Title: Study of stability in a liner-on-target gas puff Z-pinch as a function of pre-embedded axial magnetic field

Abstract

Gas puff Z-pinches are intense sources of X-rays and neutrons but are highly susceptible to the magneto-Rayleigh-Taylor instability (MRTI). MRTI mitigation is critical for optimal and reproducible yields, motivating significant attention toward various potential mitigation mechanisms. One such approach is the external application of an axial magnetic field, which will be discussed here in the context of recent experiments on the Zebra generator (1 MA, 100 ns) at the University of Nevada, Reno. In these experiments, an annular Kr gas liner is imploded onto an on-axis deuterium target with a pre-embedded axial magnetic field B_z0 ranging from 0 to 0.3 T. The effect of B_z0 on the stability of the Kr liner is evaluated with measurements of plasma radius, overall instability amplitude, and dominant instability wavelength at different times obtained from time-gated extreme ultraviolet pinhole images. It was observed that the external axial magnetic field does not affect the implosion velocity significantly and that it reduces the overall instability amplitude and the presence of short-wavelength modes, indicating improved pinch stability and reproducibility. For the highest applied B_z0 = 0.3 T, the stagnation radius measured via visible streak images was found to increase. These findings are consistent with experiments reported inmore » the literature, but here, the B_z0 required for stability, Bz0 = 0.13 I_pk=R₀ (where I_pk is the driver peak current and R₀ is the initial radius), is lower. This could be attributed to the smaller load geometry, both radially and axially. Consistent with other experiments, the cause of decreased convergence cannot be explained by the additional axial magnetic pressure and remains an open question.« less

Authors:

Conti, F.  ^[1];

• Search DOE PAGES for author "Conti, F."
• Search DOE PAGES for ORCID "0000-0003-2270-0473"
• Search orcid.org for ORCID "0000-0003-2270-0473"

Aybar, N. ^[1]; Narkis, J.  ^[1];

• Search DOE PAGES for author "Narkis, J."
• Search DOE PAGES for ORCID "0000-0001-5436-8933"
• Search orcid.org for ORCID "0000-0001-5436-8933"

Valenzuela, J. C.  ^[2];

• Search DOE PAGES for author "Valenzuela, J. C."
• Search DOE PAGES for ORCID "0000-0001-8499-4599"
• Search orcid.org for ORCID "0000-0001-8499-4599"

Rahman, H. U. ^[3]; Ruskov, E.  ^[3];

• Search DOE PAGES for author "Ruskov, E."
• Search DOE PAGES for ORCID "0000-0003-3672-4580"
• Search orcid.org for ORCID "0000-0003-3672-4580"

Dutra, E. ^[4]; Haque, S. ^[5]; Covington, A. ^[5]; Beg, F. N. ^[1]

---

+ Show Author Affiliations

1. Univ. of California, San Diego, CA (United States)
2. Univ. of California, San Diego, CA (United States); Pontifical Catholic Univ. of Chile, Santiago (Chile)
3. Magneto-Inertial Fusion Technologies, Inc., Tustin, CA (United States)
4. Univ. of Nevada, Reno, NV (United States); Livermore Operations, Livermore, CA (United States)
5. Univ. of Nevada, Reno, NV (United States)

Publication Date:

2020-01-09

Research Org.:

Univ. of California, San Diego, CA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); USDOE Advanced Research Projects Agency - Energy (ARPA-E)

OSTI Identifier:

1633887

Alternate Identifier(s):

OSTI ID: 1581845

Grant/Contract Number:  

NA0003842; AR0000569

Resource Type:

Accepted Manuscript

Journal Name:

Physics of Plasmas

Additional Journal Information:

Journal Volume: 27; Journal Issue: 1; Journal ID: ISSN 1070-664X

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY