Charlotte,
     Please see my point of view as below and for your reference.
 
 
Muffle                                                 隔离罩             75.0780

An enclosure with a rectangular or oval cross-section that is located between the heating elements and the parts being processed that contains the atmosphere required for the reflow soldering process.

Andy: 在加热单元和被处理件之间, 带有用于再流焊工艺氛围气的矩形或椭圆形截面的外壳.

个人认为 Atmosphere应该翻译成'氛围气', 不应该单单翻译为气氛...

Chalotte: 一个矩形或椭圆形的含有再流焊工艺所要求的气氛罩子，位于加热单元与被处理的部件之间。