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OPs-2xx: RF Systems

OP-210: High Power RF System

The high power RF (HPRF) system has 27 RF stations consisting of a modulator, pulse cables and pulse transformer, klystron, waveguide distribution system, interlock system, several power supplies, pre-amplifier and other auxiliaries in racks to provide RF power to the super conducting (SC) accelerator modules in the XFEL. The injector is served by 2 RF stations, the linac tunnel XTL has 25 RF stations, each providing RF power for 4 SC modules.

  • Operation, maintenance and repair of the HPRF components in the tunnel, the modulator hall XHM and for the module and cavity test stands in the AMTF.
  • In particular the klystrons are consumable equipment with a limited life time. It is currently assumed based on the specs of the devices and experience from flash that 3 klystrons per year need to be tested and replaced.
  • Operation and maintenance of the klystron test stand and the wave guide assembly and test facility,

OP-215: Low Level RF

The Low Level Radio Frequency (LLRF) Control of the European XFEL accelerator is indispensable for the operation of the accelerator since the system is setting and maintaining stable acceleration voltage and phase of the high-precision calibrated vector-sum of individual RF stations. Without reaching the specified performance no lasing of the European XFEL can be expected.

  • The XFEL LLRF guarantees an overall RMS field stability of better than 0.01% in amplitude and 0.01° in phase at the 1.3 GHz cavity operating frequency.
  • The LLRF system provides also a highly stable RF reference along the accelerator tunnel used to calibrate signals. Three different master oscillators provide reference at a total of 250 taps; 70 active stabilization units are involved.
  • The LLRF system is driving all klystrons of the facility. Thus it regulates a total of 27 superconducting linac sections consisting of 32 accelerating structures each, and 2 normal conducting transversely deflecting structures in the bunch compressors.
  • The longitudinal feedback system is also part of the LLRF control.
  • A total of 55 electronics crates with 1200 boards and 200 external units are operated for the LLRF control.

OP-220: Accelerator Modules

OP-220 deals with all accelerator module related issues. Cryogenic operation of the cryostats and interconnects but also cavity, RF power coupler, and frequency tuners are taken care of. The repair of modules including partly disassembly and reassembly are addressed. Also three spare modules within 10 years of operation are included.

  • Supervision of the RF operation of all installed accelerator modules; the almost 800 superconducting cavities and the attached RF power couplers need monitoring and occasional performance check.
  • The 24/7 operation of the European XFEL requires long-lasting support of the shift crew; on-call duty is organized to support the RF operation.
  • The almost 800 RF power couplers require regular maintenance and, if necessary, repair; also the technical interlock system of the couplers with its specially developed electronics needs supervision and maintenance.
  • The cryogenic operation of the accelerator modules needs support from the respective expert team. Monitoring of the cryogenic load during operation and as a function of time is to be done.
  • Each accelerator module houses a superconducting quadrupole package. Monitoring of the operation is part of OP-220.
  • Repair and testing of modules left over from the XFEL construction phase is to be done. The work will happen in the first operation years.
  • During the first 10 years of operation the procurement/fabrication/testing of three new modules is foreseen.

OP-225: Cryogenics

The super-conducting accelerator of the XFEL is operated at 2° K with liquid Helium (He) being provided by the DESY cryogenic plant (the refurbished plant of the HERA collider). The cryogenic plant and associated systems provide the cooling power for the 1.3 GHz super-conducting cavities and super-conducting focussing magnets in the accelerator modules. The tasks of the OP-225 will be the following:

  • 24/7 operation of the DESY cryogenic plant in part through a contract with an external company
  • maintenance and repair of the European XFEL related part of the DESY cryogenic plant (in part through a contract with an external company
  • supervision of the external operational company
  • operation, maintenance and repair of the cryogenic distribution systems to the XTIN, XTL and AMTF (as needed for European XFEL related purposes)
  • management of gaseous He supply including volume control and re-stocking

OP-230: 3.9 GHz System

The 3.9 GHz System consists of the 3rd harmonic acceleration module and the corresponding RF station consisting of a modulator, pulse cable and pulse transformer, klystron, waveguide distribution system, interlock system and other auxiliaries in racks. The task of this OP is the
Operation, maintenance and repair of the 3.9 GHz HPRF components in the injector tunnel and injector shaft and for the module test stand XATB1 in the AMTF.

OP-235: TDS (Transverse Deflecting System)

The TDS RF System consists of the Transversely Deflecting Structures in the injector and bunch compressor 1 and 2, the corresponding klystrons, waveguides and modulators. The system in BC1 is currently not available and has to be installed during a shutdown in the future. In the operation phase, the tasks of the OP-235 will be the following:
Operation, maintenance and repair of the TDS systems in the injector tunnel (XTIN), injector shaft (XSE) and linac tunnel (XTL)


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