Tungsten limiter tests in ASDEX Upgrade

In order to prepare for tungsten coating to be applied to the low field side poloidal guard limiters, 1 μm W-coated CFC limiter tests have been performed in ASDEX Upgrade. The test limiters were exposed to H-mode deuterium plasmas with the neutral beam heating at maximum 5 MW for approximately 1 s. The power flux deposited on the test limiter was calculated by solving the 3-D heat conduction equation by using the measured time dependent surface temperatures as boundary conditions. The experimental results show that the heating with more radial NI beams leads to a higher local deposited power with a longer radial decay length related to banana particle loss. Strong localized W erosion was found at the tip of the test limiter due to arcing, which obviously depends on the neutral beam injection (NBI) geometry.