Second harmonic generation in a laser plasma (review)

Basov, N G; Bychenkov, V. Yu.; Крохин, О. Н.; Осипов, М. В.; Rupasov, A. A.; Silin, V. P.; Sklizkov, G. V.; Starodub, A. N.; Tikhonchuk, V. T.; Shikanov, A. S.

doi:10.1070/qe1979v009n09abeh009430

Cited by 38 publications

(19 citation statements)

References 12 publications

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“…Caruso et al () describe one of the first observations of radiation at the second harmonic (SH) of the incident laser frequency in a laser‐produced plasma. Two primary mechanisms (Basov et al, ) responsible for SHG occurring near plasma resonance when a high‐power laser interacts with an unmagnetized plasma are as follows: In the first mechanism, SHG starts with the linear conversion of the incident Laser radiation O of frequency ω o into Langmuir oscillations L of frequency ω L . In the linear conversion ω o ≈ ω L .…”

Section: Introductionmentioning

confidence: 99%

“…Since frequency matching requires ω o = ω L + ω I A , subsequent mixing

O + L \Rightarrow ω_{o} + ω_{L} = 2 ω_{o} - ω_{IA}

L + L \Rightarrow ω_{L} + ω_{L} = 2 ω_{o} - 2 ω_{IA}

produces radiation downshifted from the SH of the incident laser radiation frequency by either the ion‐acoustic frequency or twice the ion‐acoustic frequency, respectively. Even for a small excess of the PW energy density over the PDI threshold in the plasma resonance region, the energy density of the parametrically excited Langmuir waves equals or exceeds that of the PW making the L + L mixing more dominant than the O + L (Basov et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…Fundamental theory and experimentation in second harmonic generation (SHG) is longstanding in studies of the interaction between high‐power lasers and unmagnetized plasmas (e.g., Basov et al, ). SHG provides useful diagnostic information such as wave hydrodynamic evolution, wave absorption processes, local temperature, characteristic density inhomogeneity scale, and parametric turbulence of laser plasmas (Basov et al, ) and thus could provide similar diagnostic information for ionospheric plasma. This is the main motivation for the investigation and results presented here.…”

Section: Introductionmentioning

confidence: 99%

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First Observations of Narrowband Stimulated Electromagnetic Emissions at the Pump Frequency Second Harmonic During Ionosphere Interaction Experiments

Yellu

Scales

Mahmoudian

et al. 2018

Geophysical Research Letters

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Reported herein are first observations of narrowband stimulated electromagnetic emissions (NSEEs) within ±30 Hz of the second harmonic of the pump wave frequency during ionospheric heating experiments at the High Frequency Active Auroral Research Program facility. The observations are juxtaposed with contemporaneous NSEEs observed within ±30 Hz of the pump wave frequency. The transmit power of the pump wave is linearly increased, and the pump wave frequency is stepped through frequencies near the third electron gyroharmonic frequency during the experiment. The first observation is that there is a transmit power threshold for the occurrence of NSEEs downshifted from the second harmonic of the pump wave frequency. Secondly, when downshifted NSEEs are present at both the pump frequency and its second harmonic, the transmit power threshold for the onset of both are comparable. Third, the frequency offset of the downshifted NSEEs spectral line from the second harmonic frequency is approximately twice the frequency offset of the downshifted NSEEs spectral line from the pump wave frequency when the downshifted NSEEs are present near both the pump and second harmonic frequency. Finally, the NSEEs at the second harmonic of the pump wave frequency are suppressed at pump frequencies very close to the third electron gyroharmonic frequency.

