UHV furnace

• NAME
• How to put the sample in.
• How to anneal the sample.
• How to get the sample out.
• Eurotherm settings

NAME

How to put the sample in.

1. Make sure the vacuum chamber is on atmospheric pressure. This is the case when the valve of the vacuum chamber is open and the differential pressure meter indicates zero.
   
   
2. Open the flange with the butterfly-nuts. Remove the flange horizontally, since the outer shield of the furnace is mounted on the back-side of the flange.
   
   
3. Cover the space directly under the furnace with a piece of paper in order to prevent that the sample falls accidently into the turbopump.
   
   
4. Insert the sample into the furnace using a pair of tweezers.
   
   
5. Remove the paper and close the flange.

How to anneal the sample.

1. Turn on water cooling for pump and furnace.
   
   
2. Close the valve at the backside of the vacuum chamber, next to the differential pressure meter.
   
   
3. Switch on the pumps by pressing the button pumping unit on the power supply of the turbopump.
   
   
4. Make sure that the turbopump reaches full speed.
   
   
5. Start degassing by pressing the button heating on the power supply of the turbopump.
   
   
6. Program the Eurotherm temperature controller (see Eurotherm settings). It is best to heat the sample in two steps, because there will be an unavoidable temperature overshoot (~10 °C at 920 °C).
   
   
7. Wait until the pressure is sufficiently low (10^-8 mbar is possible in 24 hours).
   
   
8. Turn on the power supply of the furnace.
   
   
9. When the temperature is stabilized on the preset value, you can gradually increase the temperature by using the button UpArrow on the temperature controller.
   
   

How to get the sample out.

1. Switch off the power supply of the furnace and wait until the furnace is cooled down to below ~100 °C.
   
   
2. Switch off the turbopump.
   
   
3. Switch off the degass heating.
   
   
4. Switch off the pressure meter.
   
   
5. Check the pressure in the small N2 resevoir. If the pressurs is almost zero, you can let in gass by opening the big yellow valve.
   Make sure that the pressure is not too high.
   
   
6. Open the small valve on the resevoir to fill the tube that connects the vacuum chamber and the N2 resevoir.
   Make sure that the pressure is not too high.
   
   
7. Open the valve at the back of the vacuum chamber slowly, and let N2 gass into the vacuum chamber.
   Keep the differential pressure close to zero.
   
   
8. Repeat steps 6 and 7 until the tube maintains pressure and the differential pressure meter indicates zero.
   
   
9. Open the flange, cover the hole under the furnace and take the sample out.

Eurotherm settings

    Sp(°C)  Pb      ti      td      cbl     cbh     Hl

     100   17.4    1130     off     off     off     20
     200   18.4     544     off     off     off     20
     300   13.1     635     off     off     off     20
     400    1.2     271     off     off     off     25
     500    1.1     179     off     off     off     50
     600    0.8     124     off     off     off     50
     800    2.5      82     off     off     off     75
    1000    4.3      75     off     off     off    100