ABSTRACT Simulations have been performed to investigate the impact of radial variation of neutral atoms (neutral puff) on the edge plasma of small size divertor tokamak. It was demonstrated that, the variation of neutral atoms (neutral puff) in edge plasma of small size divertor tokamak generates additional large radial electric field and large radial electric field shear near separatrix which can significantly influence global confinement by affecting the transition from low (L) to high (H) confinement. This simulation was performed by using B2SOLPS0.5.2D fluid transport code based on a reduced form of the transport form of transport equations. These transport equations are implemented in B2SOLPS0.5.2D fluid transport code and solved for the parameters of Small Size Divertor tokamak. The results of simulation by fluid transport B2SOLPS0.5.2D code can be summarized as follow: 1) The Plasma Parameters are significantly effect by neutral atoms puffing in the edge plasma of small size divertor tokamak; 2) Contrary to previous expectation  of the predominant role of neutral viscosity on toroidal flux, anomalous transport was found to be mainly effect on toroidal flux; 3) Puffing of gas (neutral) in the edge plasma of small size divertor tokamak produce strong ITB; 4) Puffing of gas (neutral) in the edge plasma of small size divertor increase plasma density especially in SOL through charge exchange and ionization processes; 5) Puffing of gas (neutral) in the edge plasma of small size divertor has significant effect on the distribution of plasma heat flux; 6) The radial electric field is affected by gas (neutral) puffing in the edge plasma of small size divertor; 7) Puffing of neutral (atoms) in the edge plasma of small size divertor tokamak produce large radial electric field shear which contribute to L-H transition; 8) The centrifugal effect has no influence on distribution of the radial profile of parallel (toroidal) velocity of edge plasma of small size divertor tokamak during gas (neutral) puffing; 9) The bootstrap current in edge plasma of small size divertor tokamak is significantly affected by gas (neutral) puffing.
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