Investigation of the Properties of Imploding Plasma and the Magnetic-Field Distribution Using a Novel Spectroscopic Technique
Abstract
Under this Grant, Prof Yitzhak Maron and his team at Weizmann Institute performed small scale Z-pinch experiments. A Z-pinch uses a high current plasma discharge in a diode configuration with a gas puff in between to generate extremely high magnetic fields (B) to compress and heat up ions in a gas. The typical application of a Z-pinch is inertial confinement fusion of deuterium or lithium to generate neutrons. Using detailed spectroscopic measurements, highly resolved in both time and space, a self-generated plasma rotation, with Dr. Finch, Princeton University, and Dr. Velikovich, Naval Research Laboratory, they demonstrated using a cylindrical implosion with a pre-embedded axial magnetic field (Bz0). The rotation direction was found to depend on the direction of Bz0 and its velocity is found comparable to the peak implosion velocity, considerably affecting the force and energy balance throughout the implosion. Moreover, the evolution of the rotation is consistent with magnetic flux surface iso-rotation, a novel observation in a Z pinch, which is a prototypical time dependent system. The diagnostic methods developed by University of Weizmann include two methods: the first method used a chordal Laser-Induced-Fluorescence (LIF), where the plasma density distribution in the r - l plane, is obtained with approx. 1 millimeter resolution in a single measurement. The second plasma diagnostic method used chordal interferometry, where Abel inversion of the data gives the radial density distribution. Here, U. Weizmann obtained the density distribution for each axial location to improve the measurement accuracy. The use of the two methods simultaneously turned out to be uniquely important for substantiating the measurement reliability, and for obtaining an absolute calibration for the LIF method. In addition, Prof Maron and his team developed non-linear Stark and Zeeman diagnostic methods and analysis routines to measure the electric and magnetic fields within the Z-Pinch.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 17, 2022
- Accession Number
- AD1170148
Entities
People
- Yitzhak Maron
Organizations
- Weizmann Institute of Science