Two-color scattering for the measurement of neutrals at the edge of fusion devices.

Rev Sci Instrum

Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, USA.

Published: June 2021


Category Ranking

98%

Total Visits

921

Avg Visit Duration

2 minutes

Citations

20

Article Abstract

Laser two-color scattering (TCS) is proposed to detect the neutral species in the edge of fusion devices, namely, tokamaks. TCS uses two wavelengths to probe both the laser Rayleigh scattering and Thomson scattering of the neutral-electron bath, with emphasis on neutral density measurements such as that of hydrogen and deuterium. Modeling of the Rayleigh scattering of tokamak neutral species under various plasma conditions (electron density and temperature) shows that, with an appropriate filtering of the Thomson signal and by going to ultraviolet-region wavelengths, identification of the Rayleigh signal can be achieved. Photon count and signal fractions are calculated in two test cases, one in the midplane region of the National Spherical Torus Experiment and one in the divertor region of DIII-D. An uncertainty analysis and discussion of the feasibility of the TCS diagnostic is also presented.

Download full-text PDF

Source
http://dx.doi.org/10.1063/5.0027481DOI Listing

Publication Analysis

Top Keywords

two-color scattering
8
edge fusion
8
fusion devices
8
neutral species
8
rayleigh scattering
8
scattering measurement
4
measurement neutrals
4
neutrals edge
4
devices laser
4
laser two-color
4

Similar Publications

Probing and manipulating the spatiotemporal dynamics of hot carriers in nanoscale metals is crucial to a plethora of applications ranging from nonlinear nanophotonics to single-molecule photochemistry. The direct investigation of these highly non-equilibrium carriers requires the experimental capability of high energy-resolution (~ meV) broadband femtosecond spectroscopy. When considering the ultimate limits of atomic-scale structures, this capability has remained out of reach until date.

View Article and Find Full Text PDF

High-energy vortex γ photons have significant applications in many fields. However, their generation and angular momentum manipulation are still great challenges. Here, we first investigated the generation of vortex γ photons with controllable spin and orbital angular momenta via nonlinear Compton scattering of two-color counter-rotating circularly polarized (CP) laser fields.

View Article and Find Full Text PDF

The physical picture for photocurrent injection and coherent control in intrinsic graphene under two-color laser excitation remains obscure. Previously, photocurrent injection of intrinsic graphene was attributed to the quantum interference between two electronic transition pathways of single-photon and two-photon absorptions as well as layer-to-layer coupling. Here, we show that quantum interference between stimulated electronic Raman scattering and single-photon absorption plays a very important role in contributing to the total photocurrent, while interlayer coupling does not sufficiently affect the photocurrent injection, which is in contrast to the previous interpretation of the experimental results on photocurrent injection and coherent control.

View Article and Find Full Text PDF

Optical imaging access to nanometer-level protein distributions in intact tissue is a highly sought-after goal, as it would provide visualization in physiologically relevant contexts. Under the unfavorable signal-to-background conditions of increased absorption and scattering of the excitation and fluorescence light in the complex tissue sample, superresolution fluorescence microscopy methods are severely challenged in attaining precise localization of molecules. We reasoned that the typical use of a confocal detection pinhole in MINFLUX nanoscopy, suppressing background and providing optical sectioning, should facilitate the detection and resolution of single fluorophores even amid scattering and optically challenging tissue environments.

View Article and Find Full Text PDF

XFEL Beamline Optical Instrumentation for Ultrafast Science.

J Phys Chem B

September 2024

Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, United Kingdom.

Free electron lasers operating in the soft and hard X-ray regime provide capabilities for ultrafast science in many areas, including X-ray spectroscopy, diffractive imaging, solution and material scattering, and X-ray crystallography. Ultrafast time-resolved applications in the picosecond, femtosecond, and attosecond regimes are often possible using single-shot experimental configurations. Aside from X-ray pump and X-ray probe measurements, all other types of ultrafast experiments require the synchronized operation of pulsed laser excitation for resonant or nonresonant pumping.

View Article and Find Full Text PDF