Related Experiment Video
Updated: Jun 27, 2026
09:10
The Frequency Domain Thermoreflectance Technique for Thermal Property Measurements
Published on: December 5, 2025
First density profile measurements using frequency modulation of the continuous wave reflectometry on JET
L Meneses1, L Cupido, A Sirinelli
1JET-EFDA, Culham Science Centre, OX14 3DB, Abingdon, United Kingdom.
The Review of Scientific Instruments
|December 17, 2008
Summary
An innovative X-mode reflectometer was installed at JET to measure plasma density profiles. This diagnostic demonstrates high sensitivity in ITER-relevant regimes, paving the way for future fusion devices.
Area of Science:
- Plasma physics
- Fusion energy research
- Diagnostic instrumentation
Background:
- Fusion devices like JET require precise plasma diagnostics.
- Measuring plasma density profiles is crucial for understanding fusion processes.
- Complex transmission lines in fusion devices pose challenges for reflectometry.
Purpose of the Study:
- To design and implement an X-mode reflectometer at JET.
- To demonstrate high spatial and temporal resolution density profile measurements.
- To validate broadband reflectometry in complex transmission lines for ITER-relevant regimes.
Main Methods:
- Development and installation of an X-mode reflectometer at JET.
- Utilizing broadband reflectometry in the V band (0-1.4x10^19 m^-3) with magnetic fields of 2.4-3.0 T.
- Testing the diagnostic in ITER-relevant regimes, including ELMy H-modes.
Main Results:
- Successful installation and operation of the X-mode reflectometer at JET.
- Demonstrated high sensitivity in measuring plasma density profile changes.
- Experimental validation of broadband reflectometry in complex transmission lines.
Conclusions:
- The X-mode reflectometer is a viable diagnostic for high-resolution density profiling.
- The technology is suitable for ITER-relevant plasma conditions.
- This success led to an upgrade of the frequency modulation of the continuous wave (FMCW) reflectometry for edge and core probing, essential for next-step fusion devices.
Related Concept Videos
01:07Propagation of Waves
When a wave propagates from one medium to another, part of it may get reflected in the first medium, and part of it may get transmitted to the second medium. In such a case, the interface of the two mediums can be considered as a boundary that is neither fixed nor free.
Consider a scenario where a wave propagates from a string of low linear mass density to a string of high linear mass density. In such a case, the reflected wave is out of phase with respect to the incident wave, however the...
Consider a scenario where a wave propagates from a string of low linear mass density to a string of high linear mass density. In such a case, the reflected wave is out of phase with respect to the incident wave, however the...
01:17NMR Spectrometers: Radiofrequency Pulses and Pulse Sequences
A pulse is a short burst of radio waves distributed over a range of frequencies that simultaneously excites all the nuclei in the sample. Upon passing a radio frequency pulse along the x-axis, the nuclei absorb energy corresponding to their Larmor frequencies and achieve resonance. This shifts the net magnetization vector from the z-axis toward the transverse plane. This angle of rotation of the magnetization vector, or the flip angle, is proportional to the duration and intensity of the pulse.
01:26Raman Spectroscopy Instrumentation: Overview
A conventional Raman spectrophotometer includes a laser source, a sample holding system, a wavelength selector, and a detector.
The monochromatic laser source, typically using visible or near-infrared radiation, generates a highly focused beam of light. This light interacts with the molecules of the sample, scattering some of the light. Liquid and gaseous samples are usually tested in ordinary glass capillaries, while solids can be analyzed as powders packed in capillaries or as potassium...
The monochromatic laser source, typically using visible or near-infrared radiation, generates a highly focused beam of light. This light interacts with the molecules of the sample, scattering some of the light. Liquid and gaseous samples are usually tested in ordinary glass capillaries, while solids can be analyzed as powders packed in capillaries or as potassium...