Category Archives: General Optics and Vacuum

General information on repair, maintenance, and operation of both PHI (Physical Electronics) and other manufacturers’ systems and components

11-065 28 Volt supply Check

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The 28 V DC power supply in the PHI 11-065 ion gun control can become weak and cause symptoms such as low emission current. To test the supply, measure the voltage from the red wire to chassis ground. It should be 28 volts to 29 volts DC, with less than 100mV AC ripple. When defective, the DC voltage will be low (about 10 to 16 volts) and there will be high AC ripple (3 to 6 volts).

Measure from the red wire post to the chassis.  CAUTION – refer servicing and testing to qualified personnel.

28-volt-supply-test-point

28-volt-supply-test-point

 

 

If your 11-065 28 volt supply is defective, RBD carries them in stock at all times. Contact us for more information.

Multi channel detector continuity tests

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The multi channel detector (MCD) assembly found on Physical Electronics 5500 through 5800 X-ray photoelectron spectroscopy (XPS) systems comprises two pieces – the channel plate assembly and the connection flange.

If you follow the procedure in the 10-360 spherical capacitive analyzer manual you can replace the channel plates (Chevron type) without too much difficulty. Two things to remember are to use some small Allen wrenches to hold the pins up (that removes the spring tension) and to make sure that the little marks on the channel plates face each other.  This drawing might be helpful – MCD detail

But equally important as installing the channel plates correctly is ensuring that you have good continuity on all of the pins on the connection flange, and that you are making a good electrical contact with the channel plate assembly when you install the flange.

Before you install the connection flange, short out the pins on the connector flange with aluminum foil as shown in the pictures below. Then use an ohmmeter to measure the continuity of each pin to the flange. Each pin should have a resistance of less than 2 ohms. Sometimes the pins can become oxidized and if so the resistance can be high, as high as Meg ohms. If the resistance on one or more pins is high, very carefully use a tweezers and pull up on the wire on the end that is close to the connector. Move it no more than 1/16″ up and down. If you move it up too high, the pin will come off the connector pin and it is very difficult to put those back on. Verify that each pin has good continuity and is all the way down before installing the connection flange.

When you install the connection flange (after first installing the channel plate assembly inside the SCA) measure the capacitance of each pin to the chamber. They should all have the same capacitance, typically about 250 pf. The 4 middle pins are not used so their capacitance will be about 100 pf. If the other 16 pins do not all have the same capacitance, then the some of the spring contacts are not making contact with the channel plate assembly. Try rotating the flange a little bit. You may need to slide the connection flange back a little bit and then reseat it. Just be sure that each pin has the correct capacitance before tightening the connection flange.

Finally, the pins on the connection flange may have been bent slightly during the continuity test. Visually inspect the pins and carefully slide on the MCD preamp to make sure that it will go on without bending any of the pins. Adjust the pins as needed until the MCD preamp can go on easily. The pins on the connection flange are very soft and can bend easily. It is possible to force the MCD preamp down on a bent pin and if so, the pin will usually break when you try to straighten it. So just be aware that this and you will not bend the MCD pins.

 

RBD Instruments provides the MCD channel plates and technical support to help you with the installation.

 

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MCD pins
MCD spring contact pins

PHI 15kV Dual Anode X-ray Source Outgas Procedure

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This is the procedure that I use to ensure proper outgassing and conditioning of the PHI 04-500 and 04-548 15kV Dual Anode X-ray source after installation or bake-out. It is a slight variation from the procedure in the 32-095 out-gas activate procedure.

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Initial Installation

After installing the source, the system must be pumped down and baked out. If you are unable to bake-out the system, you should at a minimum wrap some heat tape around the flange on the source and heat it to 150 degrees C for a period of 8 to 12 hours.

After the bakeout is complete, reconnect the water lines and check for leaks by turning the x-ray source control on for 15 minutes. Sometimes there are small leaks that form a drop or two after 5 minutes. If there are no leaks after 15 minutes you can shut off the x-ray source control and connect the high voltage lead, the Teflon shield and the second cover.

Note: Make sure that the high voltage wire is tight and that the water flow is correct. See the info at the end of this procedure for more details.

Outgas the filaments

  1. Turn on the 32-095/096 x-ray source control and press the Outgas/Activate button. Select both anodes and slowly ramp up each filament to 2 amps. Now, using the ion gauge as a guide, increase the filament current in ½ amp increments until you see some out gassing (usually around 3 amps).
  2. Over the next hour, ramp the filament current up to 4.5 amps on both filaments. Allow the source to sit at 4.5 amps for a minimum of 4 hours, overnight is better.
  3. After the filaments have operated at 4.5 amps for at least 4 hours, ramp them up to 5.0 amps for 30 minutes.
  4. Press the Outgas/Activate button to turn the filaments OFF and let them cool for 15 minutes.
  5. Proceed to high voltage conditioning.

High Voltage Conditioning

  1. Make sure that the filaments are OFF.       Turn the high voltage rheostat on the high voltage control fully CCW and then press the red High Voltage button on the X-ray source control.
  2. Slowly turn the high voltage rheostat CW and bring the high voltage up to 5 kV. Observe the ion gauge for signs of out gassing and slowly bring the high voltage up to 8kV. The red light on the x-ray source control should stop flashing.
  3. Over the next hour or so, slowly bring the high voltage up to 16.5kV.   Observe the ion gauge for signs of out gassing. If you see the pressure rise, back off on the high voltage a little bit and wait a few minutes.   What works best is to bump up the high voltage in 500 volt increments and then to let if sit there while you go do something else.   Periodically come back and bump it up another 500 volts.   You can probably go up to 10kV fairly quickly, but after that you should go more slowly. The higher the kV, the more slowly you should go. Think of a rubber band that is being stretched. The further you pull it, the more likely it will snap.
  4. Note: The vacuum should be in the low 10-9 range when conditioning the high voltage. When the source outgases and the vacuum comes up into the mid 10-8 range, you should wait for the vacuum to go back into the 10-9 range. If the vacuum gets into the high 10-8 range the chances for an arc are good. It is best to bring it up slowly and not get any arcs as opposed to trying to force the outgas process. This takes time, be patient!
  5. Once you have the high voltage up to 16.5kV, leave it sit there for 30 minutes.
  6. Proceed to final conditioning.

