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Section 6.3: Turning on the Beam
Table 6.3: Problems with BEAM and ACCEL
PROBLEM
DESCRIPTION
POSSIBLE PROBLEMS AND SOLUTIONS
Beam current zero.
1. Discharge is not started or is out – Check discharge operation
(Table 6.2)
2. Faulty connection – Check cable and feedthru connections (Table 6.5).
3. Possible power supply problem – Have power supply serviced.
Beam current lower
than normal
1. Gas flow is lower than expected – Check gas flow and operation.
2. Discharge current is too low – Check discharge operation (Table 6.2)
3. Cathode is newer than an older one (Manual mode).
Beam current higher
than normal
1. Screen grid is electrically shorted – Check body electrical connections.
Look for signs of plasma shorts, coated insulators and electrical lead wire
proximity issues.
2. If both accel and beam current are high - Check the grid alignment
and spacing. Check for accel to screen grid shorting (Table 6.5)
3. Anode is electrically shorted – Check anode connections. Look for
signs of plasma shorts inside source, coated insulators and electrical lead
wire proximity issues.
4. Screen grid has debris or flakes – Clean screen grid.
5. Discharge current is too high – Check discharge operation (Table 6.2).
6. Gas flow is higher than expected – Check gas flow and operation.
7. Cathode is older than a newer one (Manual mode).
Accel current zero.
1. Discharge not started or is out – Check discharge operation (Table
6.2)
2. Faulty connection – Check cable and feedthru connections (Table 6.5).
3. Possible power supply problem – Have power supply serviced.
Accel current lower
than normal
1. Accel grid has a faulty electrical connection – Check connections.
2. Gas flow is lower than expected – Check gas flow operation.
Accel current higher
than normal
1. Accel grid is electrically shorted – Check accel electrical connections.
Look for signs of plasma shorts inside the source, coated insulators and
electrical lead wire proximity issues.
2. If both accel and beam current are high - Check the grid alignment
and spacing. Check for accel to screen grid shorting (Table 6.5)
3. Accel grid insulators are coated – Check insulators and clean / replace.
4. Accel grid insulators are coated – Perform high-pot test (Table 6.5).
5. Gas flow is higher than expected – Check gas flow operation.
6. Beam voltage is too low – Examine the source run data.
Arcing
1. Debris or flakes are in proximity to the grids – Check and clean the
screen and accel grid.
2. Accel grid is coated with dielectric material – Clean the accel grid.
3. Grids have contamination – Clean grids ultrasonically in Micro-90 and
water. Rinse and wipe with alcohol. Bake grids under a heat lamp to
remove water vapor. Wipe with alcohol and blow with dry nitrogen.
4. Source was not warmed up long enough – increase warm up time.