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playground:alphatross [2020/06/11 08:41]
jacobs
playground:alphatross [2022/06/08 09:05]
leblanc Same as last revision, which didn't have any changes.
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-==== NEC Alphatross RF Source Instructions ==== +====== NEC Alphatross RF Source Instructions ======
-  +
-**  __START UP__ **+
  
-** In the Vault **+=== START UP ===
  
-  - LE Extension vacuum must be good as evidenced by Ion Gauge controller with orange displays on magnet. +== In the Vault ==
-  - Source vacuum must be good as evidenced by Ion Gauge controller with blue displays in 19" rack. +
-  - Unground alpha source and hang shepherd'​s hook on concrete wall conduits, close gate. +
-  - Go around and unground sputter source, hang shepherd'​s hook on gate, and close gate.+
  
-** In the Control Room ** 
  
-  - Source camera must have a view of the faraday ​screen on the blue box of the source head.  ​+  ​- Verify LE Extension Vacuum - indicated by Ion Gauge controller with orange displays on magnet. 
 +  - Verify Source Vacuum - indicated Ion Gauge controller with blue displays in 19" rack. 
 +  - Unground alpha source and hang shepherd'​s hook on concrete wall conduits 
 +  - Close Alphatross gate and verify interlocks OK by observing indicator light. 
 +  - Set buncher tube selector switch - see [[playground:​buncher|Buncher Setup and Use]] 
 +  - Unground sputter source [optional], hang shepherd'​s hook on gate. 
 +  - Close Sputter source gate. 
 + 
 +== In the Control Room == 
 + 
 +  ​- Source camera must have a view of the Faraday ​screen on the blue box of the source head.  ​
     - To gain control of the source camera: On the joystick unit press "​2"​ then "​CAM"​ to specify the camera.     - To gain control of the source camera: On the joystick unit press "​2"​ then "​CAM"​ to specify the camera.
-    - Use the joystick and "​TELE"​ or "​WIDE"​ to create a view of interest. +    - Use the joystick and "​TELE"​ or "​WIDE"​ to create a view of interest. Pressing "​6"​ followed by "​Call"​ will move and zoom the camera appropriately.  
-  - If not already present, launch the Alphatross software on the source computer. +  - If not already present, launch the Alphatross software ​(Version 6.0) on the source computer
-  - In prompt succession press the "​on"​ buttons for: Water Cooling, ​Source Powerand He4 Gas.+  - Press the "​on"​ button for Water Cooling. ​ The water cooling system: 
 +    - operates independently of the source and the HV interlocks. ​  
 +    - contains a flow switch that must be closed in order to start the source. 
 +    - provides heat to prevent Rb freezing. 
 +    - provides cooling to the magnet in the source
 +  - In prompt succession press the "​on"​ buttons for: Source Power and He4 Gas.
     - These actions start a 60 second timer on the RF supply and set initial conditions on the Magnet and Mass Flow Controller.     - These actions start a 60 second timer on the RF supply and set initial conditions on the Magnet and Mass Flow Controller.
-    - After 60 seconds the RF power startsgives a reading on the meter above the faraday ​screen, and hopefully ​the plasma ​will ignite ​giving an intense white glow.  ​It is bright enough ​to illuminate ​the faraday screen if not looking directly at it in the mirror+    ​- A dim neon light will illuminate behind the Faraday screen on the source box. 
-  - Plasma or not, raise the Magnet to 4 A, maybe the plasma ​will ignite+    ​- After 60 seconds the RF power starts.  This: 
-    - Monitor ​the Ion Gauge pressureit should remain less than 4 x 10-6 Torr while setting the Probe.  ​It should settle to around 2 x 10-6 or less when done+      - gives a reading on the meter above the Faraday ​screen 
-    - Raise the Probe Voltage to 3 KV as a start, this might be enough ​to get the plasma going+      - may ignite ​the plasma giving an intense white glow. 
-    - If there is still no plasma try raising the Mass Flow setting ​to as much as .5 SCCM to inspire ignition and then return to .35 SCCM.  +  - Raise the Magnet ​to 4 A (may ignite ​the plasma)
-    **This is a pause point for source clean up, can run like this for days, should reduce ​probe current ​over time** +  - If the plasma has not ignited 
