Extraction Region

On the opposite side of the ring from the injection straight, the extraction straight is where we get the beam out of the ring once it’s been accumulated. Here a set of 14 very fast magnets turn on in about 200 nanoseconds, a fraction of the time it takes a particle to go around the ring. When these magnets turn on the beam is steered out of the ring and down the transport line to the liquid mercury target. From injection to extraction takes one thousandth of one second, and the whole process repeats 60 times every second!

Two sets of extraction kicker assemblies with a pair of quadrupole magents and a dipole corrector magnet make up the extraction straight region of the accumulation ring at the Spallation Neutron Source.

The extraction kicker assemblies act like an ultra-fast switch for the proton beam in the accumulation ring at the Spallation Neutron Source. They generate a very brief, powerful magnetic pulse that quickly nudges the tightly packed beam out of the ring at precisely the right moment. This allows the beam to be cleanly and accurately sent to the target, where it is used to produce neutrons for scientific research.

The quadrupole magnet assemblies in the FODO line of the Spallation Neutron Source provide alternating focusing and defocusing forces that confine and shape the charged particle beam. Arranged in a Focus–Drift–Defocus–Drift (FODO) pattern, they maintain beam stability, control beam size, and preserve beam quality as the particles are transported efficiently along the accelerator.