Value chain · CLM-0167
In plain terms
A 2002 computer simulation, done because of two Japanese space-solar-power rocket experiments, modelled a different kind of plasma instability from the "self-focusing" usually discussed, and found its growth rate scales with the beam's strength. To keep the computing time down it ran at a frequency ratio far from a real microwave beam's.
The claim as recorded
Usui et al. (2002) present a 1-D electromagnetic particle-in-cell simulation of a three-wave (parametric decay-type) coupling between an intense electromagnetic pump wave, a backscattered wave, and an electrostatic wave, motivated directly by the SPS MINIX (1983) and METS (1993) rocket experiments; they state that a real experiment uses a pump of the order of 2 GHz against MHz plasma frequencies, but the simulation reduces that ratio to shorten computing time, to a pump-to-plasma frequency ratio of about 3 against about 400 in the ionosphere. The paper reports a temporal growth rate proportional to pump-wave amplitude for this instability, and does not treat thermal self-focusing.
Scope and limits
Does NOT treat thermal self-focusing/filamentation, so cannot corroborate or contradict the 0.43 coefficient; addresses a different named mechanism (parametric three-wave coupling). Not at microwave frequency: the simulated pump-to-plasma frequency ratio is about 3, against about 400 for a 2 GHz beam in the ionosphere, so its growth rates may not transfer to SPS conditions without the scaling the paper itself does not perform.
What it assumes
The paper's stated motivation (the MINIX and METS rocket experiments) accurately reflects its own framing; this is a simulation, not itself new flight data.
Where it comes from
Usui et al. (2002), Nonlin. Processes Geophys. 9, PDF p.3: "In a real experiment, we utilize a frequency of the order of 2 GHz for the pump wave, while the plasma frequency of the ionospheric plasma and the electron cyclotron frequency are both in the MHz frequency range. In the present computer experiments, however, we reduce the frequency ratio between the pump wave and the plasma characteristic waves to shorten the computational time." PDF p.8: "the ratio of the pump wave frequency to the plasma frequency is approximately 3 in the present study, while it is about 400 in an ionospheric plasma." PDF p.6: "the growth rate gamma is proportional to the amplitude of the pump wave" (the page prints the Greek letter).
Basis: none (temporal growth rate, proportional to pump field amplitude)
Related records
- Answers question
- QST-001 not published in this release
Cite this
energyaperture.com/c/clm-0167
CLM-0167, Energy Aperture, as of 2002.
Connected records
Other published records linked to this one. A list, not a judgement.