Troubleshooting

Beam dump happens

When Beam dump unfortunately happened, there will be no beam and the valves will automatically close. Check the chat panel and Public website for machine status (should be 500 mA for small ring) for updates.

Once the beam is restored: Reopen the valves before resuming measurements.

Order to open valves in front end: V1, BS-01, HA-01 Order to close valves in front end: HA-01, BS-01, V1

_images/valve_front_end.png

  • HA-01 and BS01 are used for blocking beam, and V1 is used for isolating the vacuum of storage ring.

  • The beam is opened or closed in this order to prevent direct illumination of beam on V1, which is metal and might melt under illumination.

Beamline software gets stuck

If the beamline staff are not around, try:

  • Restart in Astor

  • Kill the process using the sardana-restart script

  • Calling the Floor Coordinators

When HV switches off due to an arc

  1. Ramp down the cathode current by turning the knob counterclockwise (Gun control unit - Filament current: 1.75 A to 0 A)

  2. Put the power supply unit of the cathode （Gun control unit）, the electron analyzer （Electron analyzer control unit）, the aberration corrector （Mirror control unit） and the start voltage （Start voltage control unit） into the “local” control mode by rotating the knob to the right. （Status 1 for switch on HV rack: Every unit stands by at local mode.）

  3. Switch on the HV rack by pressing the round green button at the bottom of the HV rack

  4. Wait for 10 to 20 seconds

  5. Put the power supply units back to the “remote” control. The LED displays of the individual power supplies should go to the values close to the values in the LEEM2000 program. （Status 2 for 20 kV: Every unit stands at remote mode, except Sample heater control unit! Power supply unit can be left at either local or remote mode.）

  6. Ramp up the cathode current to 1.75 A slowly (in 10 to 20 seconds for instance) （Gun control unit - Filament current: 0 A slowly to 1.75 A）.

  7. Ramp up the main 20 kV until the pressure is recovered, i.e., when the pressure is below 1x10^-9 torr in the main chamber.

If there is any uncertainty that another arc may occur, perform Step 7 before Step 6. Carefully monitoring the pressure during adjustments.

Scangui crashes