radar. O-mode and X-mode were used. Down-shifted plasma line (frequency offset, MHz vs. time). Down-shifted plasma line (altitude vs. time) Ion line (freq. offset, khz vs. time) Downshifted ion line spectra (altitude vs. time) Plasma and Ion lines are produced by the X-mode only Zero frequency ion line spectra (altitude vs. time) The electron heating is produced by the O- and X- mode. Upshifted ion line spectra (altitude vs. time) Electron temperature 13

14 Plasma and Ion lines are attributed to parametric instability excited by the parallel component Epar of electric field of X-mode wave near its reflection height. The Epar can exceed the threshold of parametric instability, which is as low as 0.1V/m. As a result strong electron heating was generated, and at some conditions it can exceed heating generated by O-mode. 14

15 We propose to conduct preliminary analysis on the parametric decay instability due to the ionospheric HF heating. This includes: - Obtain the instability threshold under different geomagnetic latitude, and varying ionospheric conditions, using the existing theory. - Find ERP and HF heating frequency required to produce such instability, then estimate the expected electron temperature magnification. - Provide recommendations for future experiments with the portable HF heater. 15

HAARP-induced Ionospheric Ducts

HAARP-induced Ionospheric Ducts Gennady Milikh, University of Maryland in collaboration with: Dennis Papadopoulos, Chia-Lee Chang, Hira Shroff, BAE systems Evgeny Mishin, AFRL/RVBXI, Hanscom AFB Michel