Post date: Jun 24, 2014 10:20:33 AM
We did the energy loss on the foil measurement using the same method as last time.
First we took a short (0.2us pulse) measurement without RF to determine the orbital frequency. Using the scope we could see it was 1.577MHz (saved file as 20140624_0000) so we set this as the RF frequency.
At first we started taking data with 6.6us injected pulse (same as last time) but we noticed that it was difficult to find the peak in the bunch monitor signal. We checked the DC coupling output and it looked like it might be beyond the point of saturation, so we tried reducing the length of the injected pulse to see if that helped. It did a little...
We also noted that the bunch monitor pulse shape changes as you change the RF voltage, and also changes with time as it captures/bunches/(debunches?) as Chris R had observed before. This made it difficult to do a quick back-of-the-envelope calculation as we went along.
We then went ahead and took the data as intended and included both the AC and DC (50ohm) coupled scope traces for the bunch monitor, and the RF coupler output as well. The attached file is the translation between the data filenames and the different applied voltage settings (applied this time using main control system rather than the signal generator used last time, in case that was introducing an extra error). As planned we took very fine data points at high voltage, and went right down to the low voltage range with slightly coarser data points.