Hi Atilla,

Usually we use linear quartz lamps T3 series which are produced for power from 500 to 2000 W. A lot of companies produce them; you can find them at www.infraredheaters.com/quartz3.html, for instance. However they are not UV lamps, they work mainly in VIS and IR range. They work fine if you need not just "dry" your chamber and tooling, but also to heat up substrates up to 300C - 350C maximum.

If you need just to desorb water from vacuum surfaces and leave them relatively cold - it would be better to use UV lamps or glow discharge.

Best regards,

Vladimir

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Hi,

Heating will do perfectly well, but the whole point of using UV lamps is to avoid heating the system. UV
of a suitable wavelength actually breaks down the water molecules and releases them from the surface
of the chamber. Wavelengths are around 200nm. For a good overview of the topic, check out this
page and the associated links -



Cheers,

Lindsay

I have an old Veeco vacuum system with a ≈3" diff. pump (air cooled) using 100cc of DC-704 (per factory spec).

I've torn down the entire system, cleaned it (I had to clean and rebuild the DP, as it had been dived to atmosphere hot with octoil or the like in it, and was full of tar / carbon).

The original unit should have had a 375 watt heater in it. The heater on it now is dissipating 428 watts. Interestingly, Duniway and a couple of other places sell only 350 watt heaters as direct replacements for this pump. I don't recall what temp Octoil wants, but I know that different oils require different temperatures. What I don't know is how critical that temperature is.

There is no temperature control, although I could install one at minor expense. As I understand it, too-high heat should not harm pumping action, but FAR too much heat will cause erratic pressure variations as excess condensation interferes with the jets.

So, how important is precise temperature control of the boiler? Should I pick up a temperature controller (using the present too-high wattage heater and a thermocouple) or should I replace the heater with a 375 watt unit, or a 350 watt unit, or should I just not worry about it?

Attila,

Are you quite certain you don't mean "IR" instead of "UV"?
It sounds like what you want is heat.

Your pumping system removes teh water vapor from the chamber volume, the usual water problem after that is a water monolayer sticking to the walls. this is why it's important, once you've cleaned the thing and pumped it down really well, that you leave the chamber closed and under vacuum at all times when it is not actively being loaded or unloaded.

As for getting rid of the water monolayer on the walls, you usually need to heat the surfaces to a surprisingly high temperature, usually well over the boiling point of water (after all, it's under vacuum and it's still there). Where I work, we drive water vapor off the surfaces of the laser tubes we build in vacuum ovens running at over 200°C.

Make sure your chamber and its seals can handle such high temperatures. 200°C is pushing it for Viton O-rings. If your chamber is all CF, then no worries.

I can't think why you'd need UV for this purpose.

--- In VacuumX@..., "Attila" <schneyolo@...> wrote:

Hi All,

Does know anybody, what kind of UV lamp should use in a vacuum chamber, for heating. Eliminating the water vapour?

ThX!

Attila
The Hun

Atilla, Hi. Don't know what brand they are, but our surplus tank came with long, thin, quartz heaters. They really heat the tank up fast and are really bright. You can see the electrical connections to them on the bottom in this picture: Other info contained in this forum : and www.fusor.net. Thanks. -bill fain

Hi All,

Does know anybody, what kind of UV lamp should use in a vacuum chamber, for heating. Eliminating the water vapour?

ThX!

Attila
The Hun

Hello Zafar,

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Dear Asad

Where u r supplying these mirrors

Dr.Zafar Iqbal

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To: VacuumX@...
From: asadscientist@...
Date: Fri, 3 Sep 2010 19:59:41 -0700
Subject: Re: [VacuumX] 6" mirror coating

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Dear Asad

I am rebuilding the e-beam evaporation coating facility at National center of Physics Islamabad. will be ready in next six months. keep in touch for your work. Will do the necessary help.

Where are you in Pakistan. What you are professionally

Zafar

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To: VacuumX@...
From: asadscientist@...
Date: Thu, 2 Sep 2010 06:17:05 +0000
Subject: [VacuumX] 6" mirror coating

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What is the price of the coating chamber that is for sale?

Asad

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Drew...

You are one lucky guy!

During one of my rare lucid moments I found 4 of the rotary actuators I mentioned yesterday. These would be very easily modified by the addition of a vane (or flag) to cover the opening of your evap box during the initial heating of the material. I would position the flag in a fail-safe manner i.e. with the opening covered unless the actuator is powered up. I believe these are 24VAC movements but should be fairly easy to figure out.

