Radiation source

Claim 3

A method as defined in claim 1 in which the lower electrode has a substantially planar upper surface.

Claim 4

A method as defined in claim 1 in which the lower electrode has a dished upper surface.

Claim 5

A method as defined in claim 1, claim 2 or claim 22 in which said electrodes are mounted within a cylinder that is positioned in said chamber, at least part of said cylinder being transparent to the radiation produced by the powder when said chamber and said cylinder are evacuated to a pressure which is 10 -5 Torr or lower and a voltage difference is applied across said electrodes to disperse at least some of the powder supported on the lower electrode into the space between said electrodes.

Claim 6

A method as defined in claim 1 in which said chamber is a glass container having an open top and a glass base, said upper electrode comprises a metal plate which closes the top of said container, and said lower electrode is a metal plate adjacent to and covering the base of said container.

Claim 9

A method as defined in claim 1 or claim 6, in which said apparatus includes a phosphor which is positioned for irradiation by the X-radiation produced within said chamber.

Claim 10

A method as defined in claim 1 or claim 6 in which a phosphor is included within said chamber for irradiation by the X-radiation produced therein.

Claim 11

A method as defined in claim 1 or 6 in which said powder includes particles of at least one cathodoluminescent phosphor.

Claim 12

A method as defined in claim 1 or 6 in which said means for permitting the transmission of radiation comprises at least one radiation window in said chamber.

Claim 13

A method as defined in claim 1 or 6 in which said upper electrode is a cathode, including the step of heating the cathode to augment field emission of electrons therefrom.

Claim 14

A method as defined in claim 1 or 6 including the step of controlling the output of said X-radiation by varying the potential difference applied to said electrodes.

Claim 15

An X-radiation source comprising: (a) at least two electrodes mounted in an evacuable chamber with one of the electrodes positioned above the other electrode; (b) means to evacuate said chamber; (c) means to apply a high voltage difference to said electrodes; (d) a quantity of a powder of at least one conducting or semi-conducting material supported on the lower of said electrodes when the electrodes have a potential difference that is less than a value of potential difference which produces a minimum dispersing field for said powder; (e) a means permitting transmission of radiation from a region between the electrodes to outside of said chamber; and (f) a phosphor positioned for irradiation by the X-radiation which is produced by the source when the chamber is evacuated to a pressure of 10 -5 Torr or lower and a voltage difference which has a value in excess of the value required to establish the minimum dispersing field for the powder is applied across said electrodes.

Claim 16

An X-radiation source comprising: (a) at least two electrodes mounted in an evacuable chamber with one of the electrodes positioned above the other electrode; (b) means to evacuate said chamber; (c) means to apply a high voltage difference to said electrodes; (d) a quantity of a powder of at least one conducting or semi-conducting material supported on the lower of said electrodes when the electrodes have a potential difference that is less than a value of potential difference which produces a minimum dispersing field for said powder; (e) a means permitting transmission of radiation from a region between the electrodes to outside of said chamber; and (f) a phosphor positioned for irradiation by the X-radiation which is produced by the source when the chamber is evacuated to a pressure of 10 -5 Torr or lower and a voltage difference which has a value in excess of the value required to establish the minimum dispersing field for the powder is applied across said electrodes.

Claim 17

A radiation source as defined in claim 13 in which said phosphor is located within said chamber.

Claim 18

A radiation source, as defined in claim 13 in which said phosphor comprises particles of at least one cathodoluminescent phosphor included within said powder.

Claim 19

A radiation source as defined in claim 13 in which said means for permitting the transmission of radiation comprises at least one radiation window in said chamber.

Claim 20

A radiation source as defined in claim 13 in which said chamber is a cylindrical chamber having a substantially vertical axis and said at least one radiation window is an elongate, substantially horizontal window which extends around said cylindrical chamber.

Claim 21

A radiation source as defined in claim 13 wherein said chamber comprises a ceramic or glass cylinder having a vertical axis and being closed at each end by metal electrodes which are a vacuum-tight seal with the ends of said cylinder, and a single radiation window is formed in one of said metal electrodes.

Claim 22

A radiation source as defined in claim 13 in which the upper of said electrodes is a cathode, including means to heat said cathode to augment field emission of electrons therefrom.

Claim 23

A radiation source as defined in claim 13 including a high voltage DC supply connected across said electrodes.

Claim 24

A radiation source as defined in claim 20 including means to apply an AC ripple voltage to said high voltage DC supply.

Claim 25

A radiation source as defined in claim 13 including an auxilliary electrode within said chamber.

Claim 26

An X-radiation source comprising: (a) a vertically mounted cylinder of insulating material, said cylinder being closed at its upper and lower ends by respective electrically conductive metal closures and being divided into an upper compartment and lower compartment by a thin metallic sheet which is supported on a metal grid, mesh or perforated plate; outlet means in the lower compartment being connected to a vacuum pump which maintains the lower compartment at a pressure of 10 -5 Torr or lower; fluid inlet and fluid outlet means being provided in the upper compartment to enable fluid to pass therethrough; (b) a terminal connected to said thin metallic sheet; (c) means for applying a high voltage difference between said terminal and the lower one of said metal closures; and (d) a quantity of powder of a conducting or semi-conducting material within said lower compartment on the lower of said metal closures; at least part of said powder being dispersed within said lower compartment by application across said terminal and said lower metal closure of a voltage difference which is sufficient to produce at least a minimum dispersing field for the powder; X-radiation thus being generated within said lower compartment and being transmitted into said upper compartment through gaps in said grid, mesh or perforated plate and through said thin metallic sheet.

Claim 27

An X-radiation source comprising: (a) a vertically mounted cylinder of insulating material, said cylinder being closed at its upper and lower ends by respective electrically conductive metal closures and being divided into an upper compartment and lower compartment by a thin metallic sheet which is supported on a metal grid, mesh or perforated plate; outlet means in the lower compartment being connected to a vacuum pump which maintains the lower compartment at a pressure of 10 -5 Torr or lower; fluid inlet and fluid outlet means being provided in the upper compartment to enable fluid to pass therethrough; (b) a terminal connected to said thin metallic sheet; (c) means for applying a high voltage difference between said terminal and the lower one of said metal closures; and (d) a quantity of powder of a conducting or semi-conducting material within said lower compartment on the lower of said metal closures; at least part of said powder being dispersed within said lower compartment by application across said terminal and said lower metal closure of a voltage difference which is sufficient to produce at least a minimum dispersing field for the powder; X-radiation thus being generated within said lower compartment and being transmitted into said upper compartment through gaps in said grid, mesh or perforated plate and through said thin metallic sheet.

Claim 28

An X-radiation source as defined in claim 23 including a quantity of a second powder of a conducting or semiconducting material within said upper compartment on said thin metallic sheet; said fluid inlet means being closed and said fluid outlet means being connected to a vacuum pump which maintains the upper compartment at a pressure of 10 -5 Torr or lower; a second voltage difference being applied across said terminal and the upper metal closure to cause said second powder to be dispersed within said upper compartment; said second powder being thus irradiated by the X-radiation generated in the lower compartment and passing through the gaps in said grid, mesh or perforated plate and through said thin metallic sheet.

Claim 29

A radiation source as defined in claim 23 or claim 24 including a radiation detector in said upper compartment.