| dc.description.abstract | The line N is a special superconducting line in the LHC, which is external to the
cold mass. The line is connected to the cold mass every half cell, and due to this
it will have the same operating pressure and temperature as the magnets. In the
dispersion suppressor zones the cool down of the line N is slightly delayed with
respect to the magnets, due to its geometrical design.
As this delay may affect the readiness of the accelerator for operating, it is
desired that it is reduced to less than two hours. In a test called String 2 a full
scale model of the LHC cell was built to validate the LHC systems in working
condition, and to investigate the collective behavior under various conditions.
During this test, there was installed a copper plug in line N. The result showed
that the cool down time of the line was delayed by more than two hours.
After this test there has been designed a new copper heat exchanger that is used
in the line N to make additional lambda fronts, and by this lower the cool down
time of the line. The design of this heat exchanger has been chosen by
mathematical models that were compared to the String 2. The finished heat
exchanger has never been tested, but it is presumably that it will reduce the cool
down time in line N to less than two hours.
The goal of this project is to follow up a test of the heat exchanger at the
cryogenic laboratory at CERN. I will also try to make a computer model of the
heat exchanger, which can be verified by the result of the test. The results from
this computer model can later be used to calculate the cool down time of line N,
and then see if the target for the cool down time is reached. | en |