If you have a variable power supply (XMS?) you could ramp up the voltage until they move then measure the voltage and add a bit for reliability sake. I can't remember if the XMS had 120vac outputs for the switched devices or not but a doorbell transformer (or voltage dropping resistor) might just be the ticket if so.

Not sure about how they would behave in a vacuum re: outgassing, oils etc. They seem to be "dry" but any mechanism is likely to outgass for a while in vacuum.

Already addressed in a box and will be on your way this weekend.

Ken

--- In VacuumX@..., "Aurigema, Andrew N. (KSC-ASRC-474)[ASRC AEROSPACE]" <andrew.n.aurigema@...> wrote:

Hey, do you have another one of them things ??? I want to install a second one so I can run two of them heater baffle boxes at the same time. I got two of them monster transformers in my welder box that I am using as the power supply.

NOPE... Don't have any more of those SCR Controller thingies. Got that one off eBay for a song just to try it out and was impressed with what it could do. If you search eBay , tyou should find several of them on there. Was quite a few available when I got that one a few years back. Just look for a single phase 220Volt unit with 0-10 volt control input. The unit I got was 0-5 volt so I put a voltage divider on the output of the XMS box to make it play nice.

I am thinking that I will have to create a blocker of some kind to catch the initial sputtering from the baffle box as it heats up. You got any idea on that ???? The controller will actuate it on command so control is not a problem.

YEP... I have some rotary solenoids (had?) in a box somewhere. Got them just for that possible reality. I take a look and post them to you if I find them.


Ken

It is easy and tricky at the same time...

1. It works only for transparent in the given light wavelength range film materials.
2. The intensity of reflected or transmitted light varies with film thickness as sinusoid. Light intensity minimums or maximums take place when the film optical thickness nd (n - film material refraction index for the given monitoring wavelength L, mcm, d - physical film thickness, mcm) = kL/4, where k = 1, 2, 3,.... For instance, for TiO2 film with n = 2.3 deposited on glass substrate and monitoring wavelength 600 nm reflected light intensity first maximum will be at film thickness (550/4)/2.3 = 59.8 nm, then minimum at 119.6 nm, then second maximum at 179.4 nm, second minimum at 239.2 nm , and so on. In general, you can select wavelength to obtain required thickness when reflected or transmitted light gets extremum, on practice it is not so easy.

Don't forget, that the film thickness deposited on unmoving monitor sample is not equal to film thickness deposited on rotating parts. Do not forget about film thickness non-uniform distribution over substrate holder. And there are some extra tricks. You need to use correction coefficients obtained for your machine in experiment.

There are a few softwares allowing to calculate optical monitoring, TFCalc, for instance. As a device, it is not very hard to make it yourself, but better to use a professional one. There are not a lot of them on the market from about 10K (simpliest) to 40K (the best).

Regards,

Vladimir

zafar0126 wrote:

Dear ALL

Hoe measure the thin film thickness by refelction and transmitted light using monochoromator.

I need basic information for this methode

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Hi, Everybody!

I bought an old CVC coater a few years ago, intending to fix it up and start coating telescope mirrors. But I got too busy making the mirrors, so this coater project has languished. Now it's time to sell this to somebody that has the time and energy to put her back into working order.

The bell chamber is about 23.5" in diameter, and about 27.5" tall inside. I am including a rebuilt roughing pump, and a rebuilt diffusion pump, neither of which has been used since I bought them. I did run the roughing pump for a minute to make sure it would pull a vacuum. There's also a bunch of stuff like coils, aluminum pieces, SiO, diffusion pump oil, an evaporation boat, a fixture and so forth.

I have a write-up on the system, plus many, many photos on my Web site at . Click on the coater item under the "What's New" area at the top left of the page and have a look. Enjoy yourself, and feel free to make any offer on the system that would work for you. It's gotta go, so if you want a good coater project, this is a great opportunity for you. Thanks!

Gordon Waite
Waite Research

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Hello Alfredo

Mnay Thanks for the efforts

I am having an old chinese (1990) made EB deposition system. I am rebuliding it from scratach. Every thing is alredady fitted in the vacuum chamber. The manuals are avaiable. It was built by China precision Machinery Corporation. now this company does not exist. I hope if stucked in the problem i will contact you. Please keep my name in your directory

Regards

Zafar

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To: VacuumX@...
From: aneves@...
Date: Tue, 24 Aug 2010 16:35:35 +0000
Subject: [VacuumX] Re: E-Gun Evaporator

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