Development of Imploding Liners With Kinetic Energies {Gt} 100 MJ and Their Applications

The Los Alamos program in High Energy Density Physics is developing high performance imploding liners as sources of high energy density environments for experimental physics applications. High performance liners are, for these purposes, liners with high velocity, 100 MJ or more kinetic energy at 20-50 MJ/cm of height. They must have sufficient azimuthal symmetry, axial uniformity and density to perform as high quality impactors on central, cylindrical targets. Scientific applications of such liners are numerous and varied. For example, the properties of materials at extreme energy densities can be assessed in such an experimental environment. The physics of plasmas near solid density can be studied and hydrodynamics experiments at high Mach number (above 5?) in materials that are near solid density and significantly ionized can be conducted. In addition, liners with substantial kinetic energy and good integrity at velocities of one to a few cm/microsec make good implosion drivers for fusion plasmas in the context of magnetized target fusion and MAGO

The plasma formation stage in magnetic compression/magnetized target fusion (MAGO/MTF)

In early 1992, emerging governmental policy in the US and Russia began to encourage ``lab-to-lab`` interactions between the All- Russian Scientific Research Institute of Experimental Physics (VNIIEF) and the Los Alamos National Laboratory (LANL). As nuclear weapons stockpiles and design activities were being reduced, highly qualified scientists become for fundamental scientific research of interest to both nations. VNIIEF and LANL found a common interest in the technology and applications of magnetic flux compression, the technique for converting the chemical energy released by high-explosives into intense electrical pulses and intensely concentrated magnetic energy. Motivated originally to evaluate any possible defense applications of flux compression technology, the two teams worked independently for many years, essentially unaware of the others` accomplishments. But, an early US publication stimulated Soviet work, and the Soviets followed with a report of the achievement of 25 MG. During the cold war, a series of conferences on Megagauss Magnetic Field Generation and Related Topics became a forum for scientific exchange of ideas and accomplishments. Because of relationships established at the Megagauss conferences, VNIIEF and LANL were able to respond quickly to the initiatives of their respective governments. In late 1992, following the Megagauss VI conference, the two institutions agreed to combine resources to perform a series of experiments that essentially could not be performed by each institution independently. Beginning in September, 1993, the two institutions have performed eleven joint experimental campaigns, either at VNIIEF or at LANL. Megagauss- VII has become the first of the series to include papers with joint US and Russian authorship. In this paper, we review the joint LANL/VNIIEF experimental work that has relevance to a relatively unexplored approach to controlled thermonuclear fusion

Conceptual Design for High Mass Imploding Liner Experiments

We have summarized some of the motivation behind high energy liner experiments. We have identified the 100-cm-diameter Disk Explosive-Magnetic Gene promising candidate for powering such experiments and described a phenomenological modeling approach used to understand the limits of DEMG operation. We have explored the liner implosion parameter space that can be addressed by such systems and have selected a design point from which to develop a conceptual experiment. We have applied the phenomenological model to the point design parameters and used 1 D MHD tools to assess the behavior of the liner for parameters at the design point. We have not to optimized the choice of pulse power or liner parameters. We conclude that operating in the velocity range of 10-20 km/s, kinetic energies around 100 MJ are practical with currents approaching 200 MA in the liner. Higher velocities (up to almost 40 km/s) are achieved on the inner surface of a thick liner when the liner collapses to I -cm radius. At 6-cm radius the non- optimized liners explored here are attractive drivers for experiments exploring the compression of magnetized plasmas and at 1 cm they are equally attractive drivers for shock wave experiments in the pressure range of 30-100 Mbar. An experiment based on this design concept is scheduled to be conducted in VNIIEF in August 1996

The VNIIEF/LANL collaboration : ten years of scientific benefit to the Russian Federation and the United States

Since 1992, the All-Russian Scientific Research Institute of Experimental Physics (VNIIEF) and the Los Alamos National Laboratory (LANL), the institutes that designed the first nuclear weapons of the Soviet Union and the United States, respectively, have been working together in fundamental research related to pulsed power technology and high energy density science. Experimental and theoretical work has been performed at Sarov and Los Alamos in areas as diverse as imploding liner physics and applications, fusion plasma formation, isentropic compression of noble gases, and explosively driven high current generation technology, all traditional areas of the Megagauss series of conferences. Recent joint work has focused on the Atlas capacitor bank (23 MJ, 30 MA, 6 ps) now operational at LANL. Even before Atlas became operational, VNIIEF's DEMG capability was used to provide the US with the first available data at ATLAS! upper performance limit (31 MA, 4 ps, 12 km/s velocity for 50 g liner mass). VNIIEF has recently designed and fielded imploding liner experiments on Atlas, with the goal of studying material strength properties by observing unstable perturbation growth. This paper traces the origins of this collaboration and reviews the scientific accomplishments

Computational modeling of ``MAGO`` and other magnetized target fusion concepts

One possible way to obtain a preheated and magnetized plasma suitable for subsequent implosion is the ``MAGO`` concept. The unique MAGO discharge consists of a two chambers, with electrical current flowing in one chamber accelerating plasma flow into an implosion chamber. Up to 4 {times} 10{sup 13} D-T neutrons have been produced in the MAGO discharge. In this paper, we discuss our computational modeling of MAGO. Our objectives are to characterize the plasma, compare with the limited diagnostics available, and to understand the neutron production. We also discuss, briefly, some other possible means for creating a magnetized plasma

