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| Title | PV | Description |
|---|---|---|
| System Status | :STATUS | This indicates the aggregate health of the digital processing chain for this axis. Clicking on this will bring up the System Status page where the source of any alarm indication here can be located. |
:SEQ:MODE | This field shows a brief summary of the sequencer setup, in the example above it says "Sweep: all bunches (-42dB)", which means a multi-bunch sweep over all bunches with an excitation strength of -42dB over all bunches. | |
| Feedback Settings | :FIR:GAIN_S | This controls the overall level of FIR gain. |
:FIR:0:PHASE_S | This controls the phase of the FIR filter for FIR #0 | |
:BUN:MODE | This shows a brief summary of the feedback status when the sequencer is not running, in the illustrated example feedback is not active. | |
| Bunch motion standard deviation | :ADC:MMS:STD | This shows the standard deviation of bunch motion for this axis, see Min/Max/Sum for more detail. |
| System | This button brings up the MBF System View providing links to all other control pages. | |
| Tune, Phase | $(prefix):TUNE, $(prefix):PHASE | These two PVs are provided by the tune fitter from the data captured by detector #0. Clicking on this will bring up the Tune Fitting Overview page. |
| Tune Only, Tune Special, Feedback On & Tune | These three buttons will automatically configure the selected axis for feedback and tune sweep as appropriate and as configured. |
The following content is
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specific to Diamond.
The TMBF loop was closed as instabilities toward the end of the train started to grow significantly with the even fill generated by the FPG. It is now running in the mode ‘Feedback On & Tune’, where oscillations on all but one bunches are damped, and one bunch is used to measure the tuneis now (2018+) always required to be in ‘Feedback On & Tune’ during operation at full current.
Turning on the TMBF
Normally, there is no need to switch the TMBF off at any time. It will work happily behave with no beam, injection, stored beam.
However if it is needed:
- Start in 'Tune Only' mode.
- Inject some current (10mA), set the tunes correctly.
- Select ‘Feedback On+Tune’ (This will start with a very low gain just in case the phase is incorrect).Slowly increase the gain from -24dB in steps of 3dB to a final level of 0dB. Watch for instabilities on bunch display and pinhole camera and adjust phase in small steps if they appear.
- Change the Displayed 'Tune Phase' using the 'Feedback Settings Phase' to be +- 180 degree.
- Increase the gain to what you need (0-12dB, consult current requirements).
Modes of operation
- Tune Only - This is a narrow band high resolution measurement mode for use in user time (if feedback is not desired which is not usually the case). This excites all bunches.
- Tune Special - This is a wide band coarse resolution measurement mode with more power for use during beam studies or troubleshooting. This is visible to beamlines!
- Feedback on and Tune - This is the usual operating mode during user time. This is a narrow band high resolution tune measurement using a single bunch combined with feedback on all other bunches.
Troubleshooting
Should any problems appear (like blowup of the beam while NOT injecting), the following escalation procedure should be applied:
- Switch TMBF into ‘Tune Only’ mode by selecting this function from the TMBF-01 and TMBF-02 panels available on ‘Diagnostics Storage Ring Overview’
- Switch TMBF into ‘Tune Special’ mode by selecting this function from the TMBF-01 and TMBF-02 panels available on ‘Diagnostics Storage Ring Overview’
- should Should this not help, switch of the amplifiers, by selecting ‘Off’ from the AMP-01 and AMP-02 panels, also on ‘Diagnostics Storage Ring Overview’
- Should this not help, then the problem is caused by something other than the TMBF system So you might just as well switch the TMBF back on, by reversing the above.
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Changing RF can cause problems in two different ways:
- The drift of the RF frequency due to the action of the RF feedback can cause the tune magnitude to reduce or the tune to move out of the frequency window swept by the TMBF. This can be fixed by carefully adjusting the TMBF phase.RF jumps phase changes caused by switching to single cavity operation, switching cavities, adjusting the balance between the cavities, or turning the RF on and off can cause the FPGA on the TMBF to lock up. A power cycle of the TMBF electronics is then requiredlead to undesired side effect in the MBF.