Lab Book 2014_05_19 Second Fiberglass Dewar Looks Good!

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 roughing pump, the vacuum held at .05.

The helium leak detector was used to find no leak in the hose or the fitting on the new Dewar. The Dewar valve was opened and the vacuum gauge moved to > 2. The roughing pump was left on the volume for several minutes and the vacuum reduced back down to 1.48.

Once the roughing pump was disconnected, the vacuum improved very quickly. At 17:20, the vacuum read 0.9 on the bottom scale, (all previous readings were on the top logarithmic scale).

17:20
17:20
21:05
21:05

The liquid nitrogen trap was filled at 21:05, and required two and a half Styrofoam cups of liquid nitrogen. It will be filled again in the early morning. The trap requires about six cups to fill from room temperature.

Comments

More Cowbell! Record Production using Google Forms and Charts

First, the what : This article shows how to embed a new Google Form into any web page. To demonstrate ths, a chart and form that allow blog readers to control the recording levels of each instrument in Blue Oyster Cult's "(Don't Fear) The Reaper" is used. HTML code from the Google version of the form included on this page is shown and the parts that need to be modified are highlighted. Next, the why : Google recently released an e-mail form feature that allows users of Google Documents to create an e-mail a form that automatically places each user's input into an associated spreadsheet. As it turns out, with a little bit of work, the forms that are created by Google Docs can be embedded into any web page. Now, The Goods: Click on the instrument you want turned up, click the submit button and then refresh the page. Through the magic of Google Forms as soon as you click on submit and refresh this web page, the data chart will update immediately. Turn up the:

Cool Math Tricks: Deriving the Divergence, (Del or Nabla) into New (Cylindrical) Coordinate Systems

Now available as a Kindle ebook for 99 cents ! Get a spiffy ebook, and fund more physics The following is a pretty lengthy procedure, but converting the divergence, (nabla, del) operator between coordinate systems comes up pretty often. While there are tables for converting between common coordinate systems , there seem to be fewer explanations of the procedure for deriving the conversion, so here goes! What do we actually want? To convert the Cartesian nabla to the nabla for another coordinate system, say… cylindrical coordinates. What we’ll need: 1. The Cartesian Nabla: 2. A set of equations relating the Cartesian coordinates to cylindrical coordinates: 3. A set of equations relating the Cartesian basis vectors to the basis vectors of the new coordinate system: How to do it: Use the chain rule for differentiation to convert the derivatives with respect to the Cartesian variables to derivatives with respect to the cylindrical variables. The chain

The Valentine's Day Magnetic Monopole

There's an assymetry to the form of the two Maxwell's equations shown in picture 1. While the divergence of the electric field is proportional to the electric charge density at a given point, the divergence of the magnetic field is equal to zero. This is typically explained in the following way. While we know that electrons, the fundamental electric charge carriers exist, evidence seems to indicate that magnetic monopoles, the particles that would carry magnetic 'charge', either don't exist, or, the energies required to create them are so high that they are exceedingly rare. That doesn't stop us from looking for them though! Keeping with the theme of Fairbank[1] and his academic progeny over the semester break, today's post is about the discovery of a magnetic monopole candidate event by one of the Fairbank's graduate students, Blas Cabrera[2]. Cabrera was utilizing a loop type of magnetic monopole detector. Its operation is in concept very sim

Copasetic Flow

Search This Blog