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In the path of the beam, after the axicon, we have placed a camera on a movable rail. This allows us to record the intensity of the Bessel beam at several different positions. As of August 2023 we have only acquired one data set of 20 images taken at each of 10 positions. Below is an example of the analysis process. The raw image is shown on the left. Then the image is scanned for a maximum and smaller ROI is set around the located maximum, shown in the second image. After this, a two dimensional zeroth order Bessel function of the first kind squared is fit over the data as shown in the third image. The amplitude of each fit Bessel is stored and plotted at after each image is analyzed.
Downstream Holed
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Mirror Cameras (Near and Far)
My mentor Robert and I built and installed a new apparatus in the sector 20 tunnel at the position of the IPOTR. On the right you can see we have two cameras that will help to characterize the effects of the plasmas index of refraction on the Bessel pulse. The Near field camera reimages the Bessel beam at about 2/3rds of the way through the plasma. When we have gas in the system, we will be able to see a broadening of the focus of the Bessel beam. The Far field camera views the Fourier transform of the beam as a ring shape. When there is gas in the system, the creation of the plasma should cause the back of the beam to be bent inwards so we will see a thickening of the ring. Unfortunately, data has not been taken using this apparatus yet.
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