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Section: Introductionmentioning

confidence: 99%

“…Since frequency matching requires ω o = ω L + ω I A , subsequent mixing

O + L \Rightarrow ω_{o} + ω_{L} = 2 ω_{o} - ω_{IA}

L + L \Rightarrow ω_{L} + ω_{L} = 2 ω_{o} - 2 ω_{IA}

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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First Observations of Narrowband Stimulated Electromagnetic Emissions at the Pump Frequency Second Harmonic During Ionosphere Interaction Experiments

Yellu

Scales

Mahmoudian

et al. 2018

Geophysical Research Letters

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“…SHG can provide important qualitative diagnostics of the modified ionosphere during ionospheric heating. An assessment of the structure of 2nd harmonic spectra provides information about processes occurring in the plasma Basov et al (). The 2‐component structure observed in Figures 3c and 10c indicates that both linear and nonlinear processes are occurring in the plasma.…”

Section: Discussionmentioning

confidence: 99%

Pump Power Effects on Second Harmonic Stimulated Electromagnetic Emissions During Ionosphere Heating

et al. 2019

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Due to the potential for new diagnostic capabilities, there has been renewed interest in the generation of ionospheric stimulated electromagnetic emissions (SEEs) near the second harmonic of the pump frequency ( 0 ), a process known as second harmonic generation (SHG). Observations of SHG during experiments at the High Frequency Active Auroral Research Program facility in which 0 was stepped near the third harmonic of the electron gyrofrequency, 3 ce , and the transmit power linearly increased over the heating cycle at each 0 , were reported recently. A key observation was the linkage between SEEs within ±30 Hz of 0 , due to stimulated Brillouin scatter, and within ±30 Hz of 2 0 . This current work reports further High Frequency Active Auroral Research Program observations that compare the time evolution of SEEs including SHG under the following two transmit power conditions (I) linear power ramp (II) maximum available power (2.8 MW). During these experiments, 0 was stepped near 3 ce and also 2 ce . The results show that SEEs within ±100 Hz of 0 and 2 0 are both suppressed within a few seconds when the ionosphere is irradiated with the maximum available power. These SEEs appear to be suppressed before the onset of field-aligned irregularities at the upper hybrid layer which is not in line with previous reports. Thus, other mechanisms, which are discussed, could possibly be responsible for the observed suppression of stimulated Brillouin scatter and SHG. Some preliminary diagnostics are derived from the SHG spectra temporal evolution by leveraging concepts from the field of laser plasma interactions.

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“…Since the second harmonic emission from laser produced plasmas is one of the most important aspects of nonlinear interaction between laser and plasmas, many authors have extensively studied the problem theoretically and experimentally (Auer et al 1979;Bobin et al 1973;Basov et al 1979;Erokhin et al 1969;1974;Gu Min et al 1987;Jackel et al 1981;Tan Weihan et al 1982;Tanaka et al 1984). Results show that there are two mechanisms for the second harmonic emission: one is called linear conversion, which means that the incident energy is directly converted into the 2co o harmonic energy by resonance absorption near the critical surface, and the other is parametric decay, in which one incident photon parametrically decays into an electron-plasmon and an ion-acoustic phonon.…”

Section: Introductionmentioning

confidence: 99%

Linear conversion theory on the second harmonic emission from a plasma filament

Tan¹,

Gu²

1989

Laser Part. Beams

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The linear conversion theory of laser produced plasma filaments is studied in this paper. By calculations for the energy flux of the second harmonic emission on the basis of the planar wave-plasma interaction model, it has been found that there exists no 2w Q harmonic emission in the direction perpendicular to the incident laser, in contradiction with the experiments. Therefore, we have proposed a linear conversion theory on the second harmonic emission from a plasma filament and discovered the intense 2CJ 0 harmonic emission in the direction perpendicular to the incident laser, which is in agreement with the experiments. The second harmonic energy fluxAccording to Erokhin et al. (1974), the 2(o 0 harmonic electro-magnetic field satisfies the following equations c V x £ 2 = -i2co Q H 2 , D = e 2 E 2 , 0263-0364/89/0701-0131S05.00

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Second harmonic generation in a laser plasma (review)

Cited by 38 publications

References 12 publications

First Observations of Narrowband Stimulated Electromagnetic Emissions at the Pump Frequency Second Harmonic During Ionosphere Interaction Experiments

First Observations of Narrowband Stimulated Electromagnetic Emissions at the Pump Frequency Second Harmonic During Ionosphere Interaction Experiments

Pump Power Effects on Second Harmonic Stimulated Electromagnetic Emissions During Ionosphere Heating

Linear conversion theory on the second harmonic emission from a plasma filament

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