Prep chamber heater hints

• Prep chamber manipulator heater powered by TDK-Lambda power supply (60 V, 12.5 A) under system controller.
• push small button on far right under digital displays "out" to enable output
• adjust current and voltage knobs. Depending on load either current or voltage limit will control. Green LED near knobs shows which is limiting. 
• Set Sample Heating/Bias Selector switch to "Resistive" to connect the TDK supply to the pBN heater built in to the prep manipulator.
• This heater is ~ 30 Ohm cold, 5 A max current, 100 W max output
• Increase and decrease heater power slowly to avoid thermal shocks
• 1.45 A requires 27.6 V for 40 W, R ~ 19 Ohm (lower when hot). This gave ~ 525 C at thermocouople, sufficient to dewet Au/Si film at ~ 600 C
• There is a thermocouple attached to the sample plate dock. This temperature will be lower than the actual sample temp, and the difference will be greater when radiation is important, > 500 C.
• temperature will depend on sample properties such as emissivity since heating is by radiation coupling

Estimated temperatures for stage and sample vs power

• The side of the sample plate facing the heater must be flat (no sample, screws, clips, wires, etc.
• For simple plates with the sample mounted below, the sample can face the heater
• For this to work, put the sample in the airlock "reversed" or upside down. 
• The sample can be heated
• transfer to the carousel in the analysis chamber upside down. Then use the wobble stick to flip the sample over for inserting in the Auger/STM stage.
• Do not heat samples mounted with spring clips to high temp (> ~ 200 C) as this will anneal and damage the springs. Mount samples with spot welding for high T.
• VT double plates with direct or pBN heating may be inserted in the manipulator stage face up. 
• The plates can be heated using the manipulator pBN heater, or by using the VT heater since the  "fingers" on the manipulator contact the heating terminal.
• Set the selector switch to "direct current" to use the VT heaters.
• The top of the VT heating contact must be 3.6 to 3.7 mm above the bottom of the VT assembly, also the total thickness should be 7.6 mm
• adjust the VT plate if these distances are not correct. Using a badly set VT plate will bend the contact springs.