[Sneap] tungsten mesh sought for gridded Einzel

[Howard Evans]

Albert,

You probably want a photo chemically etched tungsten mesh instead of an electroformed mesh.

We use a molybdenum, gridded, tube-lens at the low-energy column entrance of our Tandetron General IonX tandem accelerator to focus negative ions onto the aperture of the stripper canal. It is a disk about four inches in diameter, about 0.006 inches thick, with a fine-pitched array of hexagonal holes offering 90% or better transmission. The hexagonal holes were photo chemically etched by Buckbee Mears of St. Louis into a sheet about five inches on a side with a quarter-inch border all around. We cut a disk from this stock to make the tube lens.

Unfortunately, Buckbee Mears is no more. I think they used to make shadow masks for color television CRTs, but the United States no longer manufactures in that market. I went looking for a replacement manufacturer and found a small company in New England, Tech-Etch, Inc., 45 Aldrin Road, Plymouth, MA 02360, TEL 508-747-0300 * FAX 508-746-9639 (http://www.tech-etch.com).      
They also have offices here: Tech-Etch Litchfield, 1 Precision Drive, Litchfield, MN 55355, TEL 320-593-0240 * FAX 320-593-0241.

I spoke with Steven Sylvia, Business Manager, Custom Precision Parts, tel: 1-508-747-0300 x3059, fax: 1-508-746-9639 about thirty-two months ago (Mar 2005) and he assured me they could make the molybdenum grid if I would send him a sample from which they could generate artwork.

Give Steve a call to see if he can help you.

Howard

******************************************************
Howard B. Evans, Jr.
Engineer, Materials Laboratory
UES, Inc.
4401 Dayton-Xenia Road
Dayton OH  45432-1894

937-426-6900 ext. 116 (office and voice mail) or ext. 121 (lab)
937-426-5718 fax

hevans at ues.com e-mail
http://www.ues.com web site

"Things should be explained as simple as
possible, but not simpler." -- A. Einstein

*******************************************************



-----Original Message-----
From: sneap-bounces at tunl.duke.edu [mailto:sneap-bounces at tunl.duke.edu]On
Behalf Of Albert Zondervan
Sent: Wednesday, October 31, 2007 6:58 PM
To: Sneap at tunl.duke.edu
Subject: [Sneap] tungsten mesh sought for gridded einzel


Hi SNEAPers

>> Where do I source electroformed tungsten mesh ?
I am servicing a gridded Einzel lens and its tungsten, 1mm pitch, grid has 
deteriorated somewhat. I think the existing grid was custom-made a long 
time ago by an american company, via electroforming. Obviously, 
light-optical transmission should be >=90%. Minimum required area 100x100 
mm2.

Your suggestions and comments most welcome. If you have some spare on 
hand, I'll be happy to pay costs.

cheers
Albert
-- 
Albert Zondervan
National Isotope Centre
GNS Science                              A.Zondervan at gns.cri.nz
PO Box 31-312, Lower Hutt                ph: +64 4 570-4617
New Zealand                              fx: +64 4 570-4657
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