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Dive into the research topics where D. A. Yager-Elorriaga is active.

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Featured researches published by D. A. Yager-Elorriaga.


Physics of Plasmas | 2016

Seeded and unseeded helical modes in magnetized, non-imploding cylindrical liner-plasmas

D. A. Yager-Elorriaga; Peng Zhang; A.M. Steiner; N.M. Jordan; Y. Y. Lau; Ronald M. Gilgenbach

In this research, we generated helical instability modes using unseeded and kink-seeded, non-imploding liner-plasmas at the 1 MA Linear Transformer Driver facility at the University of Michigan in order to determine the effects of externally applied, axial magnetic fields. In order to minimize the coupling of sausage and helical modes to the magneto Rayleigh-Taylor instability, the 400 nm-thick aluminum liners were placed directly around straight-cylindrical (unseeded) or threaded-cylindrical (kink-seeded) support structures to prevent implosion. The evolution of the instabilities was imaged using a combination of laser shadowgraphy and visible self-emission, collected by a 12-frame fast intensified CCD camera. With no axial magnetic field, the unseeded liners developed an azimuthally correlated m = 0 sausage instability (m is the azimuthal mode number). Applying a small external axial magnetic field of 1.1 T (compared to peak azimuthal field of 30 T) generated a smaller amplitude, helically oriented inst...


Review of Scientific Instruments | 2015

Technique for fabrication of ultrathin foils in cylindrical geometry for liner-plasma implosion experiments with sub-megaampere currents

D. A. Yager-Elorriaga; A.M. Steiner; Sonal Patel; N.M. Jordan; Y. Y. Lau; Ronald M. Gilgenbach

In this work, we describe a technique for fabricating ultrathin foils in cylindrical geometry for liner-plasma implosion experiments using sub-MA currents. Liners are formed by wrapping a 400 nm, rectangular strip of aluminum foil around a dumbbell-shaped support structure with a non-conducting center rod, so that the liner dimensions are 1 cm in height, 6.55 mm in diameter, and 400 nm in thickness. The liner-plasmas are imploded by discharging ∼600 kA with ∼200 ns rise time using a 1 MA linear transformer driver, and the resulting implosions are imaged four times per shot using laser-shadowgraphy at 532 nm. This technique enables the study of plasma implosion physics, including the magneto Rayleigh-Taylor, sausage, and kink instabilities on initially solid, imploding metallic liners with university-scale pulsed power machines.


Physics of Plasmas | 2016

Discrete helical modes in imploding and exploding cylindrical, magnetized liners

D. A. Yager-Elorriaga; Peng Zhang; A.M. Steiner; N.M. Jordan; P. C. Campbell; Y. Y. Lau; Ronald M. Gilgenbach

Discrete helical modes have been experimentally observed from implosion to explosion in cylindrical, axially magnetized ultrathin foils (Bz = 0.2 – 2.0 T) using visible self-emission and laser shadowgraphy. The striation angle of the helices, ϕ, was found to increase during the implosion and decrease during the explosion, despite the large azimuthal magnetic field (>40 T). These helical striations are interpreted as discrete, non-axisymmetric eigenmodes that persist from implosion to explosion, obeying the simple relation ϕ = m/kR, where m, k, and R are the azimuthal mode number, axial wavenumber, and radius, respectively. Experimentally, we found that (a) there is only one, or at the most two, dominant unstable eigenmode, (b) there does not appear to be a sharp threshold on the axial magnetic field for the emergence of the non-axisymmetric helical modes, and (c) higher axial magnetic fields yield higher azimuthal modes.


Physics of Plasmas | 2016

Determination of plasma pinch time and effective current radius of double planar wire array implosions from current measurements on a 1-MA linear transformer driver

A.M. Steiner; D. A. Yager-Elorriaga; Sonal Patel; Nicholas M. Jordan; Ronald M. Gilgenbach; A.S. Safronova; V. L. Kantsyrev; V.V. Shlyaptseva; I. Shrestha; Maximillian T. Schmidt-Petersen

Implosions of planar wire arrays were performed on the Michigan Accelerator for Inductive Z-pinch Experiments, a linear transformer driver (LTD) at the University of Michigan. These experiments were characterized by lower than expected peak currents and significantly longer risetimes compared to studies performed on higher impedance machines. A circuit analysis showed that the load inductance has a significant impact on the current output due to the comparatively low impedance of the driver; the long risetimes were also attributed to high variability in LTD switch closing times. A circuit model accounting for these effects was employed to measure changes in load inductance as a function of time to determine plasma pinch timing and calculate a minimum effective current-carrying radius. These calculations showed good agreement with available shadowgraphy and x-ray diode measurements.


