EuCARD >> News >> Newsletters >> Issue 6 >> Article 3
 


Hamburg in a FLASH
   

This summer, FLASH - the Free-electron LASer in Hamburg - produced laser light with a record wavelength of 4.45 nanometres thanks to machine upgrades. But how is EuCARD helping to improve the laser's performance?

FLASH, the world’s first X-ray free-electron laser has been available to the photon science user community for experiments since 2005.

Record wavelength success

In June 2010, DESY's free-electron laser managed for the first time to produce laser light with a wavelength of 4.45 nanometres, beating the previous record of 6.5 nanometres. In addition, the peak intensity of single light pulses nearly doubled, with 0.3 millijoule.

    


An aerial photo of the experimental hall for FLASH - the Free-electron LASer in Hamburg. Image courtesy of DESY. Thumbnail image main page shows electromagnetic fields accelerating electrons in superconducting resonators. Image courtesy of DESY.
 
 


Spectrum of the record laser pulse peaks at FLASH of a wavelength of 4.45 nanometres. Image courtesy of DESY

     

This event followed a five-month machine upgrade. A seventh superconducting accelerator module was added to increase the maximum electron energy to 1.2 Giga-electronvolts (GeV). In addition, to improve the quality of the accelerated electron bunches, a special 3.9-GHz module was installed. These additions were both seen as prototypes for the European XFEL project, their success is also an important milestone for XFEL.

"It is absolutely impressive how fast and promising FLASH is operating after such a substantial upgrade," congratulated Reinhard Brinkmann, director of the DESY accelerator section.

Record wavelengths lower than 4.45 nanometres are expected soon.
 
 

Low Level Radio Frequency (LLRF) at FLASH - EuCARD's contribution

The upgrades mentioned above are just some of the improvements to FLASH, but more are foreseen. For example, EuCARD researchers are currently developing a new Low Level Radio Frequency (LLRF) control system. The current control system, though operational, needs improvements in field regulation, availability, maintenance and operability to fulfill user needs over the next 10 years.

The planned LLRF control system upgrade uses technology based on Telecommunications Computing Architecture (xTCA), which is being specially adapted to include the instrumentation needed for High-Energy Physics experiments.

The input signals require processing by AMC plug-in modules, which are being developed using state-of-the-art processes to optimize costs while keeping high commercial standards on reliability, availability, maintainability etc. Several components of the LLRF system (such as the controller, distribution of reference frequency, radiation monitoring) and control software were partially developed within the CARE project, these are now being extended and implemented within EuCARD.

Progress so far

"We are well advanced in design and manufacturing of the new LLRF system", explains Mariusz Grecki, task leader of LLRF at FLASH within EuCARD.

"The first revision of AdvancedTCA carrier board (prototype) has been designed, manufactured and debugged."

"Multiple tests of commercial downconverter modules have been performed. Problems with inter-channel crosstalks have been identified and special PCB design for multi-coax connector has been developed and implemented in the system."

 

"The Vector Modulator and Timing modules (AMCs) have been debugged and successfully tested."

"The piezo controller compatible with xTCA based system has been designed and manufactured and is being debugged."

"The AMC module for gamma and neutron radiation monitoring has been designed and is being produced. The strategy for beam feedbacks has been prepared. As a final solution, dedicated board in AMC form factor will be designed and manufactured."

 



The AMC vector modulator board. Image courtesy of Mariusz Grecki, DESY
 
 

"A large amount of work has been done in the area of the software development. A DOOCS (local control system) server has been rewritten. FPGA firmware code has been simplified and improved, and several bugs have been removed."

"We are now preparing tests of second revision of the system with the aim on demonstrating system performance."

"The collaboration works so efficiently thanks to EuCARD support."

- Kate Kahle, CERN, EuCARD-DCO (WP2); Mariusz Grecki, DESY, EuCARD-SRF (WP10)
           

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