Title: Digital holographic interferometry employing Fresnel transform reconstruction for the study of flow shear stabilized Z-pinch plasmas

Abstract

The ZaP-HD Flow Z-Pinch project provides a platform to explore how shear flow stabilized Z-pinches could scale to high-energy-density plasma (HEDP) and fusion reactor conditions. ZaP-HD generates shear stabilized, axisymmetric Z-pinches with stable lifetimes approaching $60$$$$\mu$$s. The goal of the project is to increase the plasma density and temperature compared to the previous ZaP project by compressing the plasma to smaller radii ($$\approx 1$$ mm). Radial and axial plasma electron density structure is measured using digital holographic interferometry (DHI), which provides the necessary fine spatial resolution. ZaP-HD's DHI system uses a 2 ns Nd:YAG laser pulse with a second harmonic generator ($$\lambda = 532$$ nm) to produce holograms recorded by a Nikon D3200 digital camera. The holograms are numerically reconstructed with the Fresnel transform reconstruction method to obtain the phase shift caused by the interaction of the laser beam with the plasma. This provides a two-dimensional map of line-integrated electron density, which can be Abel inverted to determine the local number density. The DHI resolves line-integrated densities down to $$3\times 10^{20}$$ m$$^{-2}$$ with spatial resolution near $$10 \mu$$m. This work presents the first application of Fresnel transform reconstruction as an analysis technique for a plasma diagnostic, and it analyzes the method's accuracy through study of synthetic data. It then presents an Abel inversion procedure that utilizes data on both sides of a Z-pinch local number density profile to maximize profile symmetry. Error estimation and Abel inversion are applied to measured data.

Authors:

Ross, M. P.  ^[1];

• Search DOE PAGES for author "Ross, M. P."
• Search DOE PAGES for ORCID "0000-0002-0433-5268"

Shumlak, U.  ^[1]

• Search DOE PAGES for author "Shumlak, U."
• Search DOE PAGES for ORCID "0000-0002-2918-5446"

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+ Show Author Affiliations

1. Univ. of Washington, Seattle, WA (United States). Aerospace and Energetics Research Program

Publication Date:

Wed Oct 12 00:00:00 EDT 2016

Research Org.:

Univ. of Washington, Seattle, WA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1465208

Alternate Identifier(s):

OSTI ID: 1328714

Grant/Contract Number:  

NA0001860; FG02-04ER54756

Resource Type:

Accepted Manuscript

Journal Name:

Review of Scientific Instruments

Additional Journal Information:

Journal Volume: 87; Journal Issue: 10; Journal ID: ISSN 0034-6748

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; holography; photon density; plasma flows; Z-pinch; Fourier transforms; image reconstruction; electrodes; plasma diagnostics; electron densities of states; plasma temperature