Analytical theory of Doppler reflectometry in slab plasma model

Observation of ultrafast laser-plasma evolution by pump-probe reflectometry and Doppler spectrometry

We demonstrate pump-probe techniques, namely the Doppler spectrometry and the reflectometry in detail, which directly capture the time-resolved ultrafast evolution of high intensity femtosecond laser-driven hot, dense plasma. These techniques are capable of capturing ultrafast plasma dynamics on time scales of sub 100 femtosecond. We have shown the dynamics of high intensity femtosecond laser-driven shock like disturbance into the plasma at densities more than 10^22/cc. This can help understanding the physics related to shock ignition, supernova explosion and many other astrophysical scenarios…

Spatial and Wavenumber Resolution of Doppler Reflectometry

Doppler reflectometry spatial and wavenumber resolution is analyzed within the framework of the linear Born approximation in slab plasma model. Explicit expression for its signal backscattering spectrum is obtained in terms of wavenumber and frequency spectra of turbulence which is assumed to be radially statistically inhomogeneous. Scattering efficiency for both back and forward scattering (in radial direction) is introduced and shown to be inverse proportional to the square of radial wavenumber of the probing wave at the fluctuation location thus making the spatial resolution of diagnostics …

W7-X中的静电微湍流：局部回旋动理学模拟与多普勒反射测量的比较

Electrostatic microturbulence in W7-X: comparison of local gyrokinetic simulations with Doppler reflectometry measurements

本研究针对W7-X仿星器微湍流问题，利用stella代码开展非线性回旋动理学模拟，对比密度涨落幅度与多普勒反射测量结果并解释径向趋势，同时表征涨落与带状流频谱，为湍流研究提供理论支撑。

Interpreting Radial Correlation Doppler Reflectometry using Gyrokinetic Simulations

A linear response, local model for the DBS amplitude applied to gyrokinetic simulations shows that radial correlation Doppler reflectometry measurements (RCDR, Schirmer et al., Plasma Phys. Control. Fusion 49 1019 (2007)) are not sensitive to the average turbulence radial correlation length, but to a correlation length that depends on the binormal wavenumber $k_\perp$ selected by the Doppler backscattering (DBS) signal. Nonlinear gyrokinetic simulations show that the turbulence naturally exhibits a non-separable power law spectrum in wavenumber space, leading to a power law dependence of the r…

等离子体径向电场和密度波动的测量：在W7-X装置中后弹丸增强约束相中的多普勒反射仪测量

Radial electric field and density fluctuations measured by Doppler reflectometry during the post-pellet enhanced confinement phase in W7-X

本研究通过多普勒反射仪测量了W7-X装置后弹丸增强约束相中的等离子体径向电场和密度波动，发现径向电场凹陷与等离子体参数相关，并通过模拟揭示了等离子体剖面演变和径向电场对湍流稳定的作用。

Full-Wave Feasibility Study of Anti-Radar Diagnostic of Magnetic Field Based on O-X Mode Conversion and Oblique Reflectometry Imaging

An innovative millimeter wave diagnostic is proposed to measure the local magnetic field and edge current as a function of the minor radius in the tokamak pedestal region. The idea is to identify the direction of minimum reflectivity at the O-mode cutoff layer. Correspondingly, the transmissivity due to O-X mode conversion is maximum. That direction, and the angular map of reflectivity around it, contain information on the magnetic field vector B at the cutoff layer. Probing the plasma with different wave frequencies provides the radial profile of B. Full-wave finite-element simulations are pr…