CO2 Power Supply Schematic Help

[Sigurthr]

Note that when running at the spec'd DC current on AC instead, only 70% power will be attained.

I'm with the others on a ruptured bore or broken suppression spiral.

 

[ultimatekaiser]

Well the tube is designed for DC... I don't get why people want to run them with AC. It's rather hard on the tube internally, and you lose power.

But yeah if you have too strong of an ignition pulse, or too long, you can actually punch a tiny micro-hole through the bore and out into the reservoir. This is a rare problem with HeNes I've seen doing the same thing. Then the discharge doesn't take place inside the bore any longer, as the reservoir is now the path of least resistance.

 

[Sigurthr]

Well the tube is designed for DC... I don't get why people want to run them with AC. It's rather hard on the tube internally, and you lose power.

Inexpensive and easily acquirable HVAC 50/60Hz transformers.

But yeah if you have too strong of an ignition pulse, or too long, you can actually punch a tiny micro-hole through the bore and out into the reservoir. This is a rare problem with HeNes I've seen doing the same thing. Then the discharge doesn't take place inside the bore any longer, as the reservoir is now the path of least resistance.

Btw, there is an unofficial "fix" for this. You RF drive the tube balls out. I had an EOL HeNe that the hard-start nature resulted in the starter continuously running, thus blowing a hole in the bore. 150Watts of RF made the tube Lase again for several years.

 

[ultimatekaiser]

Inexpensive and easily acquirable HVAC 50/60Hz transformers.

True, but if you're spending hundreds of dollars on the laser tube you might as well at least drive it correctly...

Btw, there is an unofficial "fix" for this. You RF drive the tube balls out. I had an EOL HeNe that the hard-start nature resulted in the starter continuously running, thus blowing a hole in the bore. 150Watts of RF made the tube Lase again for several years.

Well....that's not really a fix...more of a workaround. :tinfoil: but yeah it does work! Though you greatly shorten the tube lifespan by doing that. It destroys the cathode pretty fast.

 

[Sigurthr]

I didn't notice much cathode degradation, at least not visually, but I capacitively coupled the RF to the tube, so I wasn't even using the cathode connection for the bulk of the current, really. But, when the tube is EOL or broken, what do you have to lose, right?

Btw, you might want to edit and split that quote, I missed your reply to the psu comment the first time since it is in the quote attributed to me. I agree, wholeheartedly, btw. It isn't like chinese PSUs are all that expensive anyway.

 

[ultimatekaiser]

I didn't notice much cathode degradation, at least not visually, but I capacitively coupled the RF to the tube, so I wasn't even using the cathode connection for the bulk of the current, really. But, when the tube is EOL or broken, what do you have to lose, right?

Btw, you might want to edit and split that quote, I missed your reply to the psu comment the first time since it is in the quote attributed to me. I agree, wholeheartedly, btw. It isn't like chinese PSUs are all that expensive anyway.

Very true. And yeah I caught that and fixed it while you were typing

 

[upaa27]

Is there a gas or something that you can possibly/logically pump into the outer tube so that it increases resistance there?

For rf excitance how to you go about doing that? Put it in a low powered microwave?

Tell me what you guys need to see in the shots. I didn't find any cracks anywhere but if there is a micro leak like kaiser said...

 

[The Lightning Stalker]

I'm not sure if this has anything to do
with it or not, but I was looking at some
diagrams of Chinese CO2 laser tubes, and
they actually specify a direction of flow
and to run the tube with the water outlet up.

 

[Cyparagon]

We need a shot of where the spiral connects to the bore. Preferably with it running.

 

[upaa27]

We need a shot of where the spiral connects to the bore. Preferably with it running.

Will do asap.

I'm not sure if this has anything to do
with it or not, but I was looking at some
diagrams of Chinese CO2 laser tubes, and
they actually specify a direction of flow
and to run the tube with the water outlet up.

Hmm thanks for the diagram! Of course I am running it he other way I will retube it asap

 

[Sigurthr]

RF excitation isn't easy on a CO2 tube since you've got water cooling as well. I wouldn't microwave it since the water is opaque to 2.4GHz. You'd need to build a specialized driver for it consisting of an oscillator control board, a gate drive board, and a half or full bridge inverter, which then drives a step up air cored transformer, similar to a tesla coil. Coupling is then done by utilizing the anode electrode and an exterior electrode wrapped around the cathode end. A power resistor (or better, an RF cap used as capacitive ballast) can connect the extrinsic electrode to the cathode electrode. Anywhere from 100KHz well up into tens of Mhz would work fine. You'd have to watch for dielectric heating of the envelope and corona production. Both of which probably necessitate an oil shroud for long duration runs.

 

[upaa27]

Sorry for the huge amount of pics. Camera had a hard time taking pictures really close to the tube due to the iPhone using capacitance to register clicks.

I took pictures of the most abnormal and problematic looking things going on in there

 

[upaa27]

Tube is a dud now isn't it?

 

[Cyparagon]

It's clearly corona/glow discharge, since there's no electrode on the mirrors. I still think there isn't enough power.

 

[Sigurthr]

Here's the odd thing:

In this image http://i.imgur.com/T02fdtl.jpg You can see a plasma stream going from the electrode TO the mirror. This suggests significant current is flowing from the electrode to the mirror and to the water cooling supply. This is BAD. Mirrors aren't designed to carry any current or come in contact with the plasma stream.

You need to flush the tube with clean water and run it on deionized water or even flush with alcohol and then run on mineral oil. If you wish to salvage this tube at all you need to prevent plasma flow to the mirror.

I don't know if the power supply is just inadequate, or if this tube cannot be run on AC at all, as this is highly atypical behavior, but until the mirror being in circuit situation is rectified it doesn't really matter. You're going to destroy your mirrors at this rate. (Also, that point of the wire connecting the electrode is not meant to be in contact with plasma either, and it WILL wear out too.)

 

[upaa27]

Here's the odd thing:

In this image http://i.imgur.com/T02fdtl.jpg You can see a plasma stream going from the electrode TO the mirror. This suggests significant current is flowing from the electrode to the mirror and to the water cooling supply. This is BAD. Mirrors aren't designed to carry any current or come in contact with the plasma stream.

You need to flush the tube with clean water and run it on deionized water or even flush with alcohol and then run on mineral oil. If you wish to salvage this tube at all you need to prevent plasma flow to the mirror.

I don't know if the power supply is just inadequate, or if this tube cannot be run on AC at all, as this is highly atypical behavior, but until the mirror being in circuit situation is rectified it doesn't really matter. You're going to destroy your mirrors at this rate. (Also, that point of the wire connecting the electrode is not meant to be in contact with plasma either, and it WILL wear out too.)

Damn. So I need to flush the tube and run it on DI water or mineral oil to make in not jump to the mirror? So this will basically just make the mirrors salvageable but the tube is done? Should I just smash the tube for the mirrors before any further damage is done?

Can I rectify the nst while putting DI water through to fix the problem or is the tube dead?