【摘要】 <正> 根据IPTS(68),金点以上的温度由PLanck公式定义。目前,世界各国均采用光学高温计直接观测周围为纯金的石墨空腔腔底的辐射,对高温计定点。由于空腔的长—径比很大、且由高热导率的石墨制成以及空腔壁很薄等原因,通常忽略底面上的有效(视在)发射率的偏差和内外壁间存在的温度差。因此,空腔底即被看做为金点温度的发射体,并且其发射率也为金点温度对应的发射率。但是,实际上,当处于金点的稳定的热平衡时,总有一个固定的热流通过空腔口向外辐射,这部分热流损耗将由通过壁面传进的热量来补充,因此引起空腔内壁温度总是低于金点。而且,因为沿壁面的不均匀的温度分布,视在表面发射率略低于漫射、等更多还原

【Abstract】 According to the IPTS(68),Planck’s formula is used to define the tempe-rature above the gold freezing point 1064.43℃.At present,the instrumentadopted by most countries to realize the scale is the photoelectric pyrometerwhich is directly used for observing the spectral radiance of the bottom of agraphite cavity enclosed by pure gold.Because the depth-radius ratio of thecavity is large,and the cavity wall is very thin,the error incurred by thedeviation from one of the apparent emissivity of the bottom and the temperaturedifference between the internal and external wall is neligible.But,in practice,when the stable thermal balance is established at the goldfreezing point,there is always a constant thermal flux radiating outward throughthe cavity opening and causes the inner wall temperature to be always lower thanthe gold freezing point.In the present investigation,the integral,equation for the temperaturedistribution inside the cavity,and the relation between the emissivity and localtemperature have been derived,according to the basic idea of Geist.Theseequations have been solved using a digital computer for some cylindrical cavitiesand the results have been given here.更多还原