IEEE Transactions on Plasma Science | 2016

Double and Single Planar Wire Arrays on University-Scale Low-Impedance LTD Generator

A.S. Safronova; V. L. Kantsyrev; M.E. Weller; V.V. Shlyaptseva; I. Shrestha; Mindy Y. Lorance; Maximillian T. Schmidt-Petersen; A. Stafford; M.C. Cooper; A.M. Steiner; D. A. Yager-Elorriaga; Sonal Patel; Nicholas M. Jordan; Ronald M. Gilgenbach; Alexander S. Chuvatin

Planar wire array (PWA) experiments were performed on Michigan Accelerator for Inductive Z-pinch Experiments, the University of Michigans low-impedance linear transformer driver (LTD)-driven generator (0.1 Ω, 0.5-1 MA, and 100-200 ns), for the first time. It was demonstrated that Al wire arrays [both double PWA (DPWA) and single PWA (SPWA)] can be successfully imploded at LTD generator even at the relatively low current of 0.3-0.5 MA. In particular, implosion characteristics and radiative properties of PWAs of different load configurations [for DPWA from Al and stainless steel wires with different wire diameters, interwire gaps, and interplanar gaps (IPGs) and for Al SPWA of different array widths and number of wires] were studied. The major difference from the DPWA experiments on high-impedance Zebra accelerator was in the current rise time that was influenced by the load inductance and was increased up to about 150 ns during the first campaign (and was even longer in the second campaign). The implosion dynamics of DPWAs strongly depends on the critical load parameter, the aspect ratio (the ratio of the array width to IPG) as for Al DPWAs on high-impedance Zebra, but some differences were observed, for low-aspect ratio loads in particular. Analysis of X-ray images and spectroscopy indicates that K-shell Al plasmas from Al PWAs reached the electron temperatures up to more than 450 eV and densities up to 2 × 1020 cm-3. Despite the low mass of the loads, opacity effects were observed in the most prominent K-shell Al lines almost in every shot.


Physics of Plasmas | 2018

The electro-thermal stability of tantalum relative to aluminum and titanium in cylindrical liner ablation experiments at 550 kA

A.M. Steiner; P. C. Campbell; D. A. Yager-Elorriaga; Kyle Robert Cochrane; Thomas R. Mattsson; Nicholas M. Jordan; Ryan D McBride; Y. Y. Lau; Ronald M. Gilgenbach

Presented are the results from the liner ablation experiments conducted at 550 kA on the Michigan Accelerator for Inductive Z-Pinch Experiments. These experiments were performed to evaluate a hypothesis that the electrothermal instability (ETI) is responsible for the seeding of magnetohydrodynamic instabilities and that the cumulative growth of ETI is primarily dependent on the material-specific ratio of critical temperature to melting temperature. This ratio is lower in refractory metals (e.g., tantalum) than in non-refractory metals (e.g., aluminum or titanium). The experimental observations presented herein reveal that the plasma-vacuum interface is remarkably stable in tantalum liner ablations. This stability is particularly evident when contrasted with the observations from aluminum and titanium experiments. These results are important to various programs in pulsed-power-driven plasma physics that depend on liner implosion stability. Examples include the magnetized liner inertial fusion (MagLIF) prog...


Physics of Plasmas | 2018

Evolution of sausage and helical modes in magnetized thin-foil cylindrical liners driven by a Z-pinch

D. A. Yager-Elorriaga; Y. Y. Lau; Peng Zhang; P. C. Campbell; A.M. Steiner; N.M. Jordan; Ryan D McBride; Ronald M. Gilgenbach

In this paper, we present experimental results on axially magnetized (Bz = 0.5 – 2.0 T), thin-foil (400 nm-thick) cylindrical liner-plasmas driven with ∼600 kA by the Michigan Accelerator for Inductive Z-Pinch Experiments, which is a linear transformer driver at the University of Michigan. We show that: (1) the applied axial magnetic field, irrespective of its direction (e.g., parallel or anti-parallel to the flow of current), reduces the instability amplitude for pure magnetohydrodynamic (MHD) modes [defined as modes devoid of the acceleration-driven magneto-Rayleigh-Taylor (MRT) instability]; (2) axially magnetized, imploding liners (where MHD modes couple to MRT) generate m = 1 or m = 2 helical modes that persist from the implosion to the subsequent explosion stage; (3) the merging of instability structures is a mechanism that enables the appearance of an exponential instability growth rate for a longer than expected time-period; and (4) an inverse cascade in both the axial and azimuthal wavenumbers, k...


international conference on plasma science | 2016

Experiments on electrothermal instability as a seed for Magneto-Rayleigh-Taylor instability on accelerating, ablating foils

A.M. Steiner; D. A. Yager-Elorriaga; P. C. Campbell; Sonal Patel; N.M. Jordan; Y.Y. Lau; Ronald M. Gilgenbach

