US4241592A — Cryostat for borehole sonde employing semiconduct…

Claim 1

Independent Claim 108 words

A borehole logging tool, comprising: an elongated logging tool housing sized for passage through a borehole; a cryostat located within the housing, said cryostat including means defining first and second chambers, said first chamber comprising a generally cylindrical cryogen chamber and forming a reservoir for a cryogenic material and said second chamber surrounding said first chamber and comprising a vacuum thermal insulation chamber; a semiconductor radiation detector located within said second chamber in thermal contact with said first chamber; and an active vacuum pump means mounted within said housing and coupled to said second chamber for continuously maintaining a vacuum therein over the holding time of said cryostat.

Claim 2

Dependent Claim 108 words

A borehole logging tool, comprising: an elongated logging tool housing sized for passage through a borehole; a cryostat located within the housing, said cryostat including means defining first and second chambers, said first chamber comprising a generally cylindrical cryogen chamber and forming a reservoir for a cryogenic material and said second chamber surrounding said first chamber and comprising a vacuum thermal insulation chamber; a semiconductor radiation detector located within said second chamber in thermal contact with said first chamber; and an active vacuum pump means mounted within said housing and coupled to said second chamber for continuously maintaining a vacuum therein over the holding time of said cryostat.

Claim 3

Dependent Claim 15 words

The tool of claim 1 wherein said active vacuum pump means comprises an ion pump.

Claim 4

Dependent Claim 23 words

The tool of claim 1 further comprising thermal radiation shield means located within said second chamber in surrounding relation to said first chamber.

Claim 5

Dependent Claim 70 words

The tool of claim 3 wherein said radiation shield means comprises: at least one generally cylindrical member having thermally reflective surfaces, said cylindrical member being telescoped over said first chamber and being of an axial length at least as great as that of said first chamber; and means supporting said cylindrical member within said second chamber in substantially thermally-conductive isolation from the facing walls of said first and second chambers.

Claim 6

Dependent Claim 13 words

The tool of claim 1 wherein said cryogenic material comprises a melting-solid cryogen.

Claim 7

Dependent Claim 96 words

The tool of claim 5 further comprising: a fill tube extending into said first chamber from the upper end thereof for introducing the cryogenic material into said first chamber as a liquid; and a vent tube extending into said first chamber from said upper end thereof for venting gas from said first chamber during the introduction of said cryogenic material, said vent tube extending into said first chamber a greater distance than said fill tube and defining between its inner end and said upper end of the first chamber an expansion volume for said cryogenic material.

Claim 8

Dependent Claim 113 words

The tool of claim 5 further comprising: means accessible from outside said cryostat when said tool is withdrawn from a borehole for introducing therein a freezing agent for freezing said cryogen, said means including a tubular member of thermally conductive material extending axially through an end wall of said cryostat and said first and second chambers; and a plurality of thermally conductive fins located within said first chamber in thermal contact with said tubular member and said cryogenic material, said fins being radially spaced about the circumference of said tubular member and extending lengthwise of said first chamber over at least that portion of the chamber to be occupied by the cryogenic material.

Claim 9

Dependent Claim 21 words

The tool of claim 1 further comprising thermal conductor means within said first chamber for promoting temperature uniformity within said chamber.

Claim 10

Dependent Claim 37 words

The tool of claim 8 wherein said thermal conductor means comprises a plurality of thermally conductive fins extending lengthwise of said first chamber over at least that portion of said first chamber occupied by the cryogenic material.

Claim 11

Dependent Claim 38 words

The tool of claim 1 wherein said active pump means is operable to maintain the pressure within said second chamber at 10 -4 Torr. or less over at least a portion of the holding time of said cryostat.

Claim 12

Dependent Claim 18 words

The tool of claim 1 wherein the outer diameter of said housing is not more than 3 inches.

Claim 13

Dependent Claim 21 words

The tool of claim 1 wherein all seals established between the interior and exterior of said second chamber comprise metal-to-metal seals.

Claim 14

Dependent Claim 19 words

The tool of claim 1 wherein said active pump means is mounted externally of said first and second chambers.

Claim 15

Dependent Claim 104 words

The tool of claim 13 further comprising: means accessible from outside said cryostat when said tool is withdrawn from a borehole for introducing therein a freezing agent for freezing said cryogen, said means including a tubular member of thermally conductive material extending axially through an end wall of said cryostat and said first and second chambers; and means for mounting said active pump means axially adjacent said end wall of the cryostat such that said pump means may be displaced to permit said introduction of the freezing agent into the cryostat without disconnecting the vacuum coupling between said pump means and said second chamber.

Claim 16

Dependent Claim 45 words

The tool of claim 13 further comprising: a second cryostat located within said housing and externally of said first cryostat, said second cryostat containing a cryogenic material; and means establishing thermal contact between the cryogenic material in said second cryostat and said active pump means.

Claim 17

Dependent Claim 35 words

The tool of claim 1 wherein said active pump means is mounted within said second chamber; and wherein said tool further comprises means establishing thermal contact between said active pump means and said cryogenic material.

Claim 18

Dependent Claim 32 words

The tool of claim 1 further comprising valve means in said cryostat for permitting attachment thereto of a second vacuum pump for establishing a desired vacuum pressure level within said second chamber.

