Production of Very High Magnetic Fields by Implosion

Fowler, C.M.; Garn, W.B.; Caird, R.S.

doi:10.1063/1.1735633

Cited by 237 publications

(54 citation statements)

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“…[5]) and the external fields that can be generated by coils. Magnetic-flux compression [6] is a viable path to generating tens of MG magnetic fields with adequate size compression of a metal liner driven by high explosives [7,8] or by pulsed power. The latter approach has been pursued by the Z-pinch [9] communities.…”

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confidence: 99%

Laser-Driven Magnetic-Flux Compression in High-Energy-Density Plasmas

et al. 2009

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The demonstration of magnetic field compression to many tens of megagauss in cylindrical implosions of inertial confinement fusion targets is reported for the first time. The OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] was used to implode cylindrical CH targets filled with deuterium gas and seeded with a strong external field (>50 kG) from a specially developed magnetic pulse generator. This seed field was trapped (frozen) in the shock-heated gas fill and compressed by the imploding shell at a high implosion velocity, minimizing the effect of resistive flux diffusion. The magnetic fields in the compressed core were probed via proton deflectrometry using the fusion products from an imploding D 3 He target. Line-averaged magnetic fields between 30 and 40 MG were observed. In the magnetic fusion energy (MFE) concept, a strong magnetic field confines the plasma and reduces the electron thermal conduction to the vessel wall [1]. The magnetic pressure of typical $0:1-MG fields is higher than the total energy density of the plasma (with ¼ 2 0 p=B 2 < 1). MFE plasmas are fully magnetized and characterized by a Hall parameter ! ce > 1 since the modest gyrofrequency ! ce is matched by long collision times . In contrast, typical inertial confinement fusion (ICF) plasmas have collision frequencies higher by 10 to 12 orders of magnitude because of their extreme density. In such systems, thermal conduction losses are a major factor in the energy balance of an implosion. While it can be more difficult, magnetizing the hot spot in ICF implosions can lead to improved gains and to a reduction of the energy required for ignition. A similar approach is used in the magnetized target fusion concept [2], where the fusion burn requires relatively low-implosion velocities, provided there is an adequate magnetic thermal insulation. In ICF implosions, lower implosion velocities lead to higher gains [3]. However, tens of MG are needed to achieve ! ce $ 1 in the hot spot of a typical, direct drive DT ignition target [4] with hot-spot density of $30 g=cc and a temperature of $7 keV. Such a field is higher than both the self-generated magnetic fields (see Ref. [5]) and the external fields that can be generated by coils. Magnetic-flux compression [6] is a viable path to generating tens of MG magnetic fields with adequate size compression of a metal liner driven by high explosives [7,8] or by pulsed power. The latter approach has been pursued by the Z-pinch [9] communities. The results from the first experiments on a new approach that provides very effective flux compression are reported here. The field is compressed by the ablative pressure exerted on an imploding ICF capsule by the driving laser [10]. This approach was proposed in the 1980s [11] as a way to achieve record compressed fields with possible applications for fusion [12] but no laser experiments were performed. There are numerous advantages to this approach as the implosion velocity is high (a few 10 7 cm=s) and the hot plasma is an effective conductor that tra...

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confidence: 99%

Laser-Driven Magnetic-Flux Compression in High-Energy-Density Plasmas

et al. 2009

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“…The method of magnetic flux compression by cylindrical explosive implosion is a unique technique of ultrahigh magnetic field production [1][2][3][4][5]. The principle of this method is that of the conservation of magnetic flux enclosed within the boundary of a perfect conductor.…”

Section: Introductionmentioning

confidence: 99%

Experiments of cylindrical isentropic compression by ultrahigh magnetic field

Zhou

Zhang

et al. 2015

EPJ Web of Conferences

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Abstract. The high Explosive Magnetic Flux Implosion Compression Generator (EMFICG) is a kind of unique high energy density dynamic technique with characters like ultrahigh pressure and low temperature rising and could be suitable as a tool of cylindrical isentropic compression. The Institute of Fluid Physics, Chinese Academy of Engineering Physics (IFP, CAEP) have developed EMFICG technique and realized cylindrical isentropic compression. In the experiments, a seed magnetic field of 5-6 Tesla were built first and compressed by a stainless steel liner which is driven by high explosive. The inner free surface velocity of sample was measured by PDV. The isentropic compression of a copper sample was verified and the isentropic pressure is over 100 GPa. The cylindrical isentropic compression process has been numerical simulated by 1D MHD code and the simulation results were compared with the experiments. Compared with the transitional X-ray flash radiograph measurement, this method will probably promote the data accuracy.

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“…Invented by Andre Sakharov 1,2 (and independently by several others including Shearer 3 and Fowler 4 ) in the 1950's, these devices have been used to reach energy and current outputs unobtainable by conventional capacitor bank systems. These systems come in many forms, ranging from small flat plates to large disk and coaxial systems [5][6][7][8] .…”

Section: Introductionmentioning

confidence: 99%

The advanced helical generator

Reisman

Javedani

Ellsworth

et al. 2010

Review of Scientific Instruments

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A high explosive pulsed power (HEPP) generator called the Advanced Helical Generator (AHG) has been designed, built, and successfully tested. The AHG incorporates design principles of voltage and current management to obtain a high current and energy gain.Its design was facilitated by the use of modern modeling tools as well as high precision manufacture. The result was a first-shot success. The AHG delivered 16 Mega-Amperes of current and 11 Mega-Joules of energy to a quasi-static 80 nH inductive load. A current gain of 154 times was obtained with a peak exponential rise time of 20 μs. We will describe in detail the design and testing of the AHG.

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Production of Very High Magnetic Fields by Implosion

Cited by 237 publications

References 0 publications

Laser-Driven Magnetic-Flux Compression in High-Energy-Density Plasmas

Laser-Driven Magnetic-Flux Compression in High-Energy-Density Plasmas

Experiments of cylindrical isentropic compression by ultrahigh magnetic field

The advanced helical generator

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