Caltech cells pictures - CNC-JLab machining (Al-7075), June 05, 2003

100.jpg Cell #17, after annealing and thinning, exit window nipple is 8 mm diameter and between 2.9 and 3.2 mils thick. Thickness measured with a Hall probe. The numbers quoted for thickness are coming from the fact that the Hall probe can use different diameter balls, yielding different thicknesses. The bigger the diameter of the ball the more precise is the thickness determination. For machining purposes the cell has been filled with UV glue to about 3/8 in, and the dome has been profiled 360 deg by the CNC. The glue was removed with acetone after machining.

101.jpg Cell #17, inside view.

102.jpg Cell #17, and cell #12 (the first one tried by the CNC and failed), comparison. The piece ofscrap metal on the exit window of #12 is the actual window that was ripped off by the machine.

103.jpg Cell #17, cell #12 and cell #15 (Cu plated).

104.jpg Same three cells, domes compared. The annealed cell has a more pronounced dome.

105.jpg Cell #15, view of the Cu ring.

106.jpg Cell #17, right after the pressure and leak test. The cell was connected to a He bottle and put inside a chamber that was evacuated, the vacuum chamber was in contact with a He leak detector at all times during the pressure test. The cell resisted to 85 psid, there was no significant leak up to 80 psid.

107.jpg Cell #17, side view of the dome and cell after the pressure test.

Caltech cells pictures - CNC-JLab machining (Al-7075) and local machinist (Al-6061), July 16, 2003

200.jpg Cell #15 seemed fine after machining with the CNC, the exit window was measured to be 3 mils in the middle and 2.4 on the edges (a subsequent measurement with a micrometer of the edges of the exit window nipple found it to be 1.7 mils - measurement made by the JLab - target group). The cell burted under pressure, He leaks started appearing at 40 psid, and the cell blew at 65 psid.

300.jpg Cell #2 Al-6061, 7 mils thickness all over except for the 8 mm nipple on the exit window. Passed the pressure and leak test at 70 psid, no wrinkles, but has a "scratch" from doming on a die (it passed the tests with the scratch on it).

301.jpg Cell #3 Al-6061, 7 mils thickness all over except for the 8 mm nipple on the exit window. Passed the pressure and leak test at 70 psid, developed wrinkles after the pressure test.

The two cells that came back from Cu plating, August 8, 2003

400.jpg Cell #17 Al-7075, after two attempts to Cu plate the soldering collar. It doesn't look very smooth on the side, but the exit window is fine. This was supposed to be the primary candidate for cell replacement.

401.jpg Cell #17 Al-7075, at 20 psig, sitting in air. It looks like most of the deformations are smoothed out by the pressure.

402.jpg The fixtures were leak tight in air to snoopping, so we went for the pressure and leak test. With the cell at 20 psid, the leak rate stayed on the scale of 10^-3 mbar.l/s and froze there, suspecting other leaks, besides the fixtures, we pulled the cell out and found a big leak on the side of the cell (that's snoop in the picture). Cell #17 is unrecoverable. The leak is coming through a pin hole most probably made by chemicals used in Cu plating.

403.jpg Cell #17 Al-7075, close-up of the pin-hole area. Cell J2, Al-6061 passed both the pressure test and the leak test at 70 psid with no problems, and it just became the first option for a cell replacement of the existing cell.

The inside of the G0 target manifold, August 8, 2003

500.jpg The windsock. Looks clean and straight.

501.jpg The windsock. View from above.

502.jpg The manifold with the existing Al-6061 cell on it.

503.jpg The manifold, another shot, same cell.

504.jpg The manifold, another shot, same cell.