-    Monitor the Probe Current, maintain 3 mA +/1 mA, and continue raising the Probe Voltage until it reaches 6.5 KV  ​ +    - Raise the gas flow until the plasma ​ignites. ​ This should be less than 1 SCCM in most instances
-  - Set the Oven Voltage to 87 V, wait ten minutes. ​ After 10 minutes the Oven Temp should be around 150 C+    - Quickly lower the gas flow back to 0.350 SCCM (or your desired operating rate). 
-  - Set the Extractor Voltage to 5.5 KV and the Bias Voltage to a value that gives the desired injection energy ​less (6.5 + 5.5)Beam yield seems to increase with injection ​energy above 30 KeV.  ​Suggest trying 41 or 53 KeV settings if pulsing+  - Set the probe voltage by: 
-    You may now be able to look at negative beam in the source faraday ​cup (#7 on the FC meter).  ​Its not clear if this is a useful endeavor+    - Monitoring ​the Ion Gauge pressure
-    - Beam yield will increase as Mass Flow is reduced, expect optimum yield at //around// .2 SCCM+      - it should remain less than 4 x 10-6 Torr.  ​ 
-    Optimize negative ​beam yield by tuning Extractor Voltage, ​Focus Voltage, and Mass Flow. Adjust Bis Voltage accordingly if an exact injection energy is required for P&​B. ​ Expect little or no Focus Voltage+      - Operating range is around 2 x 10-6 or less. 
-  - Use software buttons to take out faraday cup and open gate valve. +    - Raise the Probe Voltage to 3 kV. 
-  - Set Lens A to 10 KV and source ​Einzel Lens to 15 KV initially and use the inflection magnet to pass beam on to the LE faraday ​cup.  Tune both lenses and magnet for optimum conditions. ​ The BPM may be useful too+      - Check probe current ​to insure that it is less than 4 mA
-  - You may need to re-tune with Extractor, Bias, and Focus Voltages and Mass Flow setting. ​ Each voltage tune will affect the inflection magnet. +    - Continue ​raising the probe voltage ​to 6kV
-  The maximum Oven Temperature is around ​190 C, seems to be around 91 Volts.  ​At this point Rb begins ​to escape ​the chamber and the beam becomes twitchy.  ​If the beam is unstable briefly reduce ​the Oven Voltage until stabile beam and return Oven Voltage ​to a  slightly lesser value.+      Maintain ​probe current ​less than 4mA.  High probe current may indicate: 
 +        Source is still grounded. 
 +        ​Source is dirty and requires service
 +  - Set the Oven Voltage to 80 V. 
 +  - Set Extractor Voltage to 5kV. 
 +  - Set Bias Voltage to a value that gives desired injection energy. ​ ​Typical values are at least 53keV. 
 +    - Injection energy is displayed in the upper window. 
 +    - Injection ​energy ​is the sum of Probe, Extractor, and Bias voltages. 
 +    - Beam yields improve ​above 30 keV. 
 +  - Set the Focus Voltage to 5.5 kV 
 +  Set the Faraday ​cup meter to position 7 (Alphatross cup). 
 +  - Tune for maximum __stable__ beam. 
 +    - Primary adjustment at this stage seems to be focus voltage
 +    - Current may be on the order of 30 μA. 
 +  - Set Einzel Lens to 20 kV. 
 +  - Wait until the Oven Temperature ​is at least 160 C, 10 - 20 minutes
 +  Tune for maximum stable ​beam using 
 +    - Focus Voltage 
 +    - Mass Flow - optimum around 0.25 SCCM. 
 +    - Verify ​injection energy is at desired value
 +  - Open source ​gate valve. 
 +  - Take our source ​Faraday ​cup. 
 +  - Move FC selector switch ​to position 1 (LE cup) 
 +  - Tune beam into FC 
 +    - Set inflection magnet ​(typical values are around 1.2 A) 
 +    Typical beam currents at this stage are around ​500 nA. 
 + 
 +  * Oven Voltage can be increased to give additional beam current.  ​It IS possible ​to boil all of the Rb out of the oven.  ​When this happens, ​the oven temperature will rise and the chamber temperature will fall.  Decrease the oven voltage ​and allow Rb to accumulate within the oven.
  
-** __SHUT DOWN__ **+===SHUT DOWN===
  
   - Click the software button "​Automatic Shutdown"​   - Click the software button "​Automatic Shutdown"​
-  - Confirm you wish to quit be answering "​y"​+  - Confirm you wish to quit by answering "​y"​
   - Walk away.  ​   - Walk away.  ​
   - ** Do not open the source gates until the process is finished **   - ** Do not open the source gates until the process is finished **
playground/alphatross.txt · Last modified: 2022/06/08 09:05 by leblanc