The inverted gun is described in M. Breidenbach et al., "An inverted-geometry,
high voltage polarized electron gun with UHV load lock," Nucl. Instrum. and Meth.
A350, 1 (1994). Since about that time it has been stored, under vacuum, in the
High Voltage Test Facility (B008) at SLAC.
The gun uses 3 ceramic insulators to support the cathode
assembly. These insulators are 12.00-inches long (overall 12.75-inches if
0.375-inch ceramic extensions are included) with OD/ID of ~1.75/1.00-inches. All
4 of the spare insulators have SST welding eyelets brazed to each end.
Insulators nos. 1-3 are the original style (Style I, SA-243-006-55), one of which suffered a HV
punch-through. Each of these insulators also has a SST cup welded to one eyelet. Insulator 4
(no SST cup) has 5 metalized bands on the outside plus a Cr & Ti oxide coating
inside and out (except for the ceramic extensions). This is Style III,
SA-243-006057. To remove an insulators after installation, the weld at the
eyelet had to be ground off.
The yellowish photos were taken with only the room fluorescent lighting. The
whiter photos were taken with a flash.
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2. Insulator 1, style I, unused. |
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3. Insulator 1, style I, unused. SST cup. |
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4. Insulator 1, style I, unused. Note smooth edge of eyelet. |
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5. Insulator 1, style I, unused. View down bore to show ceramic extension. |
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6. Insulator 1, style I, unused. Another view down bore. |
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7. Insulator 2, style I, used. |
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8. Insulator 2, style I, used. Note rough edge of eyelet. |
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9. Insulator 2, style I, used. |
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10. Insulator 2, style I, used. |
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11. Insulator 3, style I, used. Note damage. |
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12. Insulator 3, style I, used. Damaged area optically enlarged. |
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13. Insulator 3, style I, used. Attempt at additional optical enlargement of damaged area. |
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14. Insulator 3, style I, used. Another view of damaged area. |
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15. Insulator 3, style I, used. This end of ceramic extension is taped over. |
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16. Insulator 3, style I, used. |
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17. Insulator 4, style III, unused. Note there is no SST cup. |
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18. Insulator 4, style III, unused. Note the ceramic extension is not coated. |
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19. Insulator 4, style III, unused. |
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20. Insulator 4, style III, unused. |
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21. Insulator 4, style III, unused. |
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25. Parts for one segmented insulator. |
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26. Three well-preserved coated insulators. |
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