In the apparatus, an insert dewar joined directly to a coiled tube of liqeid nitrogen dewar. The dry nitrogen gas is pressed to the liquid nitrogen and the cooled nitrogen gas is jetted to the sample tube.

• 其原理是把插入式杜瓦直接插在液氮杜瓦的螺旋管上,将干燥氮气压入液氮中,然后把冷却后的氮气流喷在样品管上,使样品管的温度降低。