Related Experiment Video
Updated: Jun 7, 2026
11:00
Experimental Investigation of Secondary Flow Structures Downstream of a Model Type IV Stent Failure in a 180° Curved Artery Test Section
Published on: July 19, 2016
Two-point motional Stark effect diagnostic for Madison Symmetric Torus
J Ko1, D J Den Hartog, K J Caspary
1University of Wisconsin-Madison, Madison, Wisconsin 53706, USA. jko6@wisc.edu
The Review of Scientific Instruments
|November 2, 2010
Summary
A new analysis method for spectral motional Stark effect (MSE) diagnostics improves magnetic field measurements in Madison Symmetric Torus (MST) plasmas. Adding off-axis measurements significantly enhances the accuracy of reconstructed plasma profiles.
Area of Science:
- Plasma physics
- Magnetic confinement fusion
- Spectroscopy
Background:
- The Madison Symmetric Torus (MST) utilizes spectral motional Stark effect (MSE) diagnostics for internal magnetic field measurements.
- Current MSE diagnostics in MST employ two spatial views: on the magnetic axis and at the midminor radius.
Purpose of the Study:
- To develop a novel analysis scheme for inferring magnetic field pitch angle and magnitude from MSE spectra.
- To evaluate the impact of adding an off-axis spatial view to MSE diagnostics on plasma profile reconstruction.
Main Methods:
- A new analysis scheme was developed to process MSE spectra.
- Atomic data from the Atomic Data and Analysis Structure (ADAS) were integrated to minimize systematic errors.
- Magnetic field pitch angle and magnitude were inferred from spectral data.
Main Results:
- The new analysis scheme successfully infers both pitch angle and magnetic field magnitude from MSE spectra.
- Reconstructed current density and safety factor profiles show improved global constraints with the inclusion of off-axis MSE measurements compared to on-axis measurements alone.
Conclusions:
- The enhanced MSE diagnostic analysis provides more robust internal magnetic field measurements for MST plasmas.
- The addition of off-axis MSE measurements significantly improves the accuracy and global constraint of reconstructed plasma profiles, crucial for understanding plasma behavior in fusion devices.
Related Concept Videos
01:28Symmetry in Maxwell's Equations
Once the fields have been calculated using Maxwell's four equations, the Lorentz force equation gives the force that the fields exert on a charged particle moving with a certain velocity. The Lorentz force equation combines the force of the electric field and of the magnetic field on the moving charge. Maxwell's equations and the Lorentz force law together encompass all the laws of electricity and magnetism. The symmetry that Maxwell introduced into his mathematical framework may not be...
01:15Torque Free Motion
The torque-free motion refers to the movement of a rigid body in space when no external torques are acting upon it. This type of motion can be observed in environments where there are no external forces or frictions, like in outer space. For example, a rotation of Mars in space is a torque-free motion. Mars is an axisymmetric object, meaning it has an axis of symmetry along which it rotates, designated as the z-axis. The rotating frame of reference is defined such that the center of mass of...
01:23Mohr's Circle for Plane Stress
Mohr's circle is a graphical method for identifying the state of stress at a point in a material, making it easier to analyze stress transformations under plane stress conditions. This two-dimensional technique visualizes both normal and shearing stresses on an element.
Consider a set of Cartesian coordinates. The horizontal and vertical axes correspond to normal stress (σ) and shearing stress (τ), respectively. Two points, points A and B, are defined by the normal and shear stresses on the...
Consider a set of Cartesian coordinates. The horizontal and vertical axes correspond to normal stress (σ) and shearing stress (τ), respectively. Two points, points A and B, are defined by the normal and shear stresses on the...
01:24Potential Due to a Magnetized Object
Magnetic dipoles in magnetic materials are aligned when placed under an external magnetic field. For paramagnets and ferromagnets, dipole alignment occurs in the direction of the magnetic field. However, the dipoles align opposite to the field in the case of diamagnets. This state of magnetic polarization due to the external field is called magnetization. Magnetization is defined as the dipole moment per unit volume. It plays a similar role to polarization in electrostatics.
The vector...
The vector...
01:15Thin-Walled Hollow Shafts
In analyzing a thin-walled hollow shaft subjected to torsional loading, a segment with width dx is isolated for examination. Despite its equilibrium state, this segment faces torsional shearing forces at its ends. These forces are quantitatively described by the product of the longitudinal shearing stress on the segment's minor surface and the area of this surface, leading to the concept of shear flow. This shear flow is consistent throughout the structure, indicating a uniform distribution of...
01:20Gauss's Law: Cylindrical Symmetry
A charge distribution has cylindrical symmetry if the charge density depends only upon the distance from the axis of the cylinder and does not vary along the axis or with the direction about the axis. In other words, if a system varies if it is rotated around the axis or shifted along the axis, it does not have cylindrical symmetry. In real systems, we do not have infinite cylinders; however, if the cylindrical object is considerably longer than the radius from it that we are interested in,...