11/11/18
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Completed
- Ghost beam test 1a:
- Ran 100uA electron beam for 5, 10, 15, and 20 minutes. After each run, I turned off the electron beam and measured the intensity of the ghost beam 0, 2, 4, and 6 minutes after inserting viewer 2. These measurements should hopefully determine the lifetime of the ghost beam and whether or not it is stable.
- Ghost beam test 1b:
- Repeated test 1a, but with 250uA. Will compare these measurements with those from the 100uA runs.
- Lifetime measurement of a high-intensity ghost beam: I steered a 250uA electron beam for 10 seconds into the beam pipe. Although this caused a brief and sharp increase in vacuum levels, it also effected a ghost beam of high intensity of which I measured the intensity every minute for 10 minutes.
In Progress
- Analyzing the above tests.
- Using GPT to create a 1 million randomized electron distribution at GTS. After the null result of the 1 million randomized ion distribution and since the ghost beam seems to be made up of electrons, it is possible we are trapping electrons instead. This simulation should help to determine whether or not this is the case.
- Performing various diagnostics on the "ghost beam" to determine its origin. We can use steering magnets as a "mass spectrometer", i.e. we can measure the "ghost" particle's charge-to-mass ratio.
Future Work
- Performing beam diagnostics on Mamun's "ghost" beam:
- Using steering magnets as a "mass spectrometer." We should be able to determine the mass of the ghost beam particles using their charge-to-mass ratio.
- Using a BPM to measure characteristic frequencies of ions trapped within the electron beam. In theory, we should be able to determine what kinds of ions get trapped within the electron beam potential.
- Using a spectrometer to measure emission lines due to ionization of residual gas molecules -- Electrons from the electron beam excite electrons in residual gas molecules to a higher energy state. These excited electrons then drop back down to their original energy state and emit light. Each gas molecule has characteristic emission lines associated with it, thus, we can see which kinds of ions are present in the electron beam.
- Rapidly preparing an abstract, conference proceeding, and grant applications for IPAC 2019 in May.
- Writing and publishing a paper on simulations of ion bombardment of polarized photocathodes using Joe's measurements. Will either use GPT or IBSimu to create a simulation of ion production at GTS.