Recent developments based on PICMG xTCA for Physics standards

1The xTCA for Physics PICMG standards work began in 2009 after several years of investigation into the suitability of ATCA as a controls platform for several new accelerators then under consideration.

The largest of the accelerators, now known as the International Linear Collider (ILC), is a 20-mile long machine (costing over $10 billion) that is still under consideration by several governments, most prominently the Japanese, who are proposing to host the proposed multinational machine which has been under development for more than a decade.

Smaller new machines using similar technology are also very active. The main one is the new DESY (Deutsches Electronen Synchroton) lab in Hamburg’s new X-Ray Free Electron Laser (XFEL), about a tenth the length of the ILC. This machine is adapted to photon physics research using pulsed electron beams to produce very short X-ray beam pulses to open up new fields of materials research. This machine is now built and beginning the commissioning stage, as discussed below by Kay Rehlich; Kay headed the control system development based on a new variant of MicroTCA called MTCA.4, plus a more recent version called MTCA.4.1, which includes an auxiliary backplane to manage the very high precision of fadio frequency (RF) controls demanded by these machines. Two other machines (described below by Andrew Young of the SLAC National Accelerator Laboratory) benefitting from these new standards are the Pohang Light Source in South Korea, and the European Spallation Neutron source in Lund, Sweden.

MTCA implementation at the DESY XFEL (Kay Rehlich)

The European XFEL is a 3.4 km (2.1 mile)-long X-ray free electron laser (XFEL) currently in the commissioning phase. The 1.7 km (1.05 mile)-long accelerator can raise electrons to 17.5 GeV energy. It is followed by undulator sections to generate extremely short X-ray flashes with wavelengths in the rage of 0.05 to 4.7 nanometers so that even atomic details become discernible. [Note: An undulator is a long section of alternating polarity magnets that “wiggle” the electron beam, causing it to radiate straight ahead X-ray pulses which are the beam of interest for research; the electrons are then stripped off by a bending magnet into a beam dump.]

This 1.2 billion Euro ($1.28 billion) facility was constructed and financed by 11 European countries with a major contribution from DESY in Hamburg. MTCA is used for all of the important superconducting cavity accelerator sections to establish highly precise phase and amplitude of the beam from cavity-to-cavity for the full length of the machine.

The electron accelerator can produce up to 27,000 electron beam bunches per second. These bunches are distributed to three undulators to deliver beam to three experimental areas operating simultaneously by switching magnets. A MicroTCA-based timing system and machine-protection system provides a flexible, safe, and independent operation of the three beam lines. All fast subsystems to read out and control the RF, the beam, and the interlocks are implemented in MicroTCA.4 standard. In almost 800 superconducting accelerating cavities, the amplitudes and phases are measured and controlled with a stability of 0.02 ps. The MTCA.4 standard provides the required high analog performance and fast communication channels to implement this cutting-edge technology; it also supports the full remote management of this entire distributed installation. More than 200 MicroTCA.4 shelfs are installed and operational to control the accelerators and experiments.

MTCA at the Pohang Accelerator Laboratory (PAL) XFEL (Andrew Young)

The Pohang Accelerator Laboratory (PAL) in Pohang, South Korea, has developed a 0.1 nm SASE-based FEL, PAL-XFEL, for a high power XFEL. The $400 million XFEL has successively installed a linac, undulator, and beam line and was completed at the end of 2016. The FEL commissioned the hard and short pulse X-ray coherent photon sources with an MTCA.4 peam position monitor (BPM) and timing distribution system. The BPM system consists of 23 MTCA.4 shelves that provide positioning and intensity of the beam for over 200 BPMs. The system consists of stripline BPMs for the linear accelerator, which has a resolution of 2µm at 180pC (picocoloumbs). A second BPM system was a cavity BPM system used in the undulator section which has a resolution of 250nm at 180pC.

The MTCA.4 standard provides the required high analog performance and fast communication to implement this cutting-edge technology. The BPM system supports beam synchronous data management though the EPICs control system which enabled the system to be fully commissioned in a very short time period.

MTCA at the European Spallation Source (Andrew Young)

The European Spallation Source (ESS) is a 5MW spallation source under construction in Lund, Sweden, with a 2Gev proton beam that will deliver 2.86ms proton pulses at a rate of 14 Hz to a rotating tungsten target. This machine is a 1.8 billion Euro ($1.92 billion) project with an in-kind contribution of 40 percent. The machine will provide advancements in medical, energy, smart materials, and neutron science.

The ESS accelerator will use MTCA.4/4.1 for the BPM and Low Level RF (LLRF) systems. There will be over 150 shelves that will use a new high speed digitizer with a Xilinx Kintex UltraScale device (designed by Struck in Germany). The new rear transition module for both BPMs and LLRF was designed by SLAC/DESY and licensed to Struck to operate over a wideband of frequencies ranging from 352 MHz to 1.3 GHz. The ESS accelerator will begin commissioning in 2018.

Status of xTCA for Physics standards development (Ray Larsen)

The xTCA for Physics collaboration of laboratories and industry under PICMG has now processed three major hardware specifications and two software guidelines, with three further software guidelines still under development, two of which are nearing completion. These are summarized in Table 1 above.

Table 1: xTCA for Physics standards development.
(Click graphic to zoom by 1.9x)

The major contribution to the user community is the addition of powerful rear-transition module options to MTCA.0. Another is in MTCA.4.1, with the addition of an auxiliary backplane with very high RF bandwidth to accommodate many new classes of rear transition modules for both analog and digital high-performance systems.

Community developments

In addition to the above, DESY has spearheaded a collaboration of the laboratory, government, and industry to help drive many of the new lab applications into the marketplace. DESY also hosted the 5th Annual MTCA Workshop for laboratories and industry in December 2016, attended by approximately 150 researchers and industry participants along with exhibitors. Due to this collaboration and steady commitment, it appears that MTCA utilization among research users in Europe, Japan, Korea, and the U.S. is growing.

Ray Larsen is Systems Project Manager, Instrumentation & Controls, at Stanford University’s SLAC National Accelerator Laboratory in Menlo Park, California. Kay Rehlich headed the control system development for DESY in Hamburg, Germany. Andrew Young is an engineer at Stanford University’s SLAC National Accelerator Laboratory in Menlo Park, California.