Visualization of 3He Nucleate Boiling Below 1 K

Boiling behavior of liquid 3 He below 1 K was visualized as shadowgraph image. A light source and a video camera (or still camera) were arranged at room temperature. The light was guided to the 3 He cell by an optical fiber, and the shadowgraph image was transferred to the camera by an image fiber. The 3 He bubble formed on the heated copper surface was spheroid-like due to the low surface tension. The size at departure from the surface and the relative bubble formation rate were measured as a function of heat flux. The previously obtained heat transfer curve could be explained qualitatively by this boiling behavior.