Tuesday, July 29, 2014

Moving Crushed Can Walls! Lab Book 2014_07_28

I made the last few fixes on the can crusher code port from IDL to +Sage Mathematical Software System and the can wall is now moving in simulation.  For a refresher on what the can crusher does and why the wall moves in the first place, see the embedded can crusher video post below.  Graphs were created showing how the current through the driving coil varies with time when the can is allowed to move and when it is not.  The leak detector is still broken, work will continue tomorrow on finding the root cause.

For background on the experiment in general, please scroll to the end.

Can Crusher Video

Can Crusher code
The can moving does influence the current through the coils.  Here’s a graph with the can moving, red and another without it moving, blue superimposed on the same plot.  The current graphed is the current through the driving can crusher coil, as opposed to the current through the can.

The x-axis denotes microseconds, and the y axis is in kA of current. 
The can movement code also looks good!  Here’s a graph of the can wall moving.  The horizontal line at the top is the can wall immediately before it begins to crush.  Each successive line as your eye moves down the y axis denotes the six segments of the can that are modeled, see picture at beginning of this entry.

The x axis is the segment index and the y axis is the radius of the segment.
Should this data be deposited somewhere even though it can be generated by the simulation? For the moment, I’ll just go with releases of the simulation on github:  https://github.com/hcarter333/cancrusher
Next:  Clean the code and make an initialization function.  Write up a simulation that captures the two curves shown above that uses the initialization function. 

Leak Detector Work

It is still unclear that the diffusion pump path is being vacuumed well.  The next step will be to attach the thermocouple gauge in place of the leak detector’s gauge on the nitrogen trap wall.

Hirsch's theory of hole superconductivity proposes a new BCS-compatible model of Cooper pair formation when superconducting materials phase transition from their normal to their superconducting state[1].  One of the experimentally verifiable predictions of his theory is that when a superconductor rapidly transitions, (quenches), back to its normal state, it will emit x-rays, (colloquially referred to here as H-rays because it's Hirsch's theory).

A superconductor can be rapidly transitioned back to its normal state by placing it in a strong magnetic field.  My experiment will look for H-rays emitted by both a Pb and a YBCO superconductor when it is quenched by a strong magnetic field.
This series of articles chronicles both the experimental lab work and the theory work that’s going into completing the experiment.

The lab book entries in this series detail the preparation and execution of this experiment… mostly.  I also have a few theory projects involving special relativity and quantum field theory.  Occasionally, they appear in these pages.

Call for Input
If you have any ideas, questions, or comments, they're very welcome!


1.  Hirsch, J. E., “Pair production and ionizing radiation from superconductors”, http://arxiv.org/abs/cond-mat/0508529 

No comments: