Copasetic Flow

Work is proceeding on testing the systems that will be used in the experiment.  While the glass Dewar’s silvering blocks gamma radiation in the 22 keV range substantially, it fits nicely inside the yoke magnet whose field can be easily measured.  A temperature gauge was located; vacuum testing was started for the inner Dewar and lid, (including the instrumentation ports.)  Scroll to the bottom for the background of the experiment. All about the temperature gauge Today, just pictures of the gauge.  For an idea of scale, its rectangular footprint is about the size of a nickel.  The four wire sockets on the left are for attaching a four point probe to measure the resistance of the gauge. The Dewar lid with all the attachments The easiest way to seal the Dewar lid was to put the instrumentation stick back in place.  An experimental stage to hold the Pb sample still needs to be designed. Testing the vacuum pump before testing the D...

Summary: Excuse a brief moment of frivolity please.   OMG, This is So *#($&#@ cool!!! OK, now that I've got that out of my system we can move on.  The can crusher simulator port from IDL to Sage is complete and it's working spectacularly well!  I was able to run simulations to find out what the temperature of the can would increase to due to the magnetic pulse.  I was also able to plot the magnetic field in a sphere around the pulisng coil to determine if the coil as specified would provide a high enough magnetic field to quench the entire superconducting Pb sample at once.  Meanwhile, work is continuing on fixing the vacuum leak detector.  I was unable to find an instrument panel bulb to attempt the kluge fix suggested below, so it looks like I'll be ordering a replacement part instead. If you're new to the experiment, you can find background by scrolling to the bottom of the page. Lab Book 2014_07_30     Hamilton Carter ...

Alternate Title:  How Could Something So Pretty be So Broken? Summary It finally became too cumbersome to work with the can crusher simulation code in script form.  the bulk of this morning was spent in meetings and reworking the can crusher code to be object oriented.  The object oriented refactoring was completed and tested and works great!  It’s now very easy to run multiple simulations and compare their results.  The next step is to write code that runs the simulation to the peak current point and then plots the magnet field in on a spherical surface that will correspond to the surface of the superconductor Pb sample being used.  There are other simulations that need to be done as well.  For example, finding out how the current traces change when the temperature of the material is 4.2 K, the temperature of liquid helium. The leak detector problem has been isolated.  The Pirani gauge that measures the vacuum on the diffusion pu...

Summary: 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 ...

Summary: The leak detector stopped working correctly several weeks ago.  It didn't exactly depart his mortal coil so much as just stop being useful.  Sort of like a major league baseball catcher hunkered in a hockey goal.  It looks sort of like it has the right equipment, but it obviously incapable of performing it's tasks in any sort of meaningful way.  It boils down to this, the mechanical roughing pump is still pulling a vacuum that should enable the diffusion pump, responsible for doing the detailed vacuum work, to switch on, and yet the diffusion pump abjectly refuses. If you're new to the experiment, the background of what's going on here in broad strokes can be found at the bottom of the post. Lab Book 2014_07_25     Hamilton Carter Leak Detector Work Leak detector testing was resumed.  The first test was to check the vacuum on the end of the vacuum hose coming from the roughing pump and normally attached to the diffusio...

Superconductor Quenching Magnet Cooling Supply Work The magnet that will be used to quench the superconductor in our experiment is water cooled.  So is its power supply.  The water chiller that will provide the cooling was checked out and filled.  The plumbing to the supply was constructed and tested.  Two of the water lines required SwageLocks rather than Parker fittings to prevent leaks. The superconducting sample is to be placed in a liquid helium Dewar during the experiment.  Work is being done to check the status of a second Dewar that can be used as a backup to the first.  At present, the leak detector for this work is not functioning properly.  Some time was spent on debug of the system with no conclusive answers found. New to the game?  Scroll to the end for background on what this is all about. Leak Detector Debug Looking into why the leak detector no longer pulls down to < 10^-2 Torr quickly, (at all?).  Cleaned th...

Lab Book 2014_05_20     Hamilton Carter Summary The fiberglass Dewar vacuum held.  The vacuum inlet was plugged to prevent any possible leaks there, and it was stored.  A 480 V three phase outlet for the magnet power supply was located. 4:30 AM Liquid Nitrogen Trap Refilling Refilled the liquid nitrogen trap that prevents oil vapor from the diffusion pump from migrating opposite the intended vacuum flow into the Dewar’s vacuum jacket.  The liquid nitrogen condenses the oil vapor in the bottom of the small container, (the trap), that it cools. The trap took two and a half cups of liquid nitrogen to refill.  The vacuum and leak detector readings before and after the fill are shown below. There was no noticeable improvement in the vacuum and leak readings before and after the Dewar refill.  This makes sense because the Dewar still had liquid nitrogen and was performing its intended function. Vacuum and leak readings...

Lab Book 2014_05_19     Hamilton Carter Summary Started work on leak checking a second fiberglass Dewar.  So far, the jacket seems to be holding vacuum well.  The auxiliary roughing pump was pumping more vapor into the system than expected.  Once it was taken out of the circuit, the diffusion pump quickly pulled the jacket back down to a reasonably good vacuum.  No leaks were detected in any of the vacuum junctions, or anywhere on the jacket. Testing a different fiberglass Dewar.  I wire brushed the old Teflon tape off the vacuum port and and attached the lead detector after putting on new Teflon tape. Just pumping the hose up to the Dewar, it looked like there might be a leak.  When the rouging pump was taken out of the system after a minute or two, the pressure went back up from about .05 to above .1 rather quickly.  However, after letting the roughing pump work for 28 minutes, when the valve was closed removing the ro...

Lab Book 2014_05_16     Hamilton Carter Summary There's a minor setback.  The fiberglass Dewar has a leak.  On the theory side of things, the relativistic range equation is shown to be proper x velocity times the rapidity of the y component of velocity divided by the acceleration due to gravity which is about what you'd expect it to look like if you first looked at the classical result and then squinted.  Work is being done to determine what, if anything, to make of the result.  Notes and a brief Mathematica file are included. Leak testing the fiberglass Dewar today.  I’m also looking through the second Tehran paper . There is a leak at the Teflon joint that is away from the Dewar.  It’s a rather small leak that can’t be detected using the roughing pump gauge. I've very slightly opened the Dewar valve and begun pumping on the large volume.  After about five minutes, the vacuum was back down to 3 * 10^-1. ...