Libera Brilliance+
Libera Hadron
Libera LLRF
Libera Photon
How complex is the Libera LLRF system to use?
We eased the use of the instrument by providing GUI where all the parameters to operate the Libera LLRF are available. For instance, at EMMA (proof of concept NS FFAG accelerator that uses probably the most complex Libera LLRF configuration) the transition to the RF experts was done within a day, while they were then able to transfer it to the scientists within a few shifts of EMMA operation.
Also when testing the unit at different accelerators, we were able to set it up within a day, so installation itself is not so demanding as well.
Can we optimize control algorithms ourselves?
For each user so called development kit can be prepared. With it either optimisation or complete change of the control algorithm can be made by experienced user.
We are experiencing heavy beam loading during the operation. Is this possible to compensate?
If normal control loop (classical feedback) is not suficient to do the job, we have possibility to employ several other principles – classical rectangular shape of the feed-forward signal, arbitrary shape of the feed-forward signal or even arbitrary shaped feed-forward signal that changes its parameters from pulse to pulse.
Is it possible to control the Libera LLRF unit from a remote place?
Libera LLRF is a network attached device. It is possible to control it from wherever it is possible to connect to it through the network. GUI is the interface. Can the system be integrated into the EPICS control system?
Libera LLRF is developed in a way to enable integration into any control system. For EPICS interface is already available, for others it is possible to do it.
How complex is to do the measurements in the RF system?
This is trully practially effortless. For each input RF signal, there is a demodulated amplitude and phase available in the physical units. For detailed diagnostics selected part of the signal can be viewed and examined in detail with the stability and power level provided. Along with that the output signal and error signals are available. Beside that also the RF syste characterization tool (similar to vector analyzer) can be integrated into the unit. Resonance frequency can be measured and for instance defects in the coupler placements can be seen. Because of its sampling we were able to detect RF system responses that were not known to the user until then. Also the beam loading effects to the RF signal can be seen.
Can Libera LLRF be used in RF systems that operate in the continuous mode of operation?
Libera LLRF can be used in RF systems that operate in continuous and pulsed mode. For instance the version that supports both modes without stopping the unit has been tested. This can be useful for instance when you are conditioning the cavities in pulsed mode of operation before normal continuous mode of operation.
Can Libera LLRF be used in RF systems that operate in the continuous mode of operation?
Libera LLRF can be used in RF systems that operate in continuous and pulsed mode. For instance the version that supports both modes without stopping the unit has been tested. This can be useful for instance when you are conditioning the cavities in pulsed mode of operation before normal continuous mode of operation.
For what kind of accelerators can Libera LLRF be used?
It can be used practically on any type of accelerator known today. Its flexibility to employ various control algorithms is the answer to this along with the measurement part makes it a really valuable tool for the RF expert and operator.
How can I use Libera Hadron?
The system can be used in a very intuitive way. All you need to do is to connect to the unit to your BPM pickup signals or to a laboratory simulated beam signals, plug the network cable and access the system through any machine in network. The Libera Basic Application Support Environment provides several tools in order to enable immediate and unified access to the instrument functionality. Libera Hadron can be in few minutes integrated with several working environment like Matlab, Octave, web services, Microsoft Office... etc...Libera BASE provides a immediate access to many signal processing parameters, provides the access to the acquired data from more or less any development environment.
How does Libera Hadron look like?
Libera Hadron in developed on uTCA based 19“ 2U platform chassis. The system integrates distributed FPGA and Computing Module processing power. The chassis can populate up to 4 BPM modules in order to acquire simultaneously the position from 8 BPM planes. The instrument consists of a high performance stabilized RF front-end and state-of-the-art analog to digital converters. The digital signal processing is implemented on Virtex_5 FPGA and a computing module that can access to large data buffers (up to 8 Gbits per BPM) through a PCIe bus. The data acquired by the BPM modules can be transferred through dedicated low latency LVDS links to FPGA based real time DSP modules for further processing and SFP streaming for feedback purposes.
What kind of data paths are supported by Libera Hadron?
Libera Hadron supports continuous data streams and on demand acquisitions. The provided on demand acquisition include raw data, Single Pass - Single Bunch position and charge measurements and Turn by Turn rate measurements. The system provides Fast Acquisition - Fast Feedback streams (typically 10 kHz data rate streams with the possibility of increasing the rate) and Slow Acquisition (typically 10 Hz) stream use mainly for monitoring purposes. The system can be customized in order to deliver other data streams required by the user, like individual bunch beam arrival time measurements and bunch map representations of individual bunches. The system can be also upgraded in order to apply low latency feedback on individual bunches.
How does Libera Hadron work?
Libera Hadron takes the BPM electrode signals, applies analog and digital signal processing in order to optimally measure the response to individual bunches. The individual bunch positions are collected and presented through the available data paths.
What is Libera Hadron?
Libera Hadron is a BPM signal processing system specially developed for heavy particles circular machine applications. The system provides high resolution single bunch position measurements.
I want to install local feedback in the beamline. Is it possible?
Libera Photon provides data to the Control System but also through real-time I/O ports (SFP slots). One can decide, which data to use. We suggest to use so called FA data, which is streamed out SFP slots and can be grouped within multiple Libera instruments. The benefit is that the data is fully synchronized and can be easily read out with standard PC or sophisticated server.