Summary form only given. The electrothermal instability (ETI) arises whenever a current-carrying material has a resistivity that depends on temperature. When resistivity, η, increases with increasing temperature, ETI causes striations to form perpendicular to the direction of current. On pulsed-power-driven, ablating metallic loads, this process can cause sections of the target to ablate earlier than the bulk material, creating a macroscopic surface perturbation on the plasma-vacuum interface. Experiments are underway on the MAIZE 1-MA linear transformer driver at the University of Michigan to study surface perturbations produced by ETI as seeding for the Rayleigh-Taylor (MRT) instability on imploding liner [1] and accelerating foil plasmas [2]. Target foils are fabricated at the Lurie Nanofabrication Facility at UM by depositing ultrathin (200 to 500 nm) coatings of aluminum or titanium on 1.5 μm Chemplex Ultra-Polyester films. Foil thicknesses are chosen to maintain the same mass between shots, and the materials are chosen to provide substantially different values of dη/dt, which impacts the growth rate of the electrothermal instability. Targets are ablated and accelerated by driving a current of 500 to 600 kA on MAIZE, and the accelerated plasmas are imaged using a 12-frame laser imaging system. Images of these plasmas are compared to determine if initial plasma interface perturbations are measurably different on targets of different materials, with the same mass, but different ETI growth rates.


international conference on plasma science | 2016

Experimental investigation of the effects of an axial magnetic field on the magneto Rayleigh-Taylor, sausage and kink instabilities in imploding liner-plasmas

D. A. Yager-Elorriaga; A.M. Steiner; P. C. Campbell; Sonal Patel; N.M. Jordan; Peng Zhang; Y.Y. Lau; Ronald M. Gilgenbach

Summary form only given. Experiments are underway to study the stabilizing effects of an axial magnetic field on the magneto Rayleigh-Taylor (MRT), sausage, and kink instabilities in imploding liner-plasmas at the Michigan Accelerator for Inductive Z-pinch Experiments (MAIZE) facility at the University of Michigan (UM). The liners were fabricated from ultrathin aluminum foils and had thicknesses of 400 nm and 6.55 mm diameters, and were imploded by discharging a current of 600 kA using a 1-MA Linear Transformer Driver1. An independently triggered capacitor bank was used to drive a set of Helmholtz coils in order to generate axial magnetic fields of up to 5 T. The imploding plasma was imaged using a 12-frame laser imaging system, which captured both shadowgraphs and self-emission over a 120-180 ns period. Varying the external magnetic field enabled a controlled study of the stabilizing effects of axial magnetic fields on instability growth in imploding plasmas.


international conference on plasma science | 2016

Mixed double planar wire arrays on Michigan's Ltd generator

V.L. Kantsyrev; A.S. Safronova; V.V. Shlyaptseva; I. Shrestha; Maximillian T. Schmidt-Petersen; A. Stafford; M. Lorance; M.C. Cooper; A.M. Steiner; D. A. Yager-Elorriaga; N.M. Jordan; Ronald M. Gilgenbach; A. S. Chuvatin

Summary form only given. Double Planar Wire Arrays (DPWA), which consist of two parallel rows of wires, have previously demonstrated high radiation efficiency, compact size, and usefulness for various applications in experiments on a University-scale high-impedance Z-pinch generator1. Recently, we successfully performed two experimental campaigns with PWAs on the University of Michigans low-impedance MAIZE (Linear Transformer Driver (LTD)-driven generator, 0.1Ω, 0.5-1 MA, 100-180 ns) in collaboration with the UM team. The details and the analysis of the results of the first experimental campaign can be found in Ref. [2]. The second experimental campaign was focused on studying the implosion and radiative characteristics of DPWAs using a diagnostic set similar to the first campaign, including: filtered X-ray diodes, X-ray spectrographs and pinhole cameras, and a new four-frame shadowgraphy system with 2-ns, 532 nm frequency doubled Nd:YAG laser. Here we present the results of four, mixed-DPWA shots with the load consisting of one plane with 6 Al wires of 10μm diameter and another plane of 6 stainless steel wires of 5.1 μm diameter. The rise-time of the current varies between 175 and 225 ns and shadowgraphy images cover the broad span of time from as early as 116 ns to as late as 304 ns. The shadowgraphy images show ablating and imploding mixed DPWAs that are very different from the images of uniform DPWAs. There is a clearly observed asymmetry of implosions of two wire array planes dependent on the material of each plane, (early time images in particular), captured also by X-ray pinhole images. WADM is used for the analysis of shadowgraphy images. X-ray spectra display both K-shell Al and L-shell Fe features analyzed with non-LTE modeling. Advantages of using mixed wire arrays are discussed.

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N.M. Jordan

University of Michigan

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Sonal Patel

University of Michigan

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Y.Y. Lau

University of Michigan

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