Design and Test of 4.6 GHz 500 kW Continuous Wave 3 dB High Power Divider

A 500-kW continuous-wave (CW) high-power 3-dB divider is designed for the 4.6-GHz lower hybrid current drive system in the Experimental and Advanced Superconducting Tokamak (EAST). A multistepped structure is used to increase the power capacity, and a water cooling structure is introduced to reduce the thermal deformation and gas breakdown, which keeps the maximum steady-state temperature of the divider below 60 °C under full-power (500 kW) operation. The result of the simulations of the electric field shows that the power capacity of the multi-stepped structure is more than twice compared with the traditional design. Moreover, the divider shows excellent performance in the low-power test, with low return loss (-35 dB) and similar division ratio (S ₂₁ = -3.004 dB and S ₃₁ = -3.035 dB) at 4.6 GHz. Both the division ratio test and the full reflection test were carried out successfully under 250-kW CW, which suggests that the development of the 3-dB divider satisfies the design requirements.