User:Johnny Joe Gonzalez/Notebook/Physics 307L/2009/09/16

Electron Diffraction

Electron Diffraction

Check for exposed wires or loose connections as voltages as high as 5kV can be used.
Use caution when running higher currents through the electron gun as that can damage the graphite sheet.
The electron gun has several components made of glass, care should be taken not to break any of the glass components.

The following materials will be needed for the lab:

First connect the electron gun to the power supply, and multimeter. (Most of this was already connected so I simply doulbe checked the connections.
I plugged everything in and turned the system on. I checked to make sure that the leds came on and I immediately checked the current, the current was read at 1.1mA.
I checked to make sure the calipers were working (note that there is both a mm and inch setting. I made sure the calipers were set to mm.
I then raised the voltage to about 500V, and then centered the green dot on the eletron gun.
The ring was difficult to observe at this point so after speaking with Dr. Koch, he suggested that we switch the polarity on our bias.
After switching the positive and negative connections on the bias the rings on teh electron gun became clearer to see (not much, but it did make a difference). However, the current on the multimeter spiked up after turning down the voltage, this could be due to the way things were connected, to stay on the safe side I turned everything down while recording my data.

1st measurement: voltage set at (4500), bias (16), Ring diameter: 41.9 inner ring: 29.9 multimeter current: .23mA
2nd measurement: voltage set at(4400), bias(16), ring diameter(40.9), inner ring(26.0), multimeter current: .21mA
3rd measurement: voltage set at(4300), bias(16), ring diameter(50.3), inner ring(30.9), multimeter current: .18mA
4th measurement: voltage set at(4200), bias(16), ring diameter(49.21), inner ring(28.2), multimeter current: .18mA
5th measurement: voltage set at(4100), bias(16), ring diameter(52.3), inner ring(31.2), multimeter current: .18
6th measurement: voltage set at(4000), bias(16), ring diameter(52.4), inner ring(32.8), multimeter current: (23.0)
7th measurement: voltage set at(3900), bias(16), outer ring(55.34), inner ring(32.3), multimeter current: .19mA
8th measurement: voltage set at(3800), bias(16), outer ring(54.6), inner ring(33.6), multimeter current:(.19mA)
9th measurement: voltage set at(3700), bias(16), outer ring(55.7), inner ring(33.8), multimeter current:(.18mA)
10th measurement: voltage set at(3600), bias(16), outer ring(56.2), inner ring(na), multimeter current:(.14mA)
11th measurement: voltage set at(4300), bias(16), outer ring(50.8), inner ring(29.2), multimeter current:(14mA)
12th measurement: voltage set at(4500), bias(16), outer ring(51.3), inner ring(28.5), multimeter current:(14mA)
- Side note:(When the voltage was set to 0, the current spiked to .30mA)

I marked the current over concerns for the equipment.