Speaker
Ohjin Kwon
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P1.1052.pdf
Effect of the pressure gradient in the connection region on the
PBM stability
S.K. Kim1, S. Saarelma2, Y.S. Na1 and O.J. Kwon3*
1
Department of Nuclear Engineering, Seoul National University, Seoul, Korea
2
Culham Centre of Fusion Energy, Culham, U.K
3
Department of Physics, Daegu University, Daegu, Korea
*Email address: ojkwon@daegu.ac.kr
Abstract
The width of the plasma edge pedestal, formed by the transport barrier and the pressure at the
top of the pedestal strongly affect performance of tokamak fusion plasmas. To achieve the
plasma of performance target in future devices such as ITER, optimization of the edge pedestal
is required. However, achieving the improvement of the pedestal pressure and width still has
many difficulties and understanding of pedestal physics remains as a challenge. We have
investigated the dependence of pedestal properties such as the pedestal height and the pedestal
width on the pressure gradient just inside the pedestal top (𝜓𝜓N =0.9), 𝛼𝛼𝑖𝑖 , numerically using the
parameters of the JET-like plasma (𝐼𝐼𝑝𝑝 =1.4MA, 𝐵𝐵𝑡𝑡 =1.7T, 𝛿𝛿=0.37, 𝛽𝛽N =2.25) as the basis of the
analysis. We used MISHKA [1], an ideal MHD stability code and EPED1 [2], a predictive
model of the edge pedestal to analyse the edge stability and predict its structure. As a result,
improvement of pedestal properties can be achieved by reducing 𝛼𝛼𝑖𝑖 , which is consistent with
experimental findings [3, 4]. Larger Shafranov shift, 𝛥𝛥𝑠𝑠ℎ , also improves the pedestal width and
height [5, 6]. Positive correlation between poloidal beta and pedestal height [7, 8] is found to be
due to stabilization of peeling-ballooning mode (PBM) with 𝛥𝛥𝑠𝑠ℎ . From this result, we suggest
the possible correlation between pedestal structure and core pressure profile including the effect
of 𝛥𝛥sh and 𝛼𝛼𝑖𝑖 .
References:
[1] A. B. Mikihailovskii et al., 1997 Plasma. Phys. Reports 23(10) 844
[2] P. B. Snyder et al., 2009 Phys. Plasmas 16 056118
[3] N. Aiba et al., 2008 Journal of Physics: Conference Series 123 012008
[4] N. Hayashi et al., 2011 Nucl. Fusion 51 073015
[5] J. W. Connor et al., 2016 Plasma Phys. Controlled Fusion 58 085002
[6] P. B. Snyder et al., 2011 Nucl. Fusion 51 103016
[7] A. W. Leonard et al., 2008 Phys. Plasmas 15 056114
[8] I. T. Chapman et al., 2015 Nucl. Fusion 55 013004
