helium layer

例句：

1. 1. The helium layer is a thin layer of gas that surrounds the Earth's atmosphere.
   氦层是围绕地球大气层的一层气体薄层。
2. 2. The helium layer plays a crucial role in the formation of the planet's magnetic field.
   氦层在形成行星磁场方面起着至关重要的作用。
3. 3. Helium layers are used in spacecraft to protect them from radiation and other harmful effects.
   氦层被用于航天器中，以保护它们免受辐射和其他有害影响。