Confinement analyses of the high-density field-reversed configuration plasma in the field-reversed configuration experiment with a liner

Zhang, Shouyin; Intrator, T.; Wurden, G. A.; Waganaar, W. J.; Taccetti, J. M.; Renneke, R.; Grabowski, C.; Ruden, E.L.

doi:10.1063/1.1899648

Cited by 16 publications

(13 citation statements)

References 35 publications

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“…The representative target is therefore = 0.008 g / cm 3 , or n = / m =2ϫ 10 21 cm −3 . For a FRC target it may be technically challenging to increase R further by increasing the target density since the initial precompressed target number density n 0 = n / C t 3 =2ϫ 10 18 cm −3 is already quite high in comparison with densities ϳ6 ϫ 10 16 cm −3 realized in current FRC formation experiments, 14,15 and would require an external magnetic field of ϳ10 T or more depending on the elongation of the FRC. It is not known whether 30ϫ higher densities could be attainable, or possibly realized in other magnetized plasmas with quasispherical geometries suitable for the PJMTF scheme.…”

Section: Ignition Criterion and Representative Target Parametersmentioning

confidence: 98%

On the efficacy of imploding plasma liners for magnetized fusion target compression

Parks

2008

Physics of Plasmas

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A new theoretical model is formulated to study the idea of merging a spherical array of converging plasma jets to form a “plasma liner” that further converges to compress a magnetized plasma target to fusion conditions [Y. C. F. Thio et al., “Magnetized target fusion in a spheroidal geometry with standoff drivers,” Current Trends in International Fusion Research II, edited by E. Panarella (National Research Council Canada, Ottawa, Canada, 1999)]. For a spherically imploding plasma liner shell with high initial Mach number (M=liner speed/sound speed) the rise in liner density with decreasing radius r goes as ρ∼1∕r2, for any constant adiabatic index γ=dlnp∕dlnρ. Accordingly, spherical convergence amplifies the ram pressure of the liner on target by the factor A∼C2, indicating strong coupling to its radial convergence C=rm∕R, where rm(R)=jet merging radius (compressed target radius), and A=compressed target pressure/initial liner ram pressure. Deuterium-tritium (DT) plasma liners with initial velocity ∼100km∕s and γ=5∕3, need to be hypersonic M∼60 and thus cold in order to realize values of A∼104 necessary for target ignition. For optically thick DT liners, T<2eV, n>1019–1020cm−3, blackbody radiative cooling is appreciable and may counteract compressional heating during the later stages of the implosion. The fluid then behaves as if the adiabatic index were depressed below 5∕3, which in turn means that the same amplification A=1.6×104 can be accomplished with a reduced initial Mach number M≈12.7(γ−0.3)4.86, valid in the range (10<M<60). Analytical calculations indicate that the hydrodynamic efficiency for plasma liners assembled by current and anticipated plasma jets is <4%. A new similarity model for fusion α-particle heating of the collapsed liner indicates that “spark” ignition of the DT liner fuel does not appear to be possible for magnetized fusion targets with typical threshold values of areal density ρR<0.02gcm−2.

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Section: Ignition Criterion and Representative Target Parametersmentioning

confidence: 98%

On the efficacy of imploding plasma liners for magnetized fusion target compression

Parks

2008

Physics of Plasmas

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“…The plasma in the formation stage is simulated with an immobile conductive cylinder of the dimensions typical for FRX-L plasmas. 2,[4][5][6] In this presentation, we use the labels: "pl" for plasma, "FEP" for passive shields, and "coil" for driven coils. The length of the plasma cylinder was chosen equal to that of the coil, L pl = L -coil = 45.23 cm, and the radius equal to the separatrix ͑excluded flux͒ radius, 2,4-6,33,34 R pl = 2.8 cm.…”

Section: Eddy-current Codementioning

confidence: 99%

“…This corresponds to lift off time, when the field strengths on the axis, r = 0, and at the nearest surface of the conical coil, r = 6.2 cm, are almost equal, and the closed flux surfaces characteristic of the FRC are formed. 2,4,7,13 Poloidal field profiles, B z ͑z͒, are plotted for 32 radial positions, r = 0 -6.2 cm with the step of 0.2 cm, at the lift off time t = 0.75 s ͓Fig. 4͑e͔͒.…”

