The first block after the steering magnet is the collimator entrance. This will trace and measure the beam profile for right and left tuning . The collimator is cooled by water and will have a maximum rated current of approximately 250uA on each side. If the beam is more than 250uA the PLC will decrease the ion source of the cyclotron to a lower current mode to avoid a catastrophe! Below the collimator (see picture above) is a diffusion pump and a mechanical pump which produces a beam line vacuum of 1.0 10-6 mbar. An identical  pump assembly is also located at  the end of the beam line.      Next to the collimator is the quadrupole  magnet. This device focuses the beam into a very dense beam spot of approximately 3mm in diameter. The center of the quad produces a magnetic field of 3500 gauss. The current and voltage in the coil (water cooled) will be 90A and 20vdc   which is also regulated by the PLC. When the stream of  negative ions exit the magnetic field of the cyclotron, it has the tendency to divert in the horizontal plane because of  the strong magnetic field of the switching magnet. The first quadrupole will correct this "offset" divergence in the horizontal axis.  =>H<= The second quadrupole will converge the beam in the vertical axis offset created  from the first quad. The third quadrupole performs horizontal focusing .