Measurement of divertor neutral pressure in EAST tokamak by ASDEX pressure gauge

In the tokamak plasma operation, divertor neutral particles play a key role in the study of fuel recycling, heat load mitigation, plasma confinement, and so on. Therefore, the in-situ measurement of neutral pressure in the divertor region is essential for the divertor physics studies. Two ASDEX pressure gauges were installed in the lower divertor dome region and passive plate region, respectively, for the in-situ pressure measurement. Experimental results show that, the ASDEX pressure gauge diagnostic is more sensitive, and its measurement on divertor neutral pressure is about 100 milliseconds faster than the external gauge of the divertor. Moreover, the ASDEX pressure gauge diagnostic is applicable for long pulse and high power plasma operation, and the in-situ pressure measurement of the divertor during over 200 s and higher than 10 MW discharges were successfully achieved in EAST. In addition, ASDEX pressure gauge diagnostic sensitively reacts to the changes in plasma parameters, and the neutral pressure is found to be significantly influenced by the plasma heating power. These results provide powerful technical support for the key divertor physical studies in EAST tokamak and the future fusion devices.