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Awe TJ, Shelton KP, Sefkow AB, Lamppa DC, Baker JL, Rovang DC, Robertson GK. Development of a cryogenically cooled platform for the Magnetized Liner Inertial Fusion (MagLIF) Program. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:093515. [PMID: 28964209 DOI: 10.1063/1.4986041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 09/05/2017] [Indexed: 06/07/2023]
Abstract
A cryogenically cooled hardware platform has been developed and commissioned on the Z Facility at Sandia National Laboratories in support of the Magnetized Liner Inertial Fusion (MagLIF) Program. MagLIF is a magneto-inertial fusion concept that employs a magnetically imploded metallic tube (liner) to compress and inertially confine premagnetized and preheated fusion fuel. The fuel is preheated using a ∼2 kJ laser that must pass through a ∼1.5-3.5-μm-thick polyimide "window" at the target's laser entrance hole (LEH). As the terawatt-class laser interacts with the dense window, laser plasma instabilities (LPIs) can develop, which reduce the preheat energy delivered to the fuel, initiate fuel contamination, and degrade target performance. Cryogenically cooled targets increase the parameter space accessible to MagLIF target designs by allowing nearly 10 times thinner windows to be used for any accessible gas density. Thinner LEH windows reduce the deleterious effects of difficult to model LPIs. The Z Facility's cryogenic infrastructure has been significantly altered to enable compatibility with the premagnetization and fuel preheat stages of MagLIF. The MagLIF cryostat brings the liquid helium coolant directly to the target via an electrically resistive conduit. This design maximizes cooling power while allowing rapid diffusion of the axial magnetic field supplied by external Helmholtz-like coils. A variety of techniques have been developed to mitigate the accumulation of ice from vacuum chamber contaminants on the cooled LEH window, as even a few hundred nanometers of ice would impact laser energy coupling to the fuel region. The MagLIF cryostat has demonstrated compatibility with the premagnetization and preheat stages of MagLIF and the ability to cool targets to liquid deuterium temperatures in approximately 5 min.
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Hahn KD, Chandler GA, Ruiz CL, Cooper GW, Gomez MR, Slutz S, Sefkow AB, Sinars DB, Hansen SB, Knapp PF, Schmit PF, Harding E, Jennings CA, Awe TJ, Geissel M, Rovang DC, Torres JA, Bur JA, Cuneo ME, Glebov VY, Harvey-Thompson AJ, Herrman MC, Hess MH, Johns O, Jones B, Lamppa DC, Lash JS, Martin MR, McBride RD, Peterson KJ, Porter JL, Reneker J, Robertson GK, Rochau GA, Savage ME, Smith IC, Styron JD, Vesey RA. Fusion-neutron measurements for magnetized liner inertial fusion experiments on the Z accelerator. ACTA ACUST UNITED AC 2016. [DOI: 10.1088/1742-6596/717/1/012020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Rovang DC, Lamppa DC, Cuneo ME, Owen AC, McKenney J, Johnson DW, Radovich S, Kaye RJ, McBride RD, Alexander CS, Awe TJ, Slutz SA, Sefkow AB, Haill TA, Jones PA, Argo JW, Dalton DG, Robertson GK, Waisman EM, Sinars DB, Meissner J, Milhous M, Nguyen DN, Mielke CH. Pulsed-coil magnet systems for applying uniform 10-30 T fields to centimeter-scale targets on Sandia's Z facility. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:124701. [PMID: 25554308 DOI: 10.1063/1.4902566] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Sandia has successfully integrated the capability to apply uniform, high magnetic fields (10-30 T) to high energy density experiments on the Z facility. This system uses an 8-mF, 15-kV capacitor bank to drive large-bore (5 cm diameter), high-inductance (1-3 mH) multi-turn, multi-layer electromagnets that slowly magnetize the conductive targets used on Z over several milliseconds (time to peak field of 2-7 ms). This system was commissioned in February 2013 and has been used successfully to magnetize more than 30 experiments up to 10 T that have produced exciting and surprising physics results. These experiments used split-magnet topologies to maintain diagnostic lines of sight to the target. We describe the design, integration, and operation of the pulsed coil system into the challenging and harsh environment of the Z Machine. We also describe our plans and designs for achieving fields up to 20 T with a reduced-gap split-magnet configuration, and up to 30 T with a solid magnet configuration in pursuit of the Magnetized Liner Inertial Fusion concept.