I want to use Libera Photon in combination with electron BPMs in the storage ring. How can I synchronize acquisitions?
Libera Photon has the Trigger input. The acquisition can be done on-trigger. Furthermore, if Libera Electron/Brilliance/Brilliance+ instruments are installed in the storage ring, the full synchronization can be done using MC input (Machine Clock). In this case, Libera Photon can operate also in offset-tuned conditions.
I have 2-blade sensor configuration (vertical position only). Does Libera Photon support such configuration?
Yes, there are 3 calculation formulas implemented (selectable): X/Y position and Y1/Y2 positions (one of them is log).
How can I interface to Libera Photon? Currently, I use Matlab.
One of the connecting possibilities is also Matlab. The access is done through ssh connection. In case Linux OS is used, the remote access is possible (much faster). On the other side, EPICS or Tango is recommended. In case of EPICS, we provide EDM screens to control the unit.
Can I use Libera Photon in the user station at the end of the beamline?
Yes, as long as the sensors have proper output.
I have to change the gap frequently. Does Libera Photon support gap changes or how can this be handled?
The scale parameters (coefficients, offsets) can be set by the Control System as the gap changes. Alternatively, predefined settings can be stored locally in the instrument. When gap changes, Control System shall send the notification about the gap value.
My sensors have significant dark (leakage) currents. How do they affect the measurement?
If needed, Libera Photon can eliminate the dark current from the position calculation formula.
Can Libera Photon work with positive and negative currents?
Yes.
Can I still use external BIAS source for my sensors?
Yes, Libera Photon can work also with external BIAS source. The correct connection scheme is described in Technical Specifications and User Manual.
Is Libera Photon compatible with my sensors?
Libera Photon is compatible with current-output sensors. The maximum currents can be up to 1.85 mA per channel.
Which models of SFP GbE modules can be used for FA data acquisition?
The list of tested SFP modules:
- Avago HBCU-5710R
- 3COM 3CSFP93
- Finisar FCLF-8520/8521-3
Can the data between Liberas be exchanged?
Yes. Data exchange (or grouping) is typically done in the fast orbit feedback application. Libera Electron and Brilliance have SFP slots in the front panel (first four from the left), that are used for this application. Libera Brilliance+ can optionally be equipped with FGOFB module, that does the same but with more flexibility than Libera Electron and Brilliance. Software wise, instruments must be equipped with FOFB feature.
How precise should the operating environment for Liberas be temperature stabilized?
Usually, it is good enough to control the temperature in +/- 1° C range. The airflow should not be applied directly to the instruments. Take into account the RF cables, which are also sensitive to temperature changes.
What is the meaning of the Machine Time (MT)?
The initial value of the MT (when doing the synchronization) is not important. When one have multiple units synchronized, the MT value must be the same on all units (1 sample difference is allowed). If the MT is not the same on all units, units are not fully synchronized.
The beam does not arrive on multiple Libera units at the same time. How is it possible to adjust the on-trigger acquisition to see the beam on all units?
The easiest way is to use the Trigger delay, which must be set manually for each unit individually. It is only possible to delay the Trigger (not +/- in time). The setting is done with 1 ADC sample resolution.
What is the difference between “internal” and “external” switching source?
The switching frequency (~13 kHz) is obtained only by integer division of the revolution frequency (as Libera sees it). In case one is offset-tuned (detuned) and does not have a fully filled ring, the switching does not exactly follow the actual accelerator revolution frequency. The result is a very low beat frequency in the range of 0 to 20 Hz, depending on the amount of detuning. With CW there is no beating of course. This is called "internal" switching.
One can choose to lock the MC PLL to the externally delivered MC instead. By locking the switching to the MC (with the same division factor) one avoids the beating, since it is always in phase with the filling pattern of the accelerator. This is called "external" switching.
What is the typical data bandwidth in Turn-by-Turn mode on Libera Electron/Brilliance/Brilliance+?
It is approximately 0.35 times the revolution frequency.
How can I measure first turns with Libera Electron/Brilliance/Brilliance+?
The best and easiest way is to use turn-by-turn data acquired on injection trigger. Certain offset can also be applied in order to retrieve the most interesting part of the event.
What if Libera Electron/Brilliance/Brilliance+ PLL is not locked due to heavy detune (e.g. 499.5 MHz instead of 499.654 MHz)?
The instrument will still be working but one should keep in mind the conditions.
How precisely should RF frequency be determined in the Libera Electron/Brilliance/Brilliance+ specification?
Usually, the central RF frequency should be given to us with 1 kHz precision. But the RF frequency may vary in the range of ~20 kHz. Libera is able to follow a variation of +-45 kHz at 500 MHz (+-90 ppm).
Is it possible to use Libera Electron/Brilliance/Brilliance+ in light and collide mode?
Yes, it is possible. But most probably, this will require two different designs, which can be relatively easily exchanged (software only).
Can the same Libera Electron/Brilliance/Brilliance+ unit be used in the storage ring and booster?
Yes, but the software design must be properly installed. In case of Libera instruments produced before year 2011, the instrument should have proper oscillators mounted. Instruments, bought from 2011 on, the reconfiguration is only in software.