Light as a Plasma Probe

Baranger, Michel; Mozer, B.

doi:10.1103/physrev.123.25

Cited by 206 publications

(63 citation statements)

References 12 publications

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“…This method has been used in many laboratories [21]- [25] since Baranger and Mozer suggested in 1961 using the high-frequency Stark effect as a diagnostic tool to study the frequency and strength of the electrostatic fluctuations in a plasma [25]. We choose the four energy-level system (3lP, 3lD, 2lP, 2lS) of helium I for spectroscopic measurement.…”

Section: Electric Field Measurementmentioning

confidence: 99%

Experimental study of a plasma-filled backward wave oscillator

Zhai¹,

Garate²,

Prohaska³

et al. 1993

IEEE Trans. Plasma Sci.

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Abstruct-We present experimental studies of a plasma-filled X-band backward wave oscillator (BWO). Depending on the background gas pressure, microwave frequency upshifts of up to 1 GHz appeared along with an enhancement by a factor of 7 in the total microwave power emission. The bandwidth of the microwave emission increased from 5 0.5 GHz to 2 GHz when the BWO was working at the rf power enhancement pressure region. The rf power enhancement appeared over a much wider pressure range in a high beam cumnt case (10-100 mT for 3 kA) as compared to a lower beam case (80-115 mT for 1.6 kA). The plasma-filled BWO has higher power output compared to the vacuum BWO over a broader region of magnetic guide field strength. Trivelpiece-Gould modes (T-G modes) are observed with frequencies up to the background plasma frequency in a plasma-filled BWO. Mode competition between the Trivelpiece-Gould modes and the X-band TMol mode prevailed when the background plasma density was below 6 x lo1' cmS3. At a critical background plasma density of ncr E 8 x 10l1 cm-3 power enhancement appeared in both X-band and the T-G modes. Power enhancement of the S-band in this mode collaboration region reached up to 8 dB. Electric fields measured by the Stark-effect method were as high as 34 kV/cm while the BWO power level was 80 MW. These electric fields lasted throughout the high power microwave pulse.

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Section: Electric Field Measurementmentioning

confidence: 99%

Experimental study of a plasma-filled backward wave oscillator

Zhai¹,

Garate²,

Prohaska³

et al. 1993

IEEE Trans. Plasma Sci.

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“…The Doppler shifts can be readily removed by measuring the Doppler shifts of emission lines originating from nearby levels of the same element that are not significantly Stark shifted and subtracting these shifts from the Stark sensitive line shifts. The second technique to measure electric fields is to measure the intensity of electric field enhanced forbidden transitions relative to nearby allowed transitions of the same element (Baranger and Mozer, 1961). The ratio of these line intensities is a direct measure of the electric field strength in the plasma while frequency measurements can be performed if satellite lines appear about the forbidden and allowed transitions (Baranger and Mozer, 1961;Cooper and Ringlet, 1969;and Davis, 1972).…”

Section: Electric Field Measurementsmentioning

confidence: 99%

Measurement of plasma wave electric fields in solar flares

Davis

1977

Sol Phys

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Measurements of electric fields in solar flares using the Stark effect exhibited by neutral helium atoms are reported. Electric field strengths as high as 700 V cm -1 are observed. Measurements of electron densities indicate that the electric fields originate from nonthermal plasma waves. Analysis of the plasma wave fields coupled with plasma density and temperature measurements indicate that the Lower Hybrid Drift instability may be present in the flaring region.

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“…In laboratory plasmas, Langmuir oscillations have for instance been observed as they were excited by electron beams interacting with the plasma [19]. The effect of Langmuir waves on hydrogen Stark profiles has been discussed for a long time in different types of plasmas [4,6,20,21]. In this context simple models for the Langmuir field are given by [20] − → E L (t) = − → E p cos(ω p t + ϕ) , where ω p is the electron plasma frequency, or by [4,5] −…”

Section: Effect Of Langmuir Wavesmentioning

confidence: 99%

Stochastic Processes Applied to the Spectroscopic Diagnostic of Hydrogen in Edge Plasmas

Hannachi

Capes

Godbert‐Mouret

et al. 2014

Contrib. Plasma Phys.

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Stochastic processes may be used as an efficient model for the line shapes affected by Stark effect in edge plasma conditions. We check the accuracy of this approach on the Lyman γ line of hydrogen perturbed by ions only. We also use a stochastic process to investigate the effect of plasma oscillations on a line shape. Our model assumes that Langmuir waves are a sequence of oscillating electric fields changing their amplitude and phase according to an exponential waiting time distribution. The possible effects of Langmuir waves on the Lyman α Stark profile are discussed in edge plasma conditions.

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Light as a Plasma Probe

Cited by 206 publications

References 12 publications

Experimental study of a plasma-filled backward wave oscillator

Experimental study of a plasma-filled backward wave oscillator

Measurement of plasma wave electric fields in solar flares

Stochastic Processes Applied to the Spectroscopic Diagnostic of Hydrogen in Edge Plasmas

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