A tungsten guard limiter for EAST 4.6 GHz lower hybrid waveguide antennas

A new guard limiter (GL) with tungsten tiles is developed for the 4.6 GHz lower hybrid waveguide antennas (LHWA) on experimental advanced superconducting tokamak (EAST). The tungsten blocks assembly with copper chromium zirconium (CuCrZr) pipes employed for the LHWA lateral protections, which are accommodated to the LHWA profiles. The tungsten block with a wedge-shape in the toroidal cross section is designed to reduce the high temperature particle flux from LHWA side. The explosive welding technology is applied for fabricating the connecting water tanks between the main pipes and the cooling branches. The eddy current analysis under the vertical displacement event and the disruption of plasma indicates the maximum current is 1100A. The GL temperature field and structural stress are estimated using finite element method (FEM) based on ANSYS code. It is found that there is the peak temperature zone located on each center of the 12 sub waveguides zones. It indicates that the GL can be operated at peak power density with 12.92MW/m2 coming from the 4.6 GHz LHWA. It is also confirmed that the frame supports are safety for the GL structure based on the mechanics analysis.