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Schmit PF, Knapp PF, Hansen SB, Gomez MR, Hahn KD, Sinars DB, Peterson KJ, Slutz SA, Sefkow AB, Awe TJ, Harding E, Jennings CA, Chandler GA, Cooper GW, Cuneo ME, Geissel M, Harvey-Thompson AJ, Herrmann MC, Hess MH, Johns O, Lamppa DC, Martin MR, McBride RD, Porter JL, Robertson GK, Rochau GA, Rovang DC, Ruiz CL, Savage ME, Smith IC, Stygar WA, Vesey RA. Understanding fuel magnetization and mix using secondary nuclear reactions in magneto-inertial fusion. PHYSICAL REVIEW LETTERS 2014; 113:155004. [PMID: 25375715 DOI: 10.1103/physrevlett.113.155004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Indexed: 06/04/2023]
Abstract
Magnetizing the fuel in inertial confinement fusion relaxes ignition requirements by reducing thermal conductivity and changing the physics of burn product confinement. Diagnosing the level of fuel magnetization during burn is critical to understanding target performance in magneto-inertial fusion (MIF) implosions. In pure deuterium fusion plasma, 1.01 MeV tritons are emitted during deuterium-deuterium fusion and can undergo secondary deuterium-tritium reactions before exiting the fuel. Increasing the fuel magnetization elongates the path lengths through the fuel of some of the tritons, enhancing their probability of reaction. Based on this feature, a method to diagnose fuel magnetization using the ratio of overall deuterium-tritium to deuterium-deuterium neutron yields is developed. Analysis of anisotropies in the secondary neutron energy spectra further constrain the measurement. Secondary reactions also are shown to provide an upper bound for the volumetric fuel-pusher mix in MIF. The analysis is applied to recent MIF experiments [M. R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)] on the Z Pulsed Power Facility, indicating that significant magnetic confinement of charged burn products was achieved and suggesting a relatively low-mix environment. Both of these are essential features of future ignition-scale MIF designs.
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Gomez MR, Slutz SA, Sefkow AB, Sinars DB, Hahn KD, Hansen SB, Harding EC, Knapp PF, Schmit PF, Jennings CA, Awe TJ, Geissel M, Rovang DC, Chandler GA, Cooper GW, Cuneo ME, Harvey-Thompson AJ, Herrmann MC, Hess MH, Johns O, Lamppa DC, Martin MR, McBride RD, Peterson KJ, Porter JL, Robertson GK, Rochau GA, Ruiz CL, Savage ME, Smith IC, Stygar WA, Vesey RA. Experimental demonstration of fusion-relevant conditions in magnetized liner inertial fusion. PHYSICAL REVIEW LETTERS 2014; 113:155003. [PMID: 25375714 DOI: 10.1103/physrevlett.113.155003] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Indexed: 06/04/2023]
Abstract
This Letter presents results from the first fully integrated experiments testing the magnetized liner inertial fusion concept [S. A. Slutz et al., Phys. Plasmas 17, 056303 (2010)], in which a cylinder of deuterium gas with a preimposed 10 Taxial magnetic field is heated by Z beamlet, a 2.5 kJ, 1 TW laser, and magnetically imploded by a 19 MA, 100 ns rise time current on the Z facility. Despite a predicted peak implosion velocity of only 70 km = s, the fuel reaches a stagnation temperature of approximately 3 keV, with T(e) ≈ T(i), and produces up to 2 x 10(12) thermonuclear deuterium-deuterium neutrons. X-ray emission indicates a hot fuel region with full width at half maximum ranging from 60 to 120 μm over a 6 mm height and lasting approximately 2 ns. Greater than 10(10) secondary deuterium-tritium neutrons were observed, indicating significant fuel magnetization given that the estimated radial areal density of the plasma is only 2 mg = cm(2).
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Awe TJ, McBride RD, Jennings CA, Lamppa DC, Martin MR, Rovang DC, Slutz SA, Cuneo ME, Owen AC, Sinars DB, Tomlinson K, Gomez MR, Hansen SB, Herrmann MC, McKenney JL, Nakhleh C, Robertson GK, Rochau GA, Savage ME, Schroen DG, Stygar WA. Observations of modified three-dimensional instability structure for imploding z-pinch liners that are premagnetized with an axial field. PHYSICAL REVIEW LETTERS 2013; 111:235005. [PMID: 24476283 DOI: 10.1103/physrevlett.111.235005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Indexed: 06/03/2023]
Abstract
Novel experimental data are reported that reveal helical instability formation on imploding z-pinch liners that are premagnetized with an axial field. Such instabilities differ dramatically from the mostly azimuthally symmetric instabilities that form on unmagnetized liners. The helical structure persists at nearly constant pitch as the liner implodes. This is surprising since, at the liner surface, the azimuthal drive field presumably dwarfs the axial field for all but the earliest stages of the experiment. These fundamentally 3D results provide a unique and challenging test for 3D-magnetohydrodynamics simulations.
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Bennett GR, Cuneo ME, Vesey RA, Porter JL, Adams RG, Aragon RA, Caird JA, Landen OL, Rambo PK, Rovang DC, Ruggles LE, Simpson WW, Smith IC, Wenger DF. Symmetric inertial-confinement-fusion-capsule implosions in a double-z-pinch-driven hohlraum. PHYSICAL REVIEW LETTERS 2002; 89:245002. [PMID: 12484951 DOI: 10.1103/physrevlett.89.245002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2002] [Indexed: 05/24/2023]
Abstract
An inertial-confinement-fusion (ICF) concept using two 60-MA Z pinches to drive a cylindrical hohlraum to 220 eV has been recently proposed. The first capsule implosions relevant to this concept have been performed at the same physical scale with a lower 20-MA current, yielding a 70+/-5 eV capsule drive. The capsule shell shape implies a polar radiation symmetry, the first high-accuracy measurement of this type in a pulsed-power-driven ICF configuration, within a factor of 1.6-4 of that required for scaling to ignition. The convergence ratio of 14-21 is to date the highest in any pulsed-power ICF system.
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