No ion beam, electron energy is zero on GCT- WKB9749

SYMPTOMS

• No beam
• Ion energy readback = 0
• Trap current readback = 0
• Emission current readback maxed out (typically = 5000 µA)

ENVIRONMENT

• GCT Classic
• GCT Premier

CAUSE

The shield on the inner source EI filament is shorting to the inner source ion block or outer ion chamber.

FIX or WORKAROUND

1. Vent and remove inner source.
2. Investigate where the short to ground is located and rectify.

• Determine if the filament shield is distorted. Replace filament if it is.
• Determine if the ion exit slit is bent back toward the filament shield. Straighten the exit slit if necessary.
• Determine if the magnet caps have slipped on the outer source. Push the cap back into place if needed.

3. Replace the inner source, pump down, and check for an ion beam.

ADDITIONAL INFORMATION

Filament shields can distort when they are heated by the filament in Operate. This distortion can be enough to create a short circuit in Operate that is not present when the inner source has cooled down. For this reason, measuring the filament continuity to ground at the feed-through will not always find the problem.

See also WKB62609 for conditioning filaments.

See also WKB11064, WKB124360, and WKB124362 for related problems.