AdvancedTCA excitement: Nuclear particle variety

Deutsches Elektronen Synchrotron (DESY) in Hamburg, Germany is a large scientific research center focusing on photons and particle physics. Each year about 3,000 scientists from 40 nations come to Hamburg and join 1,900 resident staff to do scientific research. DESY also has a facility in Zeuthen, south of Berlin, Germany. DESY is involved in many international projects like LHC at CERN, Geneva and IceCube (the world’s largest particle detector) in Antarctica near the South Pole (see related article in VME and Critical Systems magazine).

DESY, in cooperation with the Universities of Cracov, Lodz, Swierk, and Warsaw (all in Poland), has developed a number of AdvancedTCA and AdvancedMC boards in-house for use in the European X-Ray Free Electron Laser project (XFEL) at the DESY site in Hamburg. The AdvancedTCA systems represent the Low-Level Radio Frequency (LLRF) control system within XFEL. Part of XFEL is set up as a mathematically right-handed undulator. Figure 1 illustrates the principle of an undulator as used for XFEL.

Figure 1

Electrons generated by a superconducting particle accelerator are made to deviate from a straight-line forward movement into an undulating (wavy) pattern by flying past opposite polarity magnet elements, an activity that produces intense laser-like radiation in narrow energy bands.

Figure 2 (click graphic to zoom by 1.9x)

For the final project around 100 AdvancedTCA and 1,000 AdvancedMC boards (Figure 2) are needed. AdvancedTCA and AdvancedMC are not standardized for industrial or scientific research applications using real-time interrupts, ADCs, DACs, and trigger signals, so DESY designed the boards in-house (see Figure 3). Live demonstration of a complete system took place in January 2009. A prototype system had been tested on the Free electron LASer in Hamburg facility (FLASH) about a year ago. Figure 4 shows the test setup of an AdvancedTCA carrier board, AdvancedMCs (two from TEWS), and Rear Transition Module (RTM).

Figure 3 (click graphic to zoom by 1.6x)

Figure 4 (click graphic to zoom by 1.9x)

These projects employed commercial AdvancedTCA and AdvancedMC boards from ADLINK and TEWS as well as card cages from ELMA and Schroff.

Nuclear particles are excited and power-amplified from a low-power (hence low-level) source in the radio frequency range (1.3 GHz in XFEL). The LLRF control sets the RF frequency and phase reference, timing, and feedback control. It includes exception handling, monitoring, transient detection, and interfaces to other subsystems. LLRF must support approximately 100 ADC measurement channels and an equal amount of DAC control channels with significant data processing capability. Moderate levels of radiation must be tolerated, and all cabling must be done on the rear side using RTMs where needed.

The software sets LLRF parameters, controls servers and clients, and makes a Finite State Machine (FSM) available for the LLRF control system. About 50 percent of the LLRF system cost will be in software. It shall not produce more than one LLRF station failure per week, and it must maintain accelerating fields for up to 32 cavities within given tolerances.

For more information, contact Hermann at hstrass@opensystemsmedia.com.

All figures are courtesy DESY.