RFP confinement physics studied on the Extrap-T1 device

Mazur, S.; Nordlund, P.; Brzozowski, J.; Drake, James R.; Zastrow, K.‐D.

doi:10.1088/0029-5515/34/3/i10

Cited by 23 publications

(22 citation statements)

References 27 publications

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“…The experimental scalings T ∝ I/n 0.5 (∝ (I/N ) 0.5 I 0.5 ) and β θ ∝ I −0.93 n 0.46 ∝ (I/N ) −0.46 I −0.47 were recently found on the EXTRAP T2 RFP [10]; see Fig. confinement experiments on the smaller EXTRAP T1 RFP gave the dependence β θ ∝ I −0.67 n 0.16 ∝ I −0.51 [11]. The unfavourable β θ scaling with I is due to ohmic heating becoming less effective as compared with parallel heat conduction.The rise in temperature does not compensate for the rise of poloidal flux as the current is increased, thus β θ decreases.…”

Section: Poloidal Beta Scalingmentioning

confidence: 63%

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Numerical studies of confinement scaling in the conventional reversed field pinch

Scheffel

Schnack

2000

Nucl. Fusion

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Scaling laws for reversed field pinch (RFP) confinement parameters versus plasma current and density are found from computer simulations. The RFP dynamics at high Lundquist numbers approaching 106 is studied using a high resolution, 3-D, resistive MHD numerical code. Optimum plasma conditions are attained by assuming that the transport coefficients are classical, and by ignoring radiation losses and resistive wall effects. Anomalous global transport results from classical parallel heat conduction along stochastic field lines in the plasma core. The pinch parameter is Θ = 1.8 and the aspect ratio is R/a = 1.25. Poloidal beta is found to scale as βθ ∝ (I/N)-0.40I-0.40 and energy confinement time as τE ∝ (I/N)0.34I0.34. On-axis temperature scales as T(0) ∝ (I/N)0.56I0.56. Experimental results from T2, RFX and MST agree well with the above numerical results and also with the obtained magnetic fluctuation scaling ∝ S-0.14, where S is the Lundquist number. Thus stochastic core field lines appear to persist also at higher, reactor relevant currents and temperatures in the conventional RFP, indicating the need to further pursue confinement enhancement techniques.

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Section: Poloidal Beta Scalingmentioning

confidence: 63%

“…The relation (11) can also be applied to an ohmically heated tokamak plasma. In this case f G has a neoclassical correction ≈[1 − (r/R) 0.5 ] −2 , weighted with current over the plasma cross-section, yielding a numerical value of similar magnitude to that of the RFP.…”

Section: Energy Confinement Scalingmentioning

confidence: 99%

Numerical studies of confinement scaling in the conventional reversed field pinch

Scheffel

Schnack

2000

Nucl. Fusion

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“…Earlier confinement experiments on the smaller Extrap T1 RFP gave the dependence b u~I 20.67 n 0.16~I 20.51 [11]. We now consider the scaling of t E , the energy confinement time.…”

Section: D Schnackmentioning

confidence: 93%

Confinement Scaling Laws for the Conventional Reversed-Field Pinch

Scheffel

Schnack

2000

Phys. Rev. Lett.

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A series of high resolution, 3D, resistive MHD numerical simulations of the reversed-field pinch are performed to obtain scaling laws for poloidal beta and energy confinement at Lundquist numbers approaching 10(6). Optimum plasma conditions are attained by taking the transport coefficients to be classical, and ignoring radiation losses and resistive wall effects. We find that poloidal beta scales as beta(straight theta) approximately I-0.40 and that the energy confinement time scales as tau(E) approximately I0.34 for fixed I/N, with aspect ratio R/a = 1.25.

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“…6, where D is plotted versus ⌬L for the cases R/aϭ8. 8 lated at a fixed time, for a different number of poloidal revolutions. As seen from this figure, for ⌬LϽ20, D increases with ⌬L, with a approximately constant ratio of D between the two cases.…”

Section: Shown Inmentioning

confidence: 99%

Numerical studies of the reversed-field pinch at high aspect ratio

Sätherblom

Drake

1998

Physics of Plasmas

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Density fluctuation measurements by far-forward collective scattering in the MST reversed-field pincha) Rev. Sci. Instrum. 83, 10E302 (2012);The reversed field pinch ͑RFP͒ configuration at an aspect ratio of 8.8 is studied numerically by means of the three-dimensional magnetohydrodynamic code DEBS ͓D. D. Schnack et al., J. Comput. Phys. 70, 330 ͑1987͔͒. This aspect ratio is equal to that of the Extrap T1 experiment ͓S. Mazur et al., Nucl. Fusion 34, 427 ͑1994͔͒. A numerical study of a RFP with this level of aspect ratio requires extensive computer achievements and has hitherto not been performed. The results are compared with previous studies ͓Y. L. Ho et al., Phys. Plasmas 2, 3407 ͑1995͔͒ of lower aspect ratio RFP configurations. In particular, an evaluation of the extrapolation to the aspect ratio of 8.8 made in this previous study shows that the extrapolation of the spectral spread, as well as most of the other findings, are confirmed. An important exception, however, is the magnetic diffusion coefficient, which is found to decrease with aspect ratio. Furthermore, an aspect ratio dependence of the magnetic energy and of the helicity of the RFP is found.

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RFP confinement physics studied on the Extrap-T1 device

Cited by 23 publications

References 27 publications

Numerical studies of confinement scaling in the conventional reversed field pinch

Numerical studies of confinement scaling in the conventional reversed field pinch

Confinement Scaling Laws for the Conventional Reversed-Field Pinch

Numerical studies of the reversed-field pinch at high aspect ratio

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