R3-A: Diagnostic Rig with RGA Port

ATM → ~10⁻⁹ mbar | Upgraded Gauges (CDG + Hot Cathode) | RGA-Ready | Vent-to-Manifold Topology | Purple = changed from R2-A
R