The unique design of the NEC beam profile monitors (BPM) has made them among the most popular and reliable beam diagnostic instruments available. NEC has provided over 2,000 BPMs worldwide. The NEC BPM reliably gives accurate information concerning the ion beam cross-section for ion beams with currents as low as 1nA for most models. Our newest model can monitor currents in the fA range.
The NEC BPM system is ideally suited for applications that require instantaneous scope display of beam cross-sectional shape and position without significantly interrupting beam transmissions. Particle beams of electrons, ions, or energetic neutrals are monitored.
The unique patented design of the NEC BPM relies on the collection of secondary electrons from a grounded scanning wire. This arrangement eliminates contact noise at the rotating scanning wire.
A helical wire sweeps across the beam twice during each revolution to give a Y profile in a half revolution and an X profile during the next half revolution. A cylindrical collector around the grounded wire collects beam-induced secondary electrons from the wire to provide a signal proportional to the intercepted beam intensity at every instant. This signal is then sent to the NEC controller and to an oscilloscope for direct viewing of the beam profile.
There are four models of BPMs, with various versions of each model. Below is a brief description of each model.
Original BPM and most popular model.
Designed to handle large diameter ion beams
Ideal for use when beamline length is at a premium
Ideal for use when beamline length is at a premium and a larger diameter beam is involved
The standard BPM system will routinely monitor beams with current densities to 10nA/cm2. NEC has recently developed a low current BPM with a minimum detectable beam current in the FemptoAmp range. Please contact NEC for further information.
NEC also offers controllers for the above BPMs. Three models are available:
Model FP3A: single unit controller for local control
Model SS5A: multi-unit controller for local control. Can control up to 12 BPMs.
Model SS6: multi-unit controller for computer control. Can control up to 12 BPMs.