Experimental Observations on the Structure of Collisionless Shock Waves in a Magnetized Plasma

Paul, J. W. M.; Holmes, L. S.; Parkinson, M. J.; Sheffield, John

doi:10.1038/208133a0

Cited by 123 publications

(34 citation statements)

References 10 publications

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“…The plasma flux and velocity increased with the range of peak discharge current. If the plasma flux and velocity increase linearly with peak discharge current, the plasma flux and the velocity can reach 10003-p. 3 40 A/cm 2 and 500 km/s respectively at the discharge current of 100 kA. However, this is not assured extrapolation because higher discharge current tends to induce plasma instability strongly.…”

Section: Resultsmentioning

confidence: 97%

“…Taper angle is 8.3 deg. Argon gas is filled in the capillary, where initial mass density 0 = 2.4 × 10 −6 g/cm 3 . The Faraday cup is located at 40 cm from end of the capillary.…”

Section: Experimental Apparatusmentioning

confidence: 99%

“…Lasers [2], z-pinch discharges [3] and arc channels [4] have been conventionally used to drive the highspeed flow. However, in case of hydro-dynamical acceleration, heating up and expansion processes are inevitable for making the flow, in which the density and the flow speed are gas-dynamically correlated.…”

Section: Concept and Advantagesmentioning

confidence: 99%

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Formation of dense, electromagnetically accelerated plasma for laboratory astrophysics

Adachi

Nakajima

Kawamura

et al. 2013

EPJ Web of Conferences

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Abstract. We proposed tapered pinch discharge as a measure to conduct laboratory astrophysics experiments. Basic behaviors of the plasma have been characterized using a prototype device. Results show that the plasma flux and velocity depend on initial gas density, discharge current and taper geometry. Those behaviors can be illustrated with a simple model considering the pinching dynamics of the current sheet based on a 1 dimensional (1-D) equation of motion. Achievable value of the tapered pinch plasma is estimated and compared with required plasma parameters based on scaling parameters for laboratory astrophysics.

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Section: Resultsmentioning

confidence: 97%

“…Taper angle is 8.3 deg. Argon gas is filled in the capillary, where initial mass density 0 = 2.4 × 10 −6 g/cm 3 . The Faraday cup is located at 40 cm from end of the capillary.…”

Section: Experimental Apparatusmentioning

confidence: 99%

See 1 more Smart Citation

Formation of dense, electromagnetically accelerated plasma for laboratory astrophysics

Adachi

Nakajima

Kawamura

et al. 2013

EPJ Web of Conferences

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“…Nevertheless, some limiting cases have not only been predicted theoretically (Sagdeev, 1964;Galeev and Sagdeev, 1966;Tidman, 1967) but also found in laboratory (Iskoldsky et al, 1964;Zagorodnikov et al, 1964;Paul et al, 1965;Alikhanov et al 1968;Wong & Means, 1971;Volkov et al, 1974) and space experiments (Moreno et al, 1966;Olbert, 1968;Bame et al, 1979;Vaisberg et al, 1982). The comparison of the laboratory and satellite experiments has revealed a close agreement between them for certain collisionless shock fronts (V.G.…”

Section: Shock Wave Problem and Its Related Lawmentioning

confidence: 99%

Solar Wind Laws Valid for any Phase of a Solar Cycle

Еселевич¹

2012

Exploring the Solar Wind

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“…The formation of dense, high-speed plasma is essential for those applications and the investigation of related plasma phenomena. Devices such as a laser [2], z-pinch [3], or arc channel [4] are conventionally used to drive the highspeed flow. However, dense, high-speed flow is difficult to form by hydrodynamic acceleration because of rarefaction waves accompanying the acceleration process.…”

mentioning

confidence: 99%

Formation Mechanism of Dense High-Speed Plasma Flow in Tapered Capillary Discharge

Adachi

Nakajima

Kawamura

et al. 2011

Plasma and Fusion Research

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We propose a new type of plasma source using a pinch discharge in a tapered capillary, which generates a dense moving plasma by electromagnetic compression and acceleration. The axial velocity and flux of the moving plasma are controllable and can be maximized by adjusting the taper angle. The behavior can be illustrated with a simple model considering the pinching dynamics of the current sheet. [4] are conventionally used to drive the highspeed flow. However, dense, high-speed flow is difficult to form by hydrodynamic acceleration because of rarefaction waves accompanying the acceleration process. Also, a strong correlation among velocity, temperature, and density in hydrodynamically accelerated plasma is undesirable for almost all applications, especially parametric studies in astrophysics. Pinching plasmas in a plasma focus system can form high-energy density, high-speed plasmas [1,5]. Electromagnetic acceleration can avoid the need to heat the plasma in order to increase the axial velocity. Therefore, a dense plasma can be formed by a compression process in a z-pinch system. However, the plasma parameters are difficult to control owing to nonuniform gas discharge.We propose a new type of plasma device for the formation of dense high-speed plasma flow, in which the plasma parameters can be controlled by manipulating the operating conditions. Figure 1 shows a schematic diagram of the proposed scheme. The current sheet in a tapered capillary radially compresses and axially accelerates the plasma. Using this scheme, an argon plasma was accelerated to 700 km/s by a tapered pinch discharge with a fast pulse power generator, which drove a load current of 80 kA with a pulse width of 70 ns [6]. The electromagnetic energy is converted to the thermal energy and axial kinetic energy of the moving plasma. In this device, the geometry of the tapered capillary is expected to play an important role in distributing of the energy. We intend to clarify the relationships between the experimental conditions (i.e., author's e-mail: adachi.k.ad@m.titech.ac.jp initial gas density in the capillary, discharge current waveform, and capillary geometry) and the plasma parameters (i.e., axial velocity, flux, and temperature) of the taperpinched plasma.A tapered capillary was filled quasi-statically with a well-defined density of argon gas by differential pumping and pre-ionized by an RC (∼400 µs) discharge of 15 A for moderating the nonuniformity of the discharge. An LCinversion-type pulse generator with a capacitance of 12 nF was installed for driving the main discharge circuit, as shown in Fig. 2. The length and inlet radius of the tapered capillary were 10 mm and 0.5 mm, respectively. The moving plasma flux was measured as a function of the gas density and taper angle by a Faraday cup (FC) located 22 cm from the capillary's aperture. The main discharge current and voltage were measured by a Rogowski coil and a highvoltage probe at the end of capillary, respectively. Figure 3 shows typical waveforms of the discharge current, voltage, ...

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Experimental Observations on the Structure of Collisionless Shock Waves in a Magnetized Plasma

Cited by 123 publications

References 10 publications

Formation of dense, electromagnetically accelerated plasma for laboratory astrophysics

Formation of dense, electromagnetically accelerated plasma for laboratory astrophysics

Solar Wind Laws Valid for any Phase of a Solar Cycle

Formation Mechanism of Dense High-Speed Plasma Flow in Tapered Capillary Discharge

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