Systematic measurements of the plasma potential and the electron temperature during the L-mode and ELMy H-mode on several large European facilities by using ball-pen probe technique. Project ID: KJB100430901 Provider: Grant Agency of the Academy of Sciences Period: Jan 01, 2009 - Dec 31, 2011 Principal Investigator: Mgr. Jiří Adámek, Ph.D. Co-investigators , , , , Aims of the project: The investigation of the electric field, its fluctuations and ExB drifts remains one of the most important tasks in the context of anomalous edge plasma and momentum transport. The ball-pen probe is used for direct measurements of the plasma potential because the electric field and its fluctuations derived from the plasma potential are independent on the electron temperature. Ball-pen probe measures the plasma potential with good time and space resolution and it was already tested on different European facilities (ASDEX Upgrade,RFX,CASTOR). The ball-pen probe combined with Langmuir probe provides also the electron temperature with same parameters. Particular attention will be devoted to the measurements during the ELMy H-mode. The investigation of ELM structures and understanding of their physics is crucial in order to control their impact on the life time of ITER tokamak. The project contains the numerical simulations in code SPICE2 to describe the plasma in the vicinity of the probe.