Pressure profile shape constancy in L-mode stellarator plasmas A.V. Melnikov 1 , L.G. Eliseev 1 , I. Pastor 2 , J. Herranz 2 , C. Hidalgo 2 , A. Fujisawa 3 , T. Minami 3 , K.A. Razumova 1 , Yu.N. Dnestrovskij 1 , S.E. Lysenko 1 and J.H. Harris 4 1 Nuclear Fusion Institute, RRC "Kurchatov Institute", Moscow, Russia, 2 Laboratorio Nacional de Fusión, EURATOM-CIEMAT, Madrid, Spain 3 National Institute for Fusion Science, Toki, Japan 4 Fusion Energy Division, Oak Ridge National Laboratory, USA It is well known that the temperature profiles in a tokamak are self-consistent [1-3]. For the stellarators there is no temperature profile consistency [4]. The pressure profile consistency concept works in tokamaks [5]. There was found one example of the pressure profile stiffness in the pellet injection versus gas puff experiments in LHD [6]. The paper is dedicated to the investigation of this concept for the stellarators. Plasma temperature and density profile evolution during NBI heating of on- and off- axis ECRH heated plasma on TJ-II [7], for ECRH power scan on W7-AS [8] and CHS [9], high T i mode on CHS [10], on- and off- axis ECRH on W7-AS [4] and gas puffing on ATF [11] were observed (see Table 1). In the TJ-II stellarator, NBI heating (P NBI = 300 kW) of the target ECRH plasma (P ECRH = 300 kW) leads to dramatic changes of the plasma density and temperature. n e and T e profile evolution measured by high resolution Thomson Scattering diagnostics is shown in Fig.1 [7]. The values varied up to an order of magnitude, (0.3 <n e (0)< 6×10 19 m -3 , 0.2 < T e (0) <1 keV), the profiles varied from hollow to peaked (density), and from peaked to flat (electron temperature). In spite of the large difference in n e and T e profiles in the analyzed regime, their product, the plasma pressure P e , presents much stronger profile resilience in the confinement zone of the plasma column. It was found that the normalized pressure profiles P norm = P(!)/P(0) are much less scattered in comparison with plasma n e and T e profiles, see Fig. 2. In the CHS experiments with on-axis P EC = 150÷215 kW and density n e = (0.47÷0.95)×10 19 m -3 variation [9], the similar behavior was found: the increase of T e was accompanied by the decrease of n e , leaving P norm (!) practically unchanged. In the experiments with the standard major plasma axis (R ax =92.1cm, n e (0)= 4×10 19 m -3 , T e (0)~T i (0)=250 eV), and optimized one (R ax =87.7cm, n e (0)= 2×10 19 m -3 , T e (0)=200 eV, T i (0)=130 eV) [10], the same tendency was found, P norm remains almost constant. In high T i mode (n e (0)= 1.4×10 19 m -3 , T e (0)=700 eV, T i (0)=1 keV) [10], P norm almost coincides with the rest of discussed CHS profiles. In W7-AS experiment with on-axis P EC variation from 0.2 to 0.8 MW at almost the same density n e ~2×10 19 m -3 [8], the similar behavior was found: increase of T e was accompanied 34th EPS Conference on Plasma Phys. Warsaw, 2 - 6 July 2007 ECA Vol.31F, P-2.060 (2007)