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Time-of-Flight Electron-Beam Pulse Compression

IP.com Disclosure Number: IPCOM000040915D
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Jenkins, KA: AUTHOR

Abstract

In stroboscopic E-beam testing, it is desirable to use very short pulses of electrons, as short as 10 ps, while running at a 1 ns repetition rate. Present E-beam testers can achieve this by discarding the beam during the unused time but this means a large fraction of the already low intensity beam is wasted.

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Time-of-Flight Electron-Beam Pulse Compression

In stroboscopic E-beam testing, it is desirable to use very short pulses of electrons, as short as 10 ps, while running at a 1 ns repetition rate. Present E- beam testers can achieve this by discarding the beam during the unused time but this means a large fraction of the already low intensity beam is wasted.

With the simple deflection scheme shown in Fig. 1, it is possible to time- compress a pulse of electrons of fixed energy by varying the flight path, thereby changing the arrival time. If the delay is in proportion to the time from the end of the pulse, the entire pulse will arrive simultaneously.

The time delay for an electron of velocity u is

(Image Omitted)

where is the deflection angle and is the undeflected path length. The maximum delay depends on the column length, , and the maximum angle which can be tolerated. A 1 keV electron could be time delayed 100 ps by an 11o deflection over a 10 cm column.

The beam pulse is illustrated by the curve (a) of Fig. 2. The ideal time of flight shift would cause simultaneous arrival of the entire pulse. This would be a sawtooth shift, as illustrated in curve (b) of Fig. 2. The field of the deflecting plates would have the shape suggested in curve (c) of Fig. 2 where the rounding occurs from the cosr term. The plates would need fields no greater than a few hundred volts/cm. At high frequencies, it will be impossible to achieve this ideal deflection, but a large compressio...