[time-nuts] So what’s inside that Cs Beam Tube anyway?

[Clint Jay]

There's a sectioned Cs tube at the science museum in London,  sadly I can't
see the pics you link to but I'd be interested to see if they're the same
as that exhibit (I think I have a picture somewhere)

On 31 Oct 2016 20:54, "Skip Withrow" <skip.withrow at gmail.com> wrote:

> Hello Time-Nuts,
>
>
>
> I recently acquired a stock of dead cesium beam tubes, and my curiosity got
> the best of me, so I have cut one open.  After watching lots of YouTube
> video of burning and exploding cesium I was a little leery at first. The
> first step was to make a very small hole just to let a small amount of air
> in, no flames or heat so I let it sit for a while for any reactions with
> air to take their course.  Next I proceeded to cut off the ends, and after
> that the bottom of the unit, finally I trimmed the top off as far as I
> could.  Pictures are linked below for your enjoyment.  I have attached two
> of the before and after at low resolution.
>
>
>
> 1. http://www.rdrelectronics.com/skip/CS-tube/cstube1.jpg
>
>
>
> This is the before picture of a tube (not the actual one opened).  It is HP
> part number 05061-6077.  The band around the center of the tube is a mu
> metal shield that is removed by removing the screws along the seam.
> Unfortunately
> 11 of the 14 tubes that I received had the cables cut as shown (ouch!).
>
>
>
> 2. http://www.rdrelectronics.com/skip/CS-tube/cstube2.jpg
>
>
>
> This is a shot of the deconstructed tube.  The cesium oven is on the left,
> the microwave cavity is in the center (under a metal cover), and the
> detector is on the right.
>
>
>
> 3. http://www.rdrelectronics.com/skip/CS-tube/cstube3.jpg
>
>
>
> This is the oven end of the tube.  The oven (with the cesium) is the copper
> vessel.  The ion trap assembly is at the top (with magnet).  The first beam
> magnet is between the oven and the microwave cavity.  One thing that I can
> say is that HP brought the art of spot welding to a new level.  Note the
> stainless steel strips welded over the screw heads (and lots of other
> things).
>
>
>
> 4. http://www.rdrelectronics.com/skip/CS-tube/cstube4.jpg
>
>
>
> This is the detector end of the tube.  I believe the hot wire ionizer is
> the broken metal strip.  The electron multiplier/detector is in the metal
> box above it.  The second beam magnet sits between the microwave cavity and
> the electronics at this end of the tube.  I don’t think I broke the
> filament, this was probably the failure mode of this tube.  Also note that
> all the wiring insulation is ceramic tubing, since insulation that out
> gasses in vacuum is a no-no.
>
>
>
> 5. http://www.rdrelectronics.com/skip/CS-tube/cstube5.jpg
>
>
>
> This is the bottom view of the tube for completeness.  I have not yet
> removed the cover that is over the microwave cavity (and has the C-field
> coil around it).
>
>
>
> 6. http://www.rdrelectronics.com/skip/CS-tube/cstube6.jpg
>
>
>
> This is the top of the tube with the potting compound removed.  I was
> surprised to find a couple of embedded resistors.  I guess the good news is
> that it would be easy enough to remove the potting and solder on new wires
> if deemed useful.
>
>
>
> 7. http://www.rdrelectronics.com/skip/CS-tube/cstube7.jpg
>
>
>
> This is just a close-up of the broken hot wire ionizer (and all the spot
> welds).
>
>
>
> 8. http://www.rdrelectronics.com/skip/CS-tube/cstube8.jpg
>
>
>
> This is a close-up of the ion trap where the +3500V connects.  I’m not a
> physics expert, but didn’t think about a magnet being involved.  I don’t
> think any of the drawings that I have seen have ever mentioned it.
>
>
>
> So, enjoy.  I will most likely be throwing the rest of the tubes up on ebay
> at some point.  If there is strong interest in having them cut open first
> please let me know.  I intend to cut up some wood to make an appropriate
> stand and add this one to my tube collection.
>
>
>
> Sorry for the long post, but I hope you found it informative.
>
> Regards,
>
> Skip Withrow
>
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