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Showing posts from July, 2014

Math Notes: Cylindrical r Coordinate Value to Trace a Spherical r Dependent on z

OK, so that was quite the title.  I haven't done one of these in a while, but classes are about to start again and i figured I may as well get started deriving things again.  Plus, I had to do it for the can crusher magnet simulation code[1] for the experiment[3].  Here's what's really going on.  I have a Sage function that will give me the magnetic field in the z direction produced by a coil of wire that sits at z = 0 and a has a radius of 'rcoil'.  I'd like to know the magnetic field produced by the loop of wire along a circular path that is perpendicular to the plane of the current carrying coil.  A circular path perpendicular to the plane of a coil kind of begs for spherical coordinates, but the routine I have takes a z coordinate and a radius coordinate in the cylindrical coordinate system.  In the picture above, the circular path is shown, and the coil of wire is at the diameter of the circle and perpendicular to the page.  Note:  For those reading on G+…

Simulations! Everywhere Simulations! Lab Book 2014_07_31

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
Vacuum Leak Detector Work Still looking into …

Leak Detector Down but Not Out, Code Crusher Code Objectified! Lab Book 2014_07_29

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 pump side of the system has burned out.  Since it shows no…

SageMath, Where Objects Rock and Scripts Don't

I moved the Sage simulation of the can crusher to an object oriented implementation today.  A few days ago,I was worried this might have been a bit of overkill and just a subconcious desire on my part to place the project in a code format I'm used to seeing things in.  I hit an example yesterday that convinced me otherwiser, and only a few short, OK,  and somewhat grueling, hours later, I had a much easier to use OO simulator.

Prior to yesterday, my usage mode of the can crusher code was as follows:
1.  Evaluate the cell that contained the initializaiton code.  There were some declarations of global varaibles and a little bit of code that atually ran on evaluation to place values in these variables.
2.  Evaluate the cells that contained the current calculating function and the can moving function separately.
3.  Evaluate the cell that contained the simulation code.

This, as far as I knew had to be done every time I wanted to change any values and run a simulation.  I was constant…

Moving Crushed Can Walls! Lab Book 2014_07_28

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 microseconds, and the y axis is in kA of current.  The can moveme…

Converting Metric Units, A Ham Radio Exam Study Page

Several of the exam questions involve converting metric units from one form to another.  By memorizing what a few unit prefixes mean, these questions become easy.  Look at the table below:
Prefix Size Multiply/Divide by pico one millionth of a millionth .0000000000001 or 1E-12 micro one millionth .000001 milli one thousandth .001 kilo one thousand 1000 mega one million 1,000,000 giga

Leak Detector Testing... Again Lab Book 2014_07_27

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 diffusion pump, but now attached to a thermocouple…

Standing Wave Ratio, or SWR, A Ham Radio Exam Study Page

When a transmitter sends radio  frequency energy down a transmission line to an antenna, some of that energy can be reflected back up the transmission line from the antenna towards the transmitter.


The amount of energy reflected is determined by how well the impedances of the antenna,  the transmission line, and the transmitter match.  The reflected rf energy can enter the transmitter and damage the final radio frequency amplifier stage.
The standing wave ratio, (SWR), is a measure of how much of the RF is reflected by the antenna.  An SWR or 1:1 indicates that none of the RF is reflected.  With an SWR of 1:1, the transmission line, (feedline), and antenna are perfectly matched.  Ratios higher than 1:1 such as 1.5:1 or 2:1 indicate that there is an impedance mismatch and that RF is being reflected back up to the transmitter.  Remember, SWR depends on how well the impedances of the antenna, (also called the load), and the transmission line are matched.
In modern transmitters, there is o…

*Physics, Phyne Art and Physicians*

*Physics, Phyne Art and Physicians*

The +Google Art Project is featuring one my favorite artists today, Thomas Eakins[1].  He's not my favorite because of his rather colorful life, (see [1] it' entertaining), or even because of his art as such. Although, I have to admit, I'm quite fond of his sailboat pictures, see below, and [2]!  Nope, as it turns out, Eakins has a connection to both fringe and mainstream science through the person of one Agnew Hunter Bahnson Jr.


Agnew Hunter Bahnson was a wealthy North Carolina industrialist who funded both fringe physicists like Thomas Townsend Brown and mainstream quantum gravity researchers.  He was the driving force behind the formation of the Institute for Field Physics at the University of North Carolina Chapel Hill.  The institute was direted by Bryce and Cecile DeWitt and Peter HIggs of Higgs boson fame did some of his work there.

But, what does any of this have to do with Thomas Eakins and his art?  The story is kind of long, …

PMT Rebuild and Can Crusher Code Progress: Lab Book 2014_07_24

The workbench before starting this morning.
Lab Book 2014_07_24     Hamilton Carter
Summary: Most of the day was spent building a new base for the PMT on the NaI detector.  I found almost all the necessary capacitors and was able to get the only size I couldn’t find by combining two other capacitors in parallel.  Only the connections to the coaxial connectors remain to be done.  The can crusher code port is progressing.  The initial implement of the function that models the movement of the can is complete.  There’s a bug in it that needs to be fixed.
Rebuilding the PMT Found all the capacitors that will be required to build up the new base. Should you want to rebuild the socket again, look for a box like this.
This is the portion of the circuit that has capacitors.  The capacitors that are going to be used have been laid out on the schematic as a visual check.



Here’s the schematic for the suggested PMT base circuit from the RCA tube manual[1].

These are all ceramic disc capacitors.  Th…

Magnetic Pulse Simultation Lives, NaI Detector Still on Life Support: Lab Book 2014_07_24

Lab Book 2014_07_23     Hamilton Carter
Summary: The NaI detector still isn't giving good results despite additional efforts to understand its operation and any possible problems.  Tomorrow, the base that provides voltage to the tube will be rebuilt.  The can crusher simulation code has produced its first correct looking current output results.  A pulsed mgnetic field from a can crusher will be used to quiench the superconducting Pb sample in the experiment  The cna crusheer simulation code is being used to model the magnetic fields that will be avilable.
If you're new to the experiment, scroll to the bottom for background.
The can crusher simulation code is alive!  I’m porting the original IDL code used in the AJP article[1] about the can crusher over to Sage.  The project is open source and is hosted on github[2].  The pulsed magnetic field from a can crusher apparatus like the one described in the article is going to provide the pulsed magnetic field required to quench the …