Mike's Notes from the Lab

LabView Control Software for Rigaku Geigerflex XRD

October 11, 2017 Michael Buettner Comments 0 Comment

The original control software for our Rigaku Geigerflex XRD machine is DOS-based, with a rather non-intuitive text-based user interface. To be able to run this software on a modern computer requires installing DOS and the control program on a virtual machine (we used VirtualBOX). To get the data files out of the virtual machine environment a shared folder is used that holds the files and allows access from both DOS and the Windows 7 host system. All of this is…

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Visualizing Magnetic Domains with the NanoMOKE 3

August 3, 2017 Michael Buettner Comments 0 Comment

The NanoMOKE 3 software LXPro 3 has a function built in to image domains and their switching magnetization called 3D looping. For some of our users this measurement mode was not sufficient to catch the domains mid-switch as it happens very fast. You can observe the switching in almost live video by following these steps: Set fields to “manual fields” Set a saturation field Start imaging, select “Kerr Rotation” as display Right-click in the image area and select “Set as…

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Sanpla Dry Keeper Desiccator Repair

May 11, 2017 Michael Buettner Comments 0 Comment

The Sanpla Dry Keeper Automatic Desiccator uses a granular desiccant to dehumidify the inside of the cabinet to about 30-40 % RH. The desiccant is held in a basket equipped with a heater for regeneration when saturation is reached. The instrument goes through a 30 min regeneration phase followed by about 4-5 hours of moisture removal. This cycle is controlled by a mechanical switch driven by an AC synchronous motor. The instrument in our lab didn’t work any more, meaning…

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Lowering the Temperature of Liquid Nitrogen

April 21, 2017 Michael Buettner Comments 0 Comment

Liquid nitrogen (LN) is widely used in experiments where cryogenic temperatures are needed. The temperature of LN at 1 atm is 77.3 K. Some experiments might require temperatures slightly below this limit. In the phase diagram we are on the equilibrium line between the liquid and the gaseous phase. To push this equilibrium to lower temperatures, toward the triple point we need to lower the pressure. The equilibrium temperature at the triple point is 63.1 K. One way of…

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Troubleshooting the XRF Detector

March 30, 2017 Michael Buettner Comments 0 Comment

Some time ago we received donated equipment through the Laboratory Equipment Donation Program (LEDP, www.osti.gov/ledp/). It was a Kevex Omicron XRF machine. It was in very good shape and after setting up an old Windows 98 computer to run the control software, I began testing the instrument. The x-ray source seemed to work fine, but I just couldn’t receive any signal from the detector except some spurious counts that didn’t make any sense. I therefore took a closer look at the…

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Upgrading the MicroMag 2900 AGM Linear z-Slide

March 7, 2017 Michael Buettner Comments 0 Comment

The design of the MicroMag 2900 AGM has a few shortcomings. One of them is the linear z-slide mechanism that the instrument came initially equipped with. It is a Velmex Manual UniSlide (Model # SPA2509DM-S2.5, see picture) with Rapid Advance, scale, and Vernier. The slide features a limited fine adjustment by means of a clamping-like drive that can be engaged/disengaged by operating a lever (B). When engaged the slide is clamped onto the center rod (C) which can be fine…

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A Simple Homopolar Motor

February 24, 2017 Michael Buettner Comments 0 Comment

For an annual outreach event at my institution I’m putting together a few easy experiments around electromagnetism. The program for high school students is aimed at getting them interested in STEM. Searching the internet I found a beautifully simple example of an homopolar motor. All that is needed is: A AA battery A few disk shaped Neodymium magnets, slighty larger diameter than the battery Bare copper wire (I used 14 AWG) The battery sits on the stacked magnets. The wire…

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A Probe Safety Clip for the MicroMag 2900 AGM

February 17, 2017 Michael Buettner Comments 0 Comment

This is a little project I finished some time ago to address one recurring problem with the PCM MicroMag AGM. The AGM probe is held to the transducer by a 7 pin connector (Amphenol/WPI 126 Series Miniature Hexagonal Connector), as shown in the picture. Initially, the pins sit snug in the receptacle and hold the heavy probe in place. However, frequent plugging and unplugging, as common during use, leads to the pins becoming less tightly fit. The probe is then…

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New Purpose for Casting Tape

February 13, 2017 Michael Buettner Comments 0 Comment

I’d like to talk about something I came across a few weeks ago. Due to an accident leading to a broken wrist the ingenuity of glass fiber casting tape came to my attention. Never having had the need for a cast, the technical development in this field passed by me. Googling yielded the product in question: 3M ScotchCast Plus Casting Tape. You briefly soak it in water; then it becomes sticky, while still soft and pliable. Within minutes it hardens…

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Repairing a Probe for the PMC MicroMag 2900 AGM

February 8, 2017 Michael Buettner Comments 0 Comment

Above is a picture of the AGM probe. The sample carrier (quartz slide) can be seen on the right end of the probe. The quartz slide is attached to a thin polyimide tube that is itself attached to a piezo-like sensor to detect the deflection. The quartz and the tube tend to break easily over time. Sending the probe in for repair is costly and therefore I sought ways to repair the probe myself. Broken parts (either quartz or tube)…

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