2023-03-24

Machine Status

Vacuum is 2.5e-7 Pa (yesterday was 2.4e-7). 

TORA signal is greater than around ### mV at injection.

FAB signal is large and requires 1 V/div at injection.

Measurements

We will start with coasting beam lifetime.

Coasting beam lifetime will be acquired by recapturing and measuring intensity. The primary signal-of-interest is bunched beam before and after coasting. The FAB has strong harmonic-7 signal, so the TORA has been connected to Channel 2 of the scope. Because we have three active channels, the sample rate has reduced to 250 MSa/s. The FAB has an 80 MHz low-pass filter, so the sample rate is technically OK, although we expect increased noise. The TORA does not have a physical low-pass filter, so the scope channel was set to 200 MHz bandwidth and some aliasing is expected on C2. Since the amplifier bandwidth is 80 MHz the bunched-beam signal is still expected to be well resolved, the aliasing is primarily expected to add some noise; this is the best we can do as we don't have another suitable low-pass filter.

Measurement 1 - Coasting Lifetime with 10 ms Coast

No Schottky data acquired because the coast is so short.

Delay 1 is 25 ms
Delay 2 is 50 ms

Measurement 2 - Coasting Lifetime with 50 ms Coast

Delay 1 is 25 ms
Delay 2 is 72 ms
Delay 3 is 107 ms

Measurement 3 - Coasting Beam Lifetime with 100 ms Coast

Delay 1 is 25 ms
Delay 2 is 72 ms (47 + 25)
Delay 3 is 120 ms (47 + 100 - 25 - 2)
Delay 4 is 157 (47 + 100 + [25 -15])

Measurement 4 - Coasting Beam Lifetime with 200 ms Coast

Delay 1 is 25 ms
Delay 2 is 72 ms (47 + 25)
Delay 3 is 220 ms (47 + 200 - 25 - 2)
Delay 4 is 257 ms (47 + 200 + [25 - 15])

Measurement 5 - Coasting Beam Lifetime with 300 ms Coast

Delay 1 is 25 ms
Delay 2 is 72 ms (47 + 25)
Delay 3 is 320 ms (47 + 300 - 25 - 2)
Delay 4 is 357 ms (47 + 300 + [25 - 15])

Measurement 6 - Bunched Beam Lifetime

We have increased the scope window to 100 ms (and necessarily reduced sample rate to 125 MSa/s) to get the bunched beam signal in fewer acquisitions.

Delay 1 is 25 ms
Delay 2 is 72 ms (47 + 25)
Delay 3 is 320 ms (47 + 300 - 25 - 2)
Delay 4 is 357 ms (47 + 300 + [25 - 15])

Measurement 7 - Case 1 - 2.36 kV

Scope moved back to 500 MSa/s, FAB and RF only, 50 ms window.

Measurement 7 - Slow RF Switch-on for Beam 2 - One Beam Only - 6.96 ms Acceleration

It's only one-beam, so we can't make a comparison, but the initial result looks closer to the usual beam-1 than the usual beam-2. A two-beam case will be made to check. We will continue with the cases in the meantime. 

Measurement 8 - Case 2 - 2.36 kV

Measurement 9 - Case 4 - 2.36 kV

Given the very limited time remaining to acquire data, we have decided to forego taking case-3. 

Measurement 10 - Slow RF Switch-on for Beam 2 - Two Beams - 6.96 ms Acceleration

Using the Welch method to compare data from the 22nd and 24th shows that dP/P on the two days was very similar. The slow RF switch-on does not appear to have improved the condition of beam-1.