fluorescent lamp with a (cylindrical) tube with variable length

[ghasem_008]

hi.
is there any fluorescent lamp with a (cylindrical) tube with variable length?
for a specific project,I have to control length of a fluorescent lamp.
is there anyone who can give me a suggestion?

 

[FvM]

What do you mean with variable length?

Fluorescent lamps can be made in arbitrary lenghts and shapes. You need a glassblower to make it.

 

[ghasem_008]

please see the following picture:

in this picture,length "L" is variable and I want to change it when I need to different "L".
in fact my fluorescent lamp is fixed (and attached to AC voltage via electrodes and has step by step tube in "L" section.
can I produce it?

 

[ghasem_008]

Is there anyone who help me?

 

[FvM]

I fear the question isn't clear. Are you asking for a flexible glass tube (which doesn't exist, unfortunately) or how to order glas tubes of different length and make fluorescent lamps?

The internal space of a fluorescent is evacuated and filled with low pressure noble gas and mercury vapour, about 0.3% of atmospheric pressure, so any kind of movable seal isn't feasible.

 

[chuckey]

You can get vacuum tight bellows, like a corrugated hose. They have a total movement of about 20mm. We tuned klystrons by displacing one end of the bellows which then moved an internal tuner in or out. The vacuum inside the klystron was at a very low presssure. They were about 70mm external diameter. Big but, you need some serious high vacuum technology to install then in series with a glass tube. Ours were mounted on the copper plates (part of the tuning cavities).
Frank

 

[schmitt trigger]

Why do you need a variable length tube for?

 

[televisodes81]

why do you melong