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Measuring and controlling, in real time, the position of bulk components to absorb energetic particles out of the nominal beam core with high reliability and accuracy at the world’s most powerful particle accelerator, the Large Hadron Collider (LHC).
Using the NI LabVIEW Real-Time and LabVIEW FPGA modules, NI SoftMotion Development Module for LabVIEW, and NI R Series reconfigurable I/O PXI hardware to develop an FPGA-based motion control system to intercept misguided or unstable particle beams.
LHC Expected to Answer Fundamental Questions about the Universe
Superconducting magnets control the trajectory of the beams, which contain enough energy to melt 500 kg of copper.
The European Organization for Nuclear Research, CERN, uses particle accelerators to crash beams of ions or protons together and into other targets to recreate the conditions that existed during the formation of the universe. Superconducting magnets in a superfluid helium bath at 1.9 K (-271 °C or -456 °F) control the trajectory of LHC beams, which have enough energy to melt 500 kg of copper.
Control System Reliability Is Critical
A beam that travels off its course can cause catastrophic damage to the collider, so reliability is critical. To prevent particles from straying, we are installing more than 100 collimators. Collimators use blocks of heavy materials to absorb energetic particles out of the beam. They are controlled with reconfigurable I/O modules mounted in two separate National Instruments PXI chassis for redundancy totaling 120 PXI systems. One chassis controls up to 15 stepper motors mounted on three different collimators through a 20-minute motion profile to align the blocks, and a second chassis checks the real-time positioning. In phase II of the project, we plan to add about 60 more collimators and use a total of about 200 PXI systems.
Both PXI chassis run LabVIEW Real-Time on the controller for reliability and LabVIEW FPGA on the reconfigurable I/O devices in the peripheral slots to perform the collimator control. We use the NI SoftMotion Development Module and NI reconfigurable modules to quickly create a custom motion controller for approximately 600 stepper motors with millisecond synchronization over the 27 km of the LHC. The FPGAs on these devices give us the level of control we need. We selected the LabVIEW and PXI solution for the small size, ruggedness, and cost savings over the traditional VME and programmable logic controller-based model.
LHC begins operation in summer 2008. Scientists and researchers worldwide are excited to use LHC to explore the building blocks of the universe.
– Robert Losito
This article first appeared in the Q2 2008 issue of Instrumentation Newsletter.
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