LINK TO MEASURING VI
LINK TO RESPONDING VI
LINK TO RUNNING
In order to measure the amount of liquid helium in the system at any given moment, a user interface with the platform LabVIEW is needed. The level of liquid helium is controlled by the position of the run valve, which allows it to flow from the separator to the nose (for more information on this process, follow THIS LINK and find Low Temperature: Cryogenics). The run valve has can have any position between 0 and 3 "turns", with 0 turns being completely closed and 3 turns being completely opened. LabVIEW is used to provide a means of automatically measuring and responding to the helium level inside the tank. This is done by running two separate Virtual Interfaces in unison, a Measuring VI and a Response VI.
The Response VI controls the run valve position. It reads the current level from the Measuring VI, and reacts in order to ensure that the level stays near a user-specified target level. This is the larger of the two VIs and it interacts with the instrumentation involved, like the run valve itself.
When the VI is first opens up, the first panel to appear is the interface. This panel is where you can comprehensively see how full the tank is at any given moment, and can change a few control factors of the code.
One of the controls that will need to be set before the VI can run is the file path (see below). You should set this to a location on your computer's hard drive.
Next, you will need to set the standard deviation of the flow rate randomness curve. In order to provide a more realistic measurement of the level, randomness was introduced into the flow rate equation to account for small variations in flow. Also included in the interface are indicators for certain values pertaining to the system at that iteration. For instance, above the standard deviation control there is a "theoretical flow rate" indicator, (in other words, the flow rate calculated before randomness was applied) and below it there is a "realistic flow rate" indicator (the flow rate with randomness taken into account). The blue tank is comprehensive indicator for the level at each iteration. It is measured in percentages of 0 - 100 % full.
To the right of this section of the interface there are indicators for the current valve position, the current iteration number and the new level as calculated by the VI. These values are calculated every 1 second.