Section: B Formation Of Frc Magnetic Structurementioning

confidence: 99%

“…1 The existing field reversed experiment liner ͑FRX-L͒ uses a field reversed -pinch to form field reversed configuration ͑FRC͒ plasmas, which will be compressed by an imploding aluminum flux conserver ͑liner͒ to achieve fusion relevant conditions. [2][3][4][5][6][7][8][9][10][11][12] FRC formation for MTF requires ͑1͒ substantial trapping of initial magnetic flux to achieve high pressures and Ohmic heating, with FRC lifetimes sufficient for ͑2͒ FRC translation into a compression region. For these reasons, integrated magnetic system design and FRC formation modeling must include driven magnetic coils, passive magnetic shields, and the plasma in the formation region.…”

Section: Magnetic Design Calculation and Frc Formation Modeling For Tmentioning

confidence: 99%

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Magnetic design calculation and FRC formation modeling for the field reversed experiment liner

Dorf

Intrator

Awe

et al. 2008

Journal of Applied Physics

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Integrated magnetic modeling and design are important to meet the requirements for (1) formation, (2) translation, and (3) compression of a field reversed configuration (FRC) for magnetized target fusion. Off-the-shelf solutions do not exist for many generic design issues. A predictive capability for time-dependent magnetic diffusion in realistically complicated geometry is essential in designing the experiment. An eddy-current code was developed and used to compute the mutual inductances between driven magnetic coils and passive magnetic shields (flux excluder plates) to calculate the self-consistent axisymmetric magnetic fields during the first two stages. The plasma in the formation stage was modeled as an immobile solid cylinder with selectable constant resistivity and magnetic flux that was free to readjust itself. It was concluded that (1) use of experimentally obtained anomalously large plasma resistivity in magnetic diffusion simulations is sufficient to predict magnetic reconnection and FRC formation, (2) comparison of predicted and experimentally observed timescales for FRC Ohmic decay shows good agreement, and (3) for the typical range of resistivities, the magnetic null radius decay rate scales linearly with resistivity. The last result can be used to predict the rate of change in magnetic flux outside of the separatrix (equal to the back-emf loop voltage), and thus estimate a minimum θ-coil loop voltage required to form an FRC.

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“…The FRC experiments at the University of Washington focus on the translation of theta-pinch formed plasmas [32], and the formation and sustainment of plasmas with the use of RMF (rotating magnetic field) techniques [33][34][35]. The MTF (magnetic target fusion) experiment at Los Alamos focuses on formation of FRC plasmas by traditional theta-pinch techniques, aimed at providing a high-density plasma target for further compression [36,37]. The SSX experiment at Swarthmore College [22] and the TS-3/4 experiments at the University of Tokyo [14][15][16][17][18][19][20][21] continue to focus on the innovative formation and stability of FRC plasmas with relatively small sizes and without a neutral beam injection system.…”

Section: Introductionmentioning

confidence: 99%

A Self-Organized Plasma with Induction, Reconnection, and Injection Techniques: the SPIRIT Concept for Field Reversed Configuration Research

Gerhardt

Белова

et al. 2007

Plasma and Fusion Research

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A comprehensive research concept, known as SPIRIT, is described for the investigation of the formation, stability, and sustainment of oblate field reversed configurations (FRCs). This concept, whose name stands for Self-organized Plasma with Induction, Reconnection, and Injection Techniques (SPIRIT), allows for the study of FRC stability properties on time scales much longer than the energy confinement time. Counter-helicity merging of inductively formed spheromaks is utilized to form large-flux FRCs. These FRCs are sustained by neutral beam injection with the initial aid of compact ohmic solenoids. Stability to n = 1 tilt/shift modes is provided by plasma shaping and conducting shells. Stability to n ≥ 2 co-interchange modes is achieved by a distribution of highenergy non-thermal ions provided by the neutral beam. The combination of plasma shaping, conducting shells, current sustainment, and the non-thermal beam component are expected to lead to a configuration with stability to all global MHD modes, a regime recently discovered through hybrid-MHD simulation using the HYM code. An experimental test of the concept, utilizing the existing Magnetic Reconnection Experiment (MRX) facility, is described. Initial experiments in MRX have confirmed the viability of the SPIRIT concept, and calculations indicate that the confinement of high-energy ions in MRX should be sufficient to test the SPIRIT concept.

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Confinement analyses of the high-density field-reversed configuration plasma in the field-reversed configuration experiment with a liner

Cited by 16 publications

References 35 publications

On the efficacy of imploding plasma liners for magnetized fusion target compression

On the efficacy of imploding plasma liners for magnetized fusion target compression

Magnetic design calculation and FRC formation modeling for the field reversed experiment liner

A Self-Organized Plasma with Induction, Reconnection, and Injection Techniques: the SPIRIT Concept for Field Reversed Configuration Research

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