Final Conditioning

  1. Turn on the high voltage and set it to 10kV.
  2. Power both filaments and bring up the power to 50 watts on both the Al and Mg anodes.
  3. Observe the ion gauge for signs of out gassing and let the source sit there until the vacuum returns to the low to mid 10-9 range.
  4. Increase the power to 100 watts per anode and increases the high voltage to 11kV.
  5. Slowly step the power up in 50 watt increments and the high voltage in 500 volts increments until you are at 250 watts per anode @ 15kV. This can take several hours.
  6. Leave the source sit there for an hour or more, until the vacuum returns to the low to mid 10-9 range.
  7. Decrease one anode to zero power and increase the other anode to 300 watts @ 15kV. Observe the ion gauge for signs of out gassing.   If necessary, wait for the vacuum to return to the low to mid 10-9 range.
  8. Set that anode power to zero and bring the other anode up to 300 watts @ 15kV and observe the ion gauge.
  9. Once both anodes can run at 300 watts @ 15kV and the vacuum stays in the low to mid 10-9 range, then the source is fully out gassed and can be operated normally.
  10. If you wish to go to 400 watts you will need to run it up slowly from 300 to 400 watts the first time and let it sit there for a while.

Revised outgas procedure for PHI dual anode x-ray sources and single anode mono sources.

Outgassing the filaments and conditioning the anode are essential steps needed to remove adsorbed gases from the filament area of any PHI x-ray source.

Recently I have seen a couple of instances where a 10-610 monochromator source was not properly outgassed and the result was a contaminated anode and very low counts. So degassing the anode is essential for proper operation.

To prevent anode contamination, the anode needs to be degassed per the PHI manual. However I have found that by changing the order of the outgas procedure steps that the amount of time it takes to outgas the source to full power can be significantly reduced.

The manual states that the outgas procedure sequence is as follows:

  1. Outgas the filaments
  2. Condition the high voltage
  3. Degas the anode

But from a practical standpoint it makes more sense to degas the anode before conditioning the high voltage. The reason is that a degassed anode is less likely to arc.

So the faster way to outgas an X-ray soure is:

  1. Outgas the filaments
  2. Degas the anode
  3. Condition the high voltage

Step 1. Outgas the filaments.

You need to outgas the filaments after new filaments have been installed or anytime the system has been brought up to air and baked out. For this procedure it is assumed that the system has been baked out. (The only bake out exception is if you have just replaced the 04-303 ion gun ionizer and backfilled the chamber with dry nitrogen).

  1. Turn on the 32-095/096 power.
  2. On the 32-095/6, press the Blue Out/Act outgas activate button.
  3. Select both filaments
  4. Select the Mg filament (or filament 1)
  5. Slowly increase the amps to 3.5
  6. Select the Al filament (or filament 2)
  7. Slowly increase the amps to 3.5
  8. Let the filaments sit there for a few minutes and then slowly increase each filament to 4.5 amps.
  9. Let the filaments sit at 4.5 amps for a minimum of 4 hours (overnight is best).
  10. After outgassing for at least 4 hours set the filament current to zero on both filaments and turn off the Out/Act outgas button by pressing it one more time.

Step 2 Degas the Anode

  1. Set the beam voltage to 500V and turn it on.
  2. On the 32-095/6, press the Blue Out/Act outgas activate button
  3. Select the Mg filament (or filament 1)
  4. Slowly increase the amps to 3.5 and then monitor the anode current (emission current) meter.
  5. VERY SLOWY increase the filament current until you get 1mA of emission current. Do not exceed 5 amps of filament current. Do not exceed 2mA of emission current.
  6. Monitor the ion gauge vacuum reading and wait until the outgassing comes back down then slowly increase the beam voltage to 1 kV. If necessary reduce the filament current to keep the emission below 2mA.
  7. In steps of 1kV bring the high voltage up to 10kV while adjusting the filament current as needed to keep the emission current below 2mA. Do this over a period of 10 minutes to several hours, depending on how much the anode outgasses. For best results keep the vacuum in the chamber in the low 10-9 Torr range. The higher the pressure from outgassing, the more likely an arc will occur.
  8. Once the anode has been outgassed to 10kV, turn the filament current to zero and set the high voltage to zero. Then switch to the other filament and repeat the procedure.

Step 3 Condition the high voltage

  1. Make sure that the Out/Act button is OFF and that the filament current is set to zero on both filaments.
  2. SLOWLY bring the high voltage up to 10kV while monitoring the vacuum chamber ion gauge.
  3. Step the high voltage up increments of 500V until you get to 16.5kV. When you see some signs of outgassing (the pressure in the vacuum chamber will come up) then back down the high voltage a little bit and wait until the vacuum recovers.
  4. Once you are able to get to 16.5 kV with no arcing, let the anode sit there for at least 20 minutes.

The X-ray source is now ready for normal operation.   For best results, start at a low power and kV such as 100 watts and 10kV.   You can step up both the power and the kV over a period of a few hours based on how much outgassing you see when operating in this mode. Once you are up to full power of 300 watts and 15kv the X-ray source can be brought up to full power quickly.

 

PS RBD Instruments provides all of the replacement parts for the 04-500 and 04-548 15kV dual anode x-ray sources. Contact us for more information.