Dynamical movements of electron density profiles in spherical tokamak merging processes

AbstractPlasma merging is a promising, innovative method of initial heating for spherical tokamak (ST) plasmas. Detailed measurements of the temporal evolution of electron density profiles during plasma merging processes in a TS‐3 device was studied using a CO2 laser interferometer with temporal and spatial resolution. The experimental observations show that the electrons are confined securely inside the magnetic separatrix in the moving plasma during the merging process. It has been found that the plasma particles are not ejected from the confinement region during the magnetic reconnection event, even though the magnetic structure of the plasma is changed drastically. Furthermore, it is shown that the electron density profile becomes hollow after plasma merging. These results indicate that plasma merging is effective not only as a method of initial heating of the ST, but also as a means of particle supply to the ST. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(2): 42–49, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10159