# US 10,529,536 B2 · Electron beam generation for transmission electron microscope

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- Number: US 10,529,536 B2
- Document ID: US10529536B2
- Status: Granted
- Kind: B2
- Application number: 15/769,170
- Filed: 2016-10-20
- Published: 2018-10-18
- Granted: 2020-01-07
- Earliest claimed: 2015-10-20
- Assignees: Technische Universiteit Eindhoven
- Applicants: Technische Universiteit Eindhoven
- Inventors: Otger Jan Luiten
- Web page: https://patentgrep.com/patent/US10529536B2

## CPC

- H01J 37/285: Emission microscopes, e.g. field-emission microscopes
- H01J 37/06: Electron sources; Electron guns
- H01J 37/063: Geometrical arrangement of electrodes for beam-forming
- H01J 37/073: Electron guns using field emission, photo emission, or secondary emission electron sources
- H01J 37/26: Electron or ion microscopes; Electron or ion diffraction tubes
- H01J 2237/083: Beam forming
- H01J 2237/2626: Pulsed source
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

In one aspect, the present invention provides a method of generating an electron beam in a transmission electron microscopy device. The method includes: generating an electron pulse [306] by a pulsed electron source [300], accelerating the electron pulse in a first resonant microwave cavity [302], passing the accelerated electron pulse through a drift space [314], and correcting the energy spread of the accelerated electron pulse in a second resonant microwave cavity [304] by operating it out of phase by 90 degrees from the first resonant cavity [302].

## Claims

### Claim 1

A method of generating an electron beam in a transmission electron microscopy device, the method comprising:
generating an electron pulse by a pulsed electron source;
accelerating the electron pulse in a first resonant microwave cavity;
passing the accelerated electron pulse through a drift space; and
correcting an energy spread of the accelerated electron pulse in a second resonant microwave cavity by operating the second resonant microwave cavity out of phase by 90 degrees from the first resonant cavity.

### Claim 2 (depends on 1)

The method of claim 1 wherein accelerating the electron pulse in the first resonant microwave cavity comprises passing the electron pulse through a booster cavity followed by a decompression cavity, operating the decompression cavity out of phase by −90 degrees from the booster cavity and operating the decompression cavity out of phase by 180 degrees from the second resonant cavity.

### Claim 3 (depends on 1)

The method of claim 1 wherein generating the electron pulse by the pulsed electron source comprises delivering the pulse in phase with an oscillation of the fields in the first resonant microwave cavity.

### Claim 4

A device for generating an electron beam, the device comprising:
a pulsed electron source configured to generate an electron pulse;
a first resonant microwave cavity configured to accelerate the electron pulse;
a second resonant microwave cavity configured to correct an energy spread of the accelerated electron pulse;
a drift space separating the first resonant microwave cavity from the second resonant microwave cavity;
a phase shifter connected to the first resonant microwave cavity and the second resonant microwave cavity, configured to adjust an RF phase difference between the first resonant microwave cavity and the second resonant microwave cavity to a value substantially equal to 90 degrees.

### Claim 5 (depends on 4)

The device of claim 4 further comprising a RF power supply that feeds RF power into both the first resonant microwave cavity and the second resonant microwave cavity.

### Claim 6 (depends on 4)

The device of claim 4 further comprising a decompression cavity positioned between the first resonant microwave cavity and the second resonant microwave cavity.

### Claim 7 (depends on 6)

The device of claim 6 further comprising a second phase shifter configured to adjust an RF phase difference between the decompression cavity and the first resonant microwave cavity and a third phase shifter configured to adjust an RF phase difference between the decompression cavity and the second resonant microwave cavity.

### Claim 8 (depends on 7)

The device of claim 7 wherein the second phase shifter is configured to adjust the RF phase difference between the decompression cavity and the first resonant microwave cavity to a value substantially equal to −90 degrees.

### Claim 9 (depends on 8)

The device of claim 8 wherein the third phase shifter is configured to adjust an RF phase difference between the decompression cavity and the second resonant microwave cavity to a value substantially equal to 180 degrees.

### Claim 10 (depends on 4)

The device of claim 4 wherein the drift space has length L larger than a total cavity length.

### Claim 11 (depends on 10)

The device of claim 10 wherein the drift space has length L at least 10 cm.

### Claim 12 (depends on 11)

The device of claim 11 wherein the drift space has length L=40 cm.

### Claim 13 (depends on 4)

The device of claim 4 wherein the first resonant microwave cavity is a cylindrically symmetric TM010 pillbox cavity.

### Claim 14 (depends on 4)

The device of claim 4 wherein the first resonant microwave cavity comprises three stacked cylindrically symmetric TM010 pillbox cavities.

### Claim 15 (depends on 4)

The device of claim 4 wherein the second resonant microwave cavity is a cylindrically symmetric TM010 pillbox cavity.