User Tools

Site Tools


Accelerator Start-up

==== ** Clear all Areas ** ====

1. Verify Initial Machine Voltage setup:

Initial conditions on TPS:

  • SLIT, GVM, CPO, PROBE: All on
  • CPO GAIN: 7-9

Initial conditions on Charging Controller:

  • Key: ON
  • Power: ON
  • CHAIN MOTORS 1, 2, 3: Lights dark
  • CHARGING VOLTAGE dial: 0.10

Initial condition on SHUTDOWN MODULE:

  • POWER: Red Light On
  • CABLE: Green Light On

a. Switch the POWER SUPPLIES to ON, the yellow light should come on. Switch CHAIN MOTORS to ON, lights 1, 2, and 3 should all come on. Begin to increase the CHARGING VOLTAGE while observing the TERMINAL VOLTAGE and the GRID VOLTAGE. DO NOT allow the GRID VOLTAGE to become more negative than -5 VDC. NOTE: If you will be raising the terminal voltage to 3.5MV or higher double click the TANDEMWATCH icon on the alphatross terminal monitor. After approximately 1 minute, the tandemwatch graph should appear on that monitor. Also, check LE tube conditioning by; 1. In the light yellow terminal window, type the command “plot magnet”. This will open a graph that will plot in high sensitivity the LE tube vacuum to watch for tube conditioning. 2. Now, also in the light yellow terminal window, type the command “plotlevacuum”. The plot window should begin plotting a high resolution view of the LE vacuum. If spikes in vacuum are observed when raising the terminal voltage, stop increasing the terminal voltage and wait until the vacuum returns to the baseline value. Continue increasing slowly to the desired terminal voltage while continuously monitoring the LE tube vacuum and pausing when increases are seen. After the desired terminal voltage is reached, the program watching the vacuum can be stopped by entering c/r in the terminal window and the plot can be closed. b. Continue to increase the CHARGING VOLTAGE until you reach the approximate TERMINAL VOLTAGE OR until you begin seeing any corona current. If you begin seeing corona current, move the corona points out until no corona current is seen.

2. Corona Probe Adjustment

After reaching the approximate desired terminal voltage with no corona current present, begin moving the corona points in (set corona current/position to current). Maintain the desired approximate terminal voltage by increasing the UPCHARGE and iteratively move the corona points in while restoring the terminal voltage with the UPCHARGE. The CORONA PROBE CURRENT will rise until it reaches the value set by the BIAS CURRENT. After that, the GRID VOLTAGE will change to keep the CORONA PROBE CURRENT at the set value. The goal is to balance the UPCHARGE and CORONA PROBE POSITION so that you have the desired TERMINAL VOLTAGE and -5 VDC on the GRID VOLTAGE (The GRID VOLTAGE may never reach -5 VDC when running at ultra low Terminal energy, E < 0.300 MV, do the best you can). Do (a) or (b) as needed:

a. Move the CORONA PROBE POSITION “IN” to make the GRID VOLTAGE more negative. This may require you to adjust the UPCHARGE to maintain TERMINAL VOLTAGE.

b. Move the CORONA PROBE POSITION “OUT” to make the GRID VOLTAGE less negative. This may require you to adjust the UPCHARGE to maintain TERMINAL VOLTAGE.

c. If the low energy cup current is > 5 uA, put the beam into the high energy farady cup and tune for maximum current before proceeding to step 3.

3. Establish Control

a. Set the TERMINAL VOLTAGE Dial to the desired value. The dial is 2 turns per MV (set the dial to twice the GVM you want). You may have to add some upcharge after setting the dial.

b. Slowly raise the CONTROL GAIN to 2-3 for low current beams, around 5 for high current beams. The system is now controlling in GVM mode.

c. Make fine adjustments to the TERMINAL VOLTAGE Dial to reach exactly the desired GVM value. Very fine adjustments to the terminal voltage can be made using the FINE control located coaxial to the BIAS CURRENT control with a full range of 1.5 KV.


e. Do accelerator header and collect the NMR frequency and analyzer magnet current values.

4. Beam Transport

a. Use the magnet predictor tool and set Quad 1 to the predicted value. Do not make large abrupt changes to the Quad 1 current. If a large abrupt change in current is attempted, the power supply may begin oscillating. To stop this oscillation, run the current slider to zero then re-adjust to the desired current at a slower non-abrupt rate.

b. Tune beam and send it around the properly configured Analyzing Magnet.

c. You may need to make adjustments to the TERMINAL VOLTAGE dial to get the terminal to the proper energy for transmission around the magnet and fairly balanced current on the slits.

d. When current is present on the LE and HE Slit current meters you may then switch the Control Mode to AUTO (middle position) and the SLIT control light should illuminate. If there is instability in slit control you may try raising the CONTROL GAIN more. If the slit currents are not balanced when in slit control, make slight adjustments in the CHARGING VOLTAGE to balance the slit currents.

e. When in AUTO control the machine will go back to GVM control anytime the beam is interrupted.

5. Dipole Magnet Setup Instructions

a. Confirm that the Heinzinger power supplies are powered ON in the Small Target Room with the following LED's illuminated: Red “ON”, and Green “Remote”. If Off, Press the “Local/Remote” button to “Local”; then “Stby” then “On”; then “Local/Remote” to “Remote”.

b. If not already visible on the control room computer screen, start the appropriate software GUI's using the “Restart” button for “analyzer, switcher, swinger, or tweaker” magnets.

c. In the “Switcher_hz422” and “Analyzer_hz422” GUI windows, magnet beam deflection (left/right) is indicated on the “Magnet Current” line indicated as beam “left or right”. The polarity can be toggled using the “Polarity” button located to the right of the “Lock” button. When the “Polarity” button is pressed, the magnet current will automatically be set to zero and the polarity will reverse.The “Swinger_hz422” and “Tweaker” have no polarity reversal button.

d. Run the slider to the desired current.

playground/startup.txt · Last modified: 2023/09/21 06:28 by carter