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T-10 – TEXTOR collaboration

T-10 – TEXTOR collaboration.

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T-10 – TEXTOR collaboration

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  1. T-10 – TEXTOR collaboration The self-organization of the tokamak plasma is a fundamental turbulent plasmas phenomenon, which leads to the formation of a self-consistent pressure profile. This phenomenon is investigated in the T-10 and TEXTOR tokamaks by means of different experiments. A number of results received at tokamaks in previous experiments relate to the OH and ECRH regimes, in which it was shown, that normalized pressure profile pN(r) is well conserved for regimes without ITB. Three more questions must be solved: 1. Do another heating methods gave similar results? 2. Will be the profile pN(r) universal for different dimension and geometry tokamaks if we will normalize the minor radius to the value rc= (IpR/kB)1/2, where Ip is plasma current, R is major radius, and B is toroidal magnetic field? 3. In order to understand the physical mechanism of pN(r) conservation we put the question: how quickly does it realize? Does it take place on a current reconstruction, heat diffusivity, or inertial time scale?

  2. Comparison of TEXTOR regimes under NBIH and NBIH + ICRH with the typical pN(r) for T-10 are shown in figure TEXTOR shots: #106221 I=24 kA; B=2.5T; PNBI=1.02MW; PICRH=1.425MW; # 106227 I=240kA; B=2.5T; PNBI=1.05MW; PICRH=0; and for T -10 ohmic shot So we conclude that pN(r) is independent on the heating method

  3. 2) pN(r) profiles for different tokamaks. = r/(IR/kB)1/2 R, m a, m k R/a RTP 0.72 0.164 1 4.4 JET 3 0.87 1.6 -1.8 3.75 T-10 1.5 0.3 1 5 TEXTOR 1.75 0.46 1 3.8 pN(r) is the same for quite different devices, if only we compare regimes with not pronounced ITB . The errors in this figure arise not only from usual error bars of ne(r) and Te,i(r) measurements, but also due to method of p normalization. In this figure the p(r) normalization was performed in plasma centre. This is possible in the cases of not very pronounced saw-teeth relaxations only. Existence of weak ITB near the main rational surfaces and some other effects, like MHD islands, also lead to the spreading of results. Nevertheless, we have reasonable coincidence between small circular tokamak RTP and large elongated JET results.

  4. 3) Old RTP experiments show that pN(r) shape conservation is established during a time tc<0.1  (Energy confinement time =3 ms in given experiment). Special experiments at T-10 with rapid current ramp up show that pN(r) restoration take place in time much faster than any additional current density can penetrate into plasma core and synchronously with the total current increase.

  5. The results of this works are published in: 1. The main features of self-consistent pressure profile formation K A Razumova, V F Andreev, A Yu Dnestrovskij, A Ya Kislov, N A Kirneva, S E Lysenko, Yu D Pavlov, V I Poznyak, T V Shafranov, E V Trukhina, V A Zhuravlev , A J H Donne, G M D Hogeweij, the T-10 team and the RTP team . Plasma Phys. Control. Fusion 50 (2008) 105004 (13pp) 2. Tokamak Plasma Self-Organization and possibility to Have Peaked Density Profiles in ITER K.A. Razumova , V.F. Andreev, A.Ya. Kislov, N.A. Kirneva, S.E. Lysenko, Yu.D. Pavlov, T V Shafranov, and T-10 team, A.J.H. Donné, G.M.D. Hogeweij, G.W. Spakman, R. Jaspers and TEXTOR team 22th IAEA conference (2008), Geneva, EX/P5-18 TEXTOR will continue physical experiments till the March 2009. So in the next year we can have common experiments and their analysis.

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