Claim 19

Dependent Claim 78 words

A borehole logging tool comprising: an elongated logging tool housing sized for passage through a borehole; a cryogen chamber located within the housing; a vacuum thermal insulation chamber surrounding the cryogen chamber; a semiconductor radiation detector located within said vacuum chamber in thermal contact with said cryogen chamber; and an active vacuum pump means mounted within said housing and coupled to the vacuum chamber for continuously maintaining a vacuum therein over the holding time of said cryogen chamber.

Claim 20

Dependent Claim 78 words

A borehole logging tool comprising: an elongated logging tool housing sized for passage through a borehole; a cryogen chamber located within the housing; a vacuum thermal insulation chamber surrounding the cryogen chamber; a semiconductor radiation detector located within said vacuum chamber in thermal contact with said cryogen chamber; and an active vacuum pump means mounted within said housing and coupled to the vacuum chamber for continuously maintaining a vacuum therein over the holding time of said cryogen chamber.

Claim 21

Dependent Claim 100 words

A cryostat for cooling a semiconductor radiation detector in a logging tool in a restricted space-high temperature environment, comprising: an elongated cryostat housing having a comparatively small transverse cross-sectional size; a cryogen chamber within the housing forming a reservoir for a cryogenic material; a vacuum thermal insulation chamber within the housing surrounding the cryogen chamber; a semiconductor radiation detector located within the vacuum chamber in thermal contact with the cryogen chamber; and an active vacuum pump means mounted within said housing and coupled to the vacuum chamber for continuously maintaining a vacuum therein over the holding time of said cryostat.

Claim 22

Dependent Claim 100 words

A cryostat for cooling a semiconductor radiation detector in a logging tool in a restricted space-high temperature environment, comprising: an elongated cryostat housing having a comparatively small transverse cross-sectional size; a cryogen chamber within the housing forming a reservoir for a cryogenic material; a vacuum thermal insulation chamber within the housing surrounding the cryogen chamber; a semiconductor radiation detector located within the vacuum chamber in thermal contact with the cryogen chamber; and an active vacuum pump means mounted within said housing and coupled to the vacuum chamber for continuously maintaining a vacuum therein over the holding time of said cryostat.

Claim 23

Dependent Claim 15 words

The cryostat of claim 19 wherein said active vacuum pump means comprises an ion pump.

Claim 24

Dependent Claim 22 words

The cryostat of claim 19 further comprising thermal radiation shield means within the vacuum chamber in surrounding relation to the cryogen chamber.

Claim 25

Dependent Claim 22 words

The cryostat of claim 19 further comprising thermal conductor means within the cryogen chamber for promoting temperature uniformity within the cryogen chamber.

Claim 26

Dependent Claim 16 words

The cryostat of claim 19 wherein the active pump means is mounted within the vacuum chamber.

Claim 27

Dependent Claim 111 words

A cryostat, comprising: means defining a cryogen chamber forming a reservoir for a cryogenic material; means defining a vacuum thermal insulation chamber surrounding the cryogen chamber; a fill tube extending into the cryogen chamber from one end thereof for introducing the cryogenic material into said chamber; and a vent tube extending into the cryogen chamber from said one end thereof for venting gas from the cryogen chamber during the introduction therein of the cryogenic material, said vent tube extending into the cryogen chamber a greater distance than the fill tube and defining between its inner end and said one end of the cryogen chamber an expansion volume for the cryogenic material.

Claim 28

Dependent Claim 111 words

A cryostat, comprising: means defining a cryogen chamber forming a reservoir for a cryogenic material; means defining a vacuum thermal insulation chamber surrounding the cryogen chamber; a fill tube extending into the cryogen chamber from one end thereof for introducing the cryogenic material into said chamber; and a vent tube extending into the cryogen chamber from said one end thereof for venting gas from the cryogen chamber during the introduction therein of the cryogenic material, said vent tube extending into the cryogen chamber a greater distance than the fill tube and defining between its inner end and said one end of the cryogen chamber an expansion volume for the cryogenic material.

Claim 29

Dependent Claim 44 words

The cryostat of claim 24, further comprising a plurality of thermally conductive fins within the cryogen chamber and extending lengthwise thereof over at least that portion of said chamber occupied by the cryogenic material, whereby said fins promote temperature uniformity within the cryogen chamber.

Claim 30

Dependent Claim 68 words

The cryostat of claim 25 further comprising means for introducing an agent in said cryogen chamber for cooling the cryogenic material, said means including a tubular member of thermally conductive material extending axially through said one end of the cryogen chamber and wherein said plurality of thermally conductive fins are in thermal contact with said tubular member and are radially spaced about the circumference of said tubular member.

Claim 31

Dependent Claim 37 words

A borehole logging tool according to claim 1 or 18, wherein said cryostat is arranged between said detector and said pump within said elongated housing for protecting said detector from outgassing and other emissions from said pump.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1983-12-30	1984-06-30	1984-12-30	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1987-12-30	1988-06-30	1988-12-30	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1991-12-30	1992-06-30	1992-12-30	$7700.00	Window Closed / Lapsed

Cryostat for borehole sonde employing semiconductor detector

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag