Beam Profile Monitors

BPM80

BPM81

BPM82

BPM83

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Product Features

• Can monitor beams up to 2.75″ (6.98cm) in diameter
• Can handle a beam power density of 140W/mm² or more
• Custom mounting flanges and housings available

The unique design of NEC’s beam profile monitors (BPMs) has made them among the most popular and reliable beam diagnostic instruments available, with over 2,000 BPMs provided for customers worldwide. The NEC BPM reliably gives accurate information concerning the 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.

Application

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 can all be monitored.

Design

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 provide a Y profile and X profile in each successive 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.

NEC provides four standard models of BPM, with various versions and options for each model. Below are brief descriptions of each model.

Model BPM80	Original BPM and most popular model Can monitor beams up to 1.0″ (2.54cm) diameter Maximum beam power density of 140 W/mm2 (1kW for 3mm dia. beam) Typically provided in an NEC supplied housing
Model BPM83	Designed to handle large diameter ion beams Can monitor beams up to 2.75″ (6.98cm) diameter Maximum beam power density of at least 150 W/mm2 Typically provided in an NEC supplied housing
Model BPM81	Ideal for use when beamline length is at a premium Can monitor beams up to 1.0″ (2.5cm) diameter Maximum beam power density of 140 W/mm2 Designed for insertion into a customer supplied housing
Model BPM82	Ideal for use when beamline length is at a premium and a larger diameter beam is involved Can monitor beams up to 2.0″ (5cm) diameter Maximum beam power density of 140 W/mm2 Designed for insertion into a customer supplied housing

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.

Accessories

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 (up to 12 BPMs) for local control
• Model SS6: multi-unit controller (up to 12 BPMs) for computer control

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