Improved Liquid Nitrogen Tank

In 2002, during routine usage, an internal weld failed within the Cameca liquid nitrogen tank which is used for the cold trap.  This resulted in the loss of the vacuum between the inner and outer walls of the tank, and this failure could not be repaired.  The original tank had a maximum time before refilling of only four hours.  Rather than replacing the tank with a new tank from Cameca, we elected to design a new tank in collaboration with a company from Berlin.  The new tank has a 3.5 liter capacity and has a load-free evaporation rate of less than 500 ml per day.  When used in conjunction with the standard cold  ring, the tank will hold LN2 for approximately 30 hours before refilling is required.