High temperature liquid metal heat pipes (LMHP) have exhibited startup difficulties when attempting to start from a frozen state. Inert gas loading is a recommended method to help frozen state startup. In the present work, a composite wick sodium heat pipe of the double walled artery type with a grooved artery channel and a long adiabatic section without screen wick was designed, fabricated and tested. The experimental heat pipe was tested inside a vacuum chamber for startup transients at several power inputs. The frozen state startup of the gas-loaded heat pipe with a long adiabatic section was successfully demonstrated. The transient hot zone temperature variation and hot front propagation were as predicted. Transient temperature profiles for frozen state startup and liquid state startup were compared

1. Sectional metal heat-pipe vacuum tube: Copper heat-pipe; Vacuum tube (magnetic-controlled Al-N-Al splash all glass evacuated heat-collecting tubes); Silicon gel sealing plug, aluminum heat-absorbing fins

2. Manifold box: Material of outer manifold: SUS304-2B stainless steel;
Copper header pipe; Material of insulation: Rock wool

3. Material of support: Stainless steel profiled bar with 1.2mm thickness

4. Packing: Export carton