Abstract:Reconstruction of experimental axisymmetric equilibria is an important part of tokamak data analysis. Fourier expansion is applied to reconstruct the vessel current distribution in EFIT code. Benchmarking and testing calculations are performed to evaluate and validate this algorithm. Two cases for circular and non-circular plasma discharges are presented. Fourier expansion used to fit the eddy current is a robust method and the real time EFIT can be introduced to the plasma control system in the coming campaig… Show more
“…Constraints EAST, the magnetic reconstruction has been successfully used for the plasma control system (PCS) and some experiment analysis [10]. It was widely accepted [4,11] that with the magnetic diagnostics we can only achieve some integral parameters of internal plasma profiles such as the total plasma current I p , the internal inductance l i and the poloidal beta β p .…”
Plasma equilibrium is an important basis for tokamak plasma research. The equilibrium reconstructed from experimental diagnostics is a key element for experiments analysis and for theory study. The kinetic equilibrium has the profiles information (current or safety factor profile, kinetic pressure profile), which are key issues for some studies of physics. With the constraints of magnetic measurements, pressure profile and edge current profile, we achieved the first reconstructed kinetic equilibrium on EAST tokamak. The pressure and edge current profiles are based on the diagnostics and theoretical bootstrap current model. The kinetic equilibrium has the pedestal structure for H-mode plasma, which the magnetic reconstruction missed. This improved equilibrium is an important basis for some experimental analysis and theory studies on EAST.
“…Constraints EAST, the magnetic reconstruction has been successfully used for the plasma control system (PCS) and some experiment analysis [10]. It was widely accepted [4,11] that with the magnetic diagnostics we can only achieve some integral parameters of internal plasma profiles such as the total plasma current I p , the internal inductance l i and the poloidal beta β p .…”
Plasma equilibrium is an important basis for tokamak plasma research. The equilibrium reconstructed from experimental diagnostics is a key element for experiments analysis and for theory study. The kinetic equilibrium has the profiles information (current or safety factor profile, kinetic pressure profile), which are key issues for some studies of physics. With the constraints of magnetic measurements, pressure profile and edge current profile, we achieved the first reconstructed kinetic equilibrium on EAST tokamak. The pressure and edge current profiles are based on the diagnostics and theoretical bootstrap current model. The kinetic equilibrium has the pedestal structure for H-mode plasma, which the magnetic reconstruction missed. This improved equilibrium is an important basis for some experimental analysis and theory studies on EAST.
“…where B p is the poloidal magnetic field, V is the plasma volume, and B pa is the averaged B p along the last closed flux surface (LCFS), which is calculated by the EFIT code [14,15]. LHW power proportion is defined by P P ,…”
Section: Relations Of Lhw Power Proportion Versus L I and N E Versus L Imentioning
“…HIT [14], START [15,16], MAST [17], KSTAR [18,19], JT-60U [20], NSTX [21], TORE SUPRA [8,22], HT-7 [23], HL-2A [24], and EAST [25,26] devices. Equilibrium reconstruction is a critical part of the development of the fusion.…”
Gaussian Process Regression (GPR) is a Bayesian method for inferring profiles based on input data. The technique is increasing in popularity in the fusion community due to its many advantages over traditional fitting techniques including intrinsic uncertainty quantification and robustness to over-fitting. This work investigates the use of a new method, the change-point method, for handling the varying length scales found in different tokamak regimes. The use of the Student's t-distribution for the Bayesian likelihood probability is also investigated and shown to be advantageous in providing good fits in profiles with many outliers. To compare different methods, synthetic data generated from analytic profiles is used to create a database enabling a quantitative statistical comparison of which methods perform the best. Using a full Bayesian approach with the change-point method, Matérn kernel for the prior probability, and Student's t-distribution for the likelihood is shown to give the best results.
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