MIDOT: A novel probe for monitoring high-current flat transmission lines

This paper was published in the journal Review of Scientific Instruments and the definitive published version is available at http://dx.doi.org/10.1063/1.4971246A novel inductive probe, termed MIDOT, was developed for monitoring high-current flat transmission lines. While being inexpensive the probe does not require calibration, is resistant to both shock waves and temperature variations, and it is easy to manufacture and mount. It generates strong output signals that are relatively easy to interpret and has a detection region limited to a pre-defined part of the transmission line. The theoretical background related to the MIDOT probes, together with their practical implementation in both preliminary experimentation and high-current tests, is also presented in the paper. The novel probe can be used to benchmark existing 2D numerical codes used in calculating the current distribution inside the conductors of a transmission line but can easily detect an early movement of a transmission line component. The probe can also find other applications, such as locating the position of a pulsed current flowing through a thin wire

Megagauss technology and pulsed power applications

This is the final report of a 3-year LDRD project at LANL. Because of recent changes in Russia, there are opportunities to acquire and evaluate technologies for ultrahigh-magnetic-field flux compressors and ultrahigh-energy, ultrahigh-current pulsed-power generators that could provide inexpensive access to various extreme matter conditions and high-energy-density physics regimes. Systems developed by the All-Russian Scientific Research Institute of Experimental Physics (VNIIEF) at Arzamas-16 (Sarova) have the potential of creating new thrusts in several areas of high-magnetic-field and high-energy-density R&D, including high-field and high-temperature superconductivity, Faraday effect, cyclotron resonance, isentropic compression, magneto-optical properties, plasma physics, astrophysics, energy research, etc. Through a formal collaboration supported and encouraged by high-ranking DOE officials and senior laboratory management, we have gained access to unique Russian technology, which substantially exceeds US capabilities in several areas, at a small fraction of the cost which would be incurred in an intensive and lengthy US development program

Analysis of an MCG/fuse/PFS experiment

The Los Alamos PROCYON high-explosive pulsed power (HEPP) implosion system is intended to produce 1 MJ of soft X-radiation for fusion and material studies. The system uses the MK-IX magnetic flux compression generator to drive a ``slow`` opening switch which, upon operation, connects the output of the MK-IX generator to a plasma flow switch, which, in turn, delivers current to a rapidly imploding load. The closing switch isolates the plasma flow switch (PFS) and load from any precursor current which might arise due to the finite impedance of the opening switch during its closed phase. In that experiment, our first test, the MK-IX generated approximately 16 MA and 8.2 MJ, and approximately 9.8 MA and 1.15 MJ were delivered to a fixed inductive load in 8--10 microseconds. Computations performed after the experiment, taking into account experimental variables which could not be accurately predicted prior to the experiment, were in satisfactory agreement with all experimental observations, including a double-peaked dI/dt signal which indicated a particular trajectory of the copper fuse material through density-temperature space. Prompted by our success with a fixed load, a second experiment was performed using the MK-IX/fuse/STS combination to drive a plasma flow switch. The objectives of the experiment were to observe the ability of the fuse/STS combination to drive a plasma flow switch and to evaluate our ability to predict system performance. The details of the experiment, the measurements taken, and the data reduction process have previously been reported. The MK-IX produced approximately 22 MA, and approximately 10 MA was delivered to the PFS, which moved down the coaxial barrel of the assembly in an intact manner in about 8 microseconds. In this paper, we present the results of our computational analysis of the experiment

Future Explosive Pulse-power, Technology For High-energy Plasma Physics Experiments

A variety of high-performance pulse-power systems in the 10 to 20-MJ class have been built in the last ten years or are planned in the next 3--5 years. Such systems, using capacitive energy storage, are employed in particle beam fusion, x-ray effects, x-ray physics, and plasma physics experiments. Advances in the technology of high-energy- density capacitors over the same time period has substantially decreased the cost per joule of the basic capacitor and kept the total parts count in large systems within reason. Overall, the savings in capacitor costs has about balanced the generally increasing system costs keeping the total cost of large, high-performance systems at $1--2 per joule over the period. The next step, to 100-MJ class systems, will profit from the improvements of the last decade, but there seems little reason to project a lowering of the cost per joule. In contrast, there is every reason to expect the continuously growing system costs to outstrip any savings to be realized from improvements in capacitor technology. Over the same period, explosive pulse power systems in the 10 to 20-MJ class have been employed, routinely, in plasma physics experiments. These one- shot systems currently cost about$100 K for the generator and switching and deliver energy to a plasma physics experiment in a few microseconds. Comparing only hardware costs, such systems are competitive with capacitor systems for developmental activities involving 100--200 shots -- but not for repetitive applications involving 1000's of shots. At this rate, explosive systems are competitive systems for applications involving up to 200--500 shots. In this paper, we discuss general concepts for generators and power-conditioning systems appropriate for high-energy applications. We scope two such applications and show how explosive pulse power can address those applications. And we describe one example of an explosively powered generator suitable for 100-MJ operation