• K.P. Przygoda, A. Napieralski, T. Pozniak
  TUL-DMCS, Łódź
• M.K. Grecki
  DESY, Hamburg

DESY FLASH ac­cel­er­a­tor is com­posed of 6 ac­cel­er­at­ing mod­ules. The sin­gle ac­cel­er­at­ing mod­ule con­tains 8 su­per­con­duct­ing res­o­nant cav­i­ties. Since FLASH op­er­a­tion is ded­i­cat­ed for var­i­ous en­er­gy physics ex­per­i­ments such as high cur­rent beam ac­cel­er­a­tion or SASE tun­ing, the sc cav­i­ties are Lorentz force de­tuned when op­er­at­ed with high gra­di­ent ac­cel­er­at­ing fields*. The ACC 3, 5 and 6 cry­omod­ules are equipped with piezo tuners allow com­pen­sat­ing of dy­nam­ic de­tun­ing dur­ing the RF pulse. In order to as­sure the si­mul­ta­ne­ous con­trol of all avail­able piezo tuners a dis­tribut­ed, mul­ti­chan­nel dig­i­tal and ana­logue piezo con­trol sys­tem was ap­plied. The paper de­scribes the main parts of the sys­tem as well as its ef­fi­cien­cy mea­sure­ments ob­tained dur­ing high cur­rent beam ac­cel­er­a­tion (9 mA tests) per­formed in DESY. The piezo tuners were op­er­a­ble for 23 cav­i­ties for sev­er­al hours. More­over, the first piezo sen­sor mea­sure­ments using dou­ble stack piezos in­stalled in ACC 6 cry­omod­ule are briefly demon­strat­ed.

*M. Grecki, A. Andryszczak, T. Poźniak, K. Przygoda, S. Sękalski,
"Compensation of Lorentz Force Detuning For SC Linacs (With Piezo
Tuners)", Proceedings of EPAC 2008, pp. 862-864.