LHRS for GMn

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Nominal Settings

• When starting a shift, it is prudent to verify that the magnets are set correctly. If it's not right, consult the RC. Currents should be within about 0.5 A of the values. Also, note that "readback" values are slightly different from "set point" values.
• The LHRS dipole NMR doesn't lock. Need to set manually to match the field value (iterative procedure, see the instruction below)
• Below are set points. Readbacks will be a bit lower.

Setting the LHRS Magnets

If one can not reset the magnet remotely: Do NOT go into the hall to reset by yourself. Contact RC and then tech on-call/magnet expert. Regulators for Q1, Q2, Q3 are always OFF. Q1, Q2, Q3 magnets will be set by current.

0. Clear all faults (if there are still problems with flows or liquid levels there is no point ramping back up to crash again).

Dipole

1. Regulator OFF (because of NMR multiplexer problems. Directions to proceed are here)
2. Set the current to 744.0 followed by the procedure
3. Wait until the field is stable (watch the strip chart). Check that the Hall probe matches the target value (XYZ ± XYZ) when it is stable
4. Adjust the current if they do not match. Repeat step 3.

If the dipole turns off, to turn it back on:

1. Zero
2. Reset
3. On
4. Type in the desired current and hit enter

If this does not work, notify the RC.

Quadrupoles

1. Check that the regulator is OFF for Q1, Q2, and Q3
2. Turn on the Q1 power supply if it is not ON already
3. If turning a quad magnet down, we do not need to cycle the magnet. Just set the set point.
4. If turning a quad magnet up, it must be cycled to always follow the same hysteresis curve
   1. Q1: The LQ1 should be run to 900 A. Let it stay at 900 A for roughly 2 minutes before loading the desired set point.
   2. Q2: The LQ2 should be run to 1600 A. Let it stay at 1600 A for roughly 2 minutes before loading the desired set point. First ramp to 100 A. If it does not trip, then ramp to 1600 A.
   3. Q3: The LQ3 should be run to 1600 A. Let it stay at 1600 A for roughly 2 minutes before loading the desired set point.

Monitoring

Bringing Up the GUI

The LHRS GUI can be found at:

OPS Menu -> EDM (HLA) -> Hall A -> Tools Display

Checking Polarity

LHRS dipole polarity changes require an access. The rest can be changed with the power supply GUI.

One should check the polarity with Gaussmeter. The Hall probes should read positive for positive particles and negative for negative particles (with current in the magnets)

show image

Checking and Controlling Drifts

Notes from Javier

Legacy Pages

• LHRS