AW: [RASMB] lamp intensity drop

[Claus Urbanke]

Hi Dror,

this seems to be a general problem with the XL-A. We had it persistent for
years and the technicians could not fix it.

We usually had to clean the lamp's surface by rubbing it with toothpaste and
a tissue after every second or third run. This brought the intensity back to
almost normal. Most toothpastes contain some mineral clay to polish your
teeth's surface and you use this part of the toothpaste to gently polish
your lamp.

However, two years ago we made an interesting observation: After cleaning
the lamp we could not get vacuum any more because the O-ring of the lamp
housing (the one that is pressed onto the surface of the lamp itself) had
become too thin. After replacing this O-ring with another one we "stole"
from our mechanics workshop the problem with brownish deposits on the lamp
was reduced dramatically. Now we only clean our lamp after every 5th to 10th
run and sometimes do not see any deposit. Our present theory is that some
material from the O-ring evaporated and got deposited on the lamp surface by
some photochemical. The whole process took years to eventually thin out the
O-ring.

Bad news about this is that I do not know what material the new O-ring is
made off. I suppose it is Viton but since it came from a large collection of
different O-rings on the shelf of our workshop I am not sure.  

Maybe this can be of help to you


Claus




Prof. Dr. Claus Urbanke
Medizinische Hochschule Hannover
Labor für Strukturanalyse OE 8830
Tel.: (49) 511 532 9372
Fax: (49) 511 532 5966
E-mail: Urbanke.Claus at mh-hannover.de