# US 10,121,627 B1 · Ion pump noble gas stability using small grain sized cathode material

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- Number: US 10,121,627 B1
- Document ID: US10121627B1
- Status: Granted
- Kind: B1
- Application number: 15/794,023
- Filed: 2017-10-26
- Granted: 2018-11-06
- Earliest claimed: 2017-10-26
- Assignees: Edwards Vacuum LLC
- Applicants: Edwards Vacuum LLC
- Inventors: Anthony Wynohrad
- Web page: https://patentgrep.com/patent/US10121627B1

## CPC

- H01J 1/146: with metals or alloys as an emissive material
- H01J 9/042: {Manufacture, activation of the emissive part}
- H01J 9/18: Assembling together the component parts of electrode systems
- H01J 41/20: using gettering substances
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

A method includes assessing a plurality of Titanium plates to determine a grain size for each plate and removing all Titanium plates with an average grain size that is larger than a threshold size from the plurality of Titanium plates. One of the Titanium plates remaining in the plurality of Titanium plates after the removing step is then used to form a cathode for an ion pump.

## Claims

### Claim 1

A method comprising:
assessing a plurality of titanium plates to determine a grain size for each plate;
removing all titanium plates with an average grain size that is larger than a threshold size from the plurality of titanium plates;
using one of the titanium plates remaining in the plurality of titanium plates after the removing step to form a cathode for an ion pump.

### Claim 2 (depends on 1)

The method of claim 1 wherein the threshold grain size has an ASTM grain number of 9.

### Claim 3 (depends on 1)

The method of claim 1 wherein the plurality of titanium plates comprises titanium plates of a single grade.

### Claim 4 (depends on 1)

The method of claim 1 wherein removing the titanium plates with a grain size that is larger than the threshold size decreases a likelihood that an ion pump containing one of the titanium plates remaining in the plurality of titanium plates will incur noble gas instability.

### Claim 5 (depends on 4)

The method of claim 4 wherein removing the titanium plates with a grain size that is larger than the threshold size decreases a likelihood that an ion pump containing one of the titanium plates remaining in the plurality of titanium plates will incur Argon instability.

### Claim 6

A method comprising:
requiring that a cathode plate have an average grain size that is smaller than a threshold size; and
constructing an ion pump from the cathode plate.

### Claim 7 (depends on 6)

The method of claim 6 wherein cathode plates with an average grain size smaller than the threshold size have less frequent noble gas instability than cathode plates with average grain sizes that are larger than the threshold size.

### Claim 8 (depends on 7)

The method of claim 7 wherein the threshold grain size has an ASTM grain number of 9.

### Claim 9 (depends on 6)

The method of claim 6 wherein requiring that a cathode plate have an average grain size smaller than a threshold size comprises requiring that material for the cathode plate be analyzed to determine the average grain size of the material.

### Claim 10 (depends on 6)

The method of claim 6 wherein the cathode is made of titanium.

### Claim 11 (depends on 10)

The method of claim 10 wherein the cathode is made of a single grade of titanium.

### Claim 12

A method comprising:
setting a maximum average grain size for a cathode plate in an ion pump; and
building the ion pump using a cathode plate that has an average grain size that is less than or equal to the maximum grain size.

### Claim 13 (depends on 12)

The method of claim 12 wherein the cathode plate contains titanium.

### Claim 14 (depends on 12)

The method of claim 12 wherein setting the maximum average grain size comprises setting the maximum average grain size to reduce noble gas instability in the ion pump.

### Claim 15 (depends on 14)

The method of claim 14 setting the maximum average grain size to reduce noble gas instability in the ion pump comprises setting the maximum average grain size to reduce Argon instability in the ion pump.

### Claim 16 (depends on 14)

The method of claim 14 wherein the maximum average grain size has an ASTM grain number of 9.

### Claim 17 (depends on 16)

The method of claim 16 wherein the cathode plate is made of Grade 2 titanium.

### Claim 18 (depends on 12)

The method of claim 12 wherein the cathode plate is made of Grade 5 titanium.