collimated to limit the maximum angle of the beam to 1 degree and the maximum diameter to 1mm at the sample.
The beam, after passing through the Extraction Gap is then focused onto the Pulsing and Mass Analyzing Aperture by the first Einzel Lens. The large diameter lens assures high quality ion optical qualities of the beam with minimal spherical aberration. The beam is also acted on by the Pulsing System which deflects the beam across the aperture resulting in short pulses of beams. As the beam passes through the Crossed Field Analyzer (Wien Filter) it is mass analyzed so that only the wanted ion species continues through the system. Emerging from the aperture is a pulsed beam with pulse widths less than 10 nanoseconds (as low as 5 nanoseconds) and a peak current of 0. 1 to 1 microamperes. Countdown circuitry permits pulse repetition rates over a wide range (5 to 20 kHz). This beam is diverging after being focused through the first aperture, so a second Einzel Lens is used to focus the beam at the sample position in the customer's scattering chamber.
Immediately after the second Einzel Lens is a 3 Degree Neutral Beam Deflector which eliminates any neutral particles from continuing on to the target position. The exit flange of the system is designed to mate to the entrance of the Purchaser's Analytical Chamber.
The system is designed to be UHV compatible. Two stages of differential pumping prevent any significant gas load from the source from reaching the sample chamber.
Ion Species: H, He,
Mass Analysis: ExB Wien Filter
Energy Range: 3 to 25 keV
Energy Spread: <50 eV
Pulse Performance (for H+, He+ ions at 10 keV):
Pulse Width: < 10 nS (5 nS design)
Pulse Rep Rate 10 to 30 kHz
Average Beam Current: 10 to 100 pA (based on 0.1 to 1.0 microamp d.c. current before pulsing)
Spot Diameter: 1 mm at target position
UHV Compatible: 2 stage differential pumping
All power supplies, controls, metering and monitoring are contained in a self-standing protective consoles located near the ion beam line.
The beam pulsing system consists of two sets of deflection plates mounted orthorgonal to one another, a sinusoidal voltage generator, binary count-down electronics for selecting pulse repetition rates and a beam chopping aperture.
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