A zero-dimensional transport model for field-reversed configurations

Rej, D. J.; Tuszewski, M.

doi:10.1063/1.864783

Cited by 48 publications

(43 citation statements)

References 16 publications

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“…With the improved energy confinement at larger s, the radiated power has become a significant loss channel (see Table I). The radiated power during equilibrium was consistent with line radiation from the same small fraction (0.04%) of silicon impurity observed in previous FRC experiments performed in quartz vacuum chambers [14]. The Z e ff determined from doping experiments on LSX was typically 1.3, with oxygen at about 0.3% being the most abundant impurity.…”

supporting

confidence: 65%

Confinement and stability of plasmas in a field-reversed configuration

et al. 1992

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Experiments have been conducted on the LSX device where plasmas confined in a field-reversed magnetic geometry have exhibited record energy, particle, and configuration lifetimes. The scaling from previous smaller devices showed a very positive confinement scaling with J, the number of ion gyroradii inside the field-reversed configuration. These plasmas were observed to have gross stability to global loworder modes such as the internal tilt. The growth of tilt instabilities was not observed during the equilibrium decay of plasmas up to s~8.PACS numbers: 52.55.Pi A new experimental device (LSX) has been constructed to explore the confinement and stability of magnetically confined plasma known as a field-reversed configuration (FRC). An FRC has a compact toroidal confinement geometry where induced toroidal diamagnetic currents generate the confining poloidal field [1]. Since the toroidal field is typically small inside the FRC, the configuration has an intrinsically high plasma p (the magnetic field vanishes at the plasma core). This feature together with the simple cylindrical geometry, the natural diverter nature of the external magnetic field, and the ease of translation [2] give the FRC unique advantages as a fusion reactor-particularly for advanced fuels [3].From a theoretical point of view, the key issue has been the gross stability of the configuration. For several years it has been known that the FRC equilibrium, as a result of the unfavorable curvature of the closed field lines (see Fig. 1), is unstable in the magnetohydrodynamic (MHD) limit. In particular, the FRC is unstable to the internal tilt instability [4]. This global mode consists of a rotation of the FRC orthogonal to the symmetry axis with only a small distortion to the separatrix shape, and thus cannot be suppressed by the application of an external magnetic field. The mode has a growth rate that would annihilate the configuration on the shortest possible MHD time FIG. 1. Schematic of the LSX experiment. Equilibrium flux contours are shown from a 2D numerical calculation for an FRC in LSX. scale, the time for an Alfven wave to propagate the half length of the FRC.Stability for many Alfven transit times has been observed in several FRC experiments [1,5]. The FRCs formed in these experiments, however, had a strong kinetic particle component. This component can be characterized by the parameter s, the average number of ion gyroradii between the null and separatrix of the FRC, and s was typically 2 or less. It was shown that for s < 2, kinetic effects significantly increased the MHD tilt growth time [6] to as long as the FRC configuration lifetimes obtained at that time. Subsequent experiments on the TRX device, however, indicated stability to the tilt at moderate s (2 to 4) for many kinetically increased tilt growth times [5]. The confinement did not improve with increasing s as had been observed in previous low-j, kinetic-regime experiments. It was not determined what limited confinement; however, the equilibria produced in these large-.? experim...

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confidence: 65%

Confinement and stability of plasmas in a field-reversed configuration

et al. 1992

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“…Most of the data indicate P rad Ͻ 1% of the total loss. This is in contrast to the typical result of Ͼ5% obtained on lowdensity experiments, 10 including STP-L 16 and FRX-C. 17,4 Using the same zero-dimensional model that was utilized for FRX-L, radiation was found to represent 10%-40% of the total losses for typical shots on LSX. 5 Shot 4520 at 8 Microseconds Figure 7 shows the peak radiation for FRX-L shots compared to the total power loss.…”

Section: A Comparison Of Radiation With Other Loss Mechanismsmentioning

confidence: 79%

Power balance in a high-density field reversed configuration plasma

et al. 2008

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A global power balance analysis has been performed for the Field Reversed Experiment with Liner high density (>5×1022m−3) field reversed configuration (FRC) plasma. The analysis was based on a zero-dimensional power balance model [D. J. Rey and M. Tuszewski, Phys. Fluids 27, 1514 (1984)]. The key findings are as follows. First, the percentage of radiative losses relative to total loss is an order of magnitude lower than previous lower density FRC experiments. Second, Ohmic heating was found to correlate with the poloidal flux trapping at FRC formation, suggesting that poloidal flux dissipation is primarily responsible for plasma heating. Third, high density FRCs analyzed in this work reinforce the low-density adiabatic scaling, which shows that particle confinement time and flux confinement time are approximately equal.

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“…This in turn sets the liner size, which sets the plasma size and starting plasma density and pressure needed. A zero-D model for the cylindrical liner compression of the FRC, 22,23 and FRC semiempirical formation models, 24 were then used to determine required fields, which in turn drove the design of the coils and the electrical circuit. Table I summarizes the design parameters for the experiment and compares them to our actual parameters ͑see the following sections for more details on how the latter were obtained͒.…”

Section: Frx-l Experimental Descriptionmentioning

confidence: 99%

FRX-L: A field-reversed configuration plasma injector for magnetized target fusion

Taccetti

Intrator

Wurden

et al. 2003

Review of Scientific Instruments

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We describe the experiment and technology leading to a target plasma for the magnetized target fusion research effort, an approach to fusion wherein a plasma with embedded magnetic fields is formed and subsequently adiabatically compressed to fusion conditions. The target plasmas under consideration, field-reversed configurations ͑FRCs͒, have the required closed-field-line topology and are translatable and compressible. Our goal is to form high-density (10 17 cm Ϫ3 ) FRCs on the field-reversed experiment-liner ͑FRX-L͒ device, inside a 36 cm long, 6.2 cm radius theta coil, with 5 T peak magnetic field and an azimuthal electric field as high as 1 kV/cm. FRCs have been formed with an equilibrium density n e Ϸ(1 to 2)ϫ10 16 cm Ϫ3 , T e ϩT i Ϸ250 eV, and excluded flux Ϸ2 to 3 mWb.

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A zero-dimensional transport model for field-reversed configurations

Cited by 48 publications

References 16 publications

Confinement and stability of plasmas in a field-reversed configuration

Confinement and stability of plasmas in a field-reversed configuration

Power balance in a high-density field reversed configuration plasma

FRX-L: A field-reversed configuration plasma injector for magnetized target fusion

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