的低温恒温器（1），具有一个真空容器（2）和一个被冷却物（4），特别是（5）或低温容器（20），其中所述对象到在真空容器内被冷却（4）布置（2）的超导磁体线圈系统 中，所述（2）具有一个管颈（8），其导致被冷却物（4）的真空容器，其中，冷头的冷却臂（10）（11）设置在所述颈管布置为至少部分（8），到冷却臂 （10）围绕的封闭的空腔（9）形成，这是相反的要被冷却的物体（4）流体密封，所述腔（9）的正常操作至少部分地填充有第一低温流体（34）期间被填充，并且其中一个 （15）提供第一热耦合装置，适于在所述腔中的第一低温流体（34）的热耦合（9）与该对象被冷却（4），其特征在于，所述低温恒温器（1）还包括一个Pumpvo 装置（14），空腔（9）连接到该空腔（9），并且在冷端盖（11）的冷却功能失效的情况下空腔（9）被抽空。 本发明提供了一种低温恒温器装置，其中在主动冷却失效的情况下可以通过冷却臂以简单的方式进一步降低热负荷。

A cryostat (1), with a vacuum container (2) and an object to be cooled (4), in particular a superconducting magnet coil system (5) or a cryogenic container (20),
wherein the object to be cooled (4) inside the vacuum vessel (2) is arranged,
wherein the vacuum container (2) having a neck tube (8) which leads to the object to be cooled (4),
wherein a cooling arm (10) is arranged a cold head (11) at least partially in the neck tube (8),
wherein around the cooling arm (10) around an enclosed cavity (9) is formed which is sealed fluid-tight against the object to be cooled (4),
wherein said cavity (9) is filled during normal operation at least partially filled with a first cryogenic fluid (34),
and wherein a first thermal coupling means (15) is provided, suitable for the thermal coupling of the first cryogenic fluid (34) in the cavity (9) with the object to be cooled (4),
is characterized in that the cryostat (1) further comprises a pump device (14) to which the cavity (9) is connected, and with which the cavity (9) can be evacuated in case of failure of the cooling function of the cold head (11). The invention provides a cryostat, in which in a simple way, the heat load can be further reduced by a cooling arm, if the active cooling.