Analyser and Ion Source Service for ULVAC HELIOT Leak Detectors

The mass spectrometer analyser is the core detection element of every ULVAC HELIOT helium leak detector. It consists of the ion source, the 90° magnetic deflection sector, and the ion collector (Faraday cup). The ion source is the only consumable part in the analyser and the primary cause of sensitivity loss. This page covers ion source inspection, replacement, and full analyser service for all HELIOT models.

The Ion Source in HELIOT Instruments

How the Ion Source Wears

The filament is the primary wear element. It emits electrons by thermionic emission (resistive heating). Over time:

• Filament thinning: gradual loss of filament material causes emission instability and eventual break.
• Contamination: process gases, solvents, organic compounds, and particulates deposited on the ion source surfaces change the local electric field, reduce emission efficiency, and alter mass tuning.
• Ion lens degradation: deposited films on lens electrodes shift focussing; the instrument may lose signal while the vacuum system is otherwise normal.

The HELIOT 900 series has two filaments (A and B). Automatic filament switchover occurs if one filament fails. When both filaments are consumed, the instrument stops detecting and an ion source replacement is required. Some HELIOT models flag which filament is active in the tablet display.

Symptoms Requiring Ion Source Investigation

Symptom	Probable cause
Sensitivity low — internal calibrated leak test fails or reads low	Ion source contamination or filament wear; confirm vacuum OK first
High and unstable baseline leak rate reading	Ion source contamination; helium trapped in analyser; contaminated analyser
Cannot select filament A or B; instrument stops with ion source error	Both filaments broken — IS-BA1 replacement required immediately
Slow response time (leak rate lags probe movement)	Ion source contamination causing sluggish ionisation; analyser cleaning may help
Instrument operates, but calibration factor outside normal range	Ion source degradation changing effective sensitivity; may need replacement and recalibration
Short ion source lifetime (e.g., failing within months)	Check for contaminating process gas, solvent, or particulate ingestion; investigate root cause

Ion Source Replacement Procedure (Overview)

The IS-BA1 is designed for replacement without tools in the HELIOT 900 series. The procedure is covered in the HELIOT 900 operator manual and built into the tablet controller’s maintenance guide. The general sequence is:

1. Vent the instrument to atmospheric pressure through the instrument’s controlled vent procedure.
2. Remove the front panel (tool-free on HELIOT 900 series).
3. Disconnect the IS-BA1 electrical connector.
4. Rotate and withdraw the IS-BA1 cartridge.
5. Inspect the analyser body bore for contamination; clean if required.
6. Insert the new IS-BA1 cartridge; rotate to lock.
7. Reconnect the electrical connector; verify polarity.
8. Replace panel; start instrument.
9. Allow instrument to pump down; verify filament emission in tablet display.
10. Perform internal calibrated leak check and verify sensitivity meets specification.
11. Adjust calibration factor if required.

Note: Step-by-step detail depends on instrument model and software version. We perform ion source replacements as part of on-site service visits and train operators on the procedure.

Analyser Cleaning

When contamination has spread to the analyser body, quadrupole (if applicable), ion collector, and deflection sector, replacing only the IS-BA1 may not restore full performance. In these cases the analyser requires cleaning. Analyser cleaning involves:

• Controlled venting and disassembly of the analyser section
• Solvent cleaning of analyser body surfaces and electrodes (compatible solvents; no abrasive)
• Drying under vacuum (bake-out if available)
• Reassembly with clean tools and handling
• IS-BA1 installation
• Pump-down and full calibration verification

Analyser cleaning is more involved than ion source replacement and should be performed by a qualified service engineer. We carry out analyser cleaning during on-site service visits and at customer sites by arrangement.

Turbomolecular Pump — Role in Analyser Performance

The 31 L/s turbomolecular pump (TMP) creates the high-vacuum environment needed for mass spectrometer operation. If the TMP has reduced speed, contamination, or bearing wear, analyser performance degrades even with a new IS-BA1. We always check TMP speed, temperature, and bearing condition during analyser service. A new ion source cannot compensate for a degraded TMP.

What We Do During Analyser and Ion Source Service

• Filament status check (A/B condition, emission current)
• Internal calibrated leak sensitivity test
• Baseline background measurement
• IS-BA1 visual inspection through analyser port
• IS-BA1 replacement if indicated
• Analyser body inspection for contamination
• Analyser cleaning if contamination is present
• TMP speed, temperature, and bearing noise check
• Pirani gauge reading verification (fore-line and analyser pressures)
• Post-replacement calibration verification with reference leak
• Response time measurement
• Calibration factor documentation

Ordering IS-BA1 Ion Sources

We supply IS-BA1 ion source cartridges for all applicable HELIOT models. We do not recommend purchasing ion sources from unknown sources without confirming part number compatibility. Contact us with your HELIOT model and serial number and we will confirm the applicable IS-BA1 part number for your unit.

Request Analyser or Ion Source Service

Email: mail@ulvacheliot.com

Include: HELIOT model and serial number, symptoms (sensitivity loss, filament error, baseline instability), and your facility location. We will respond within 1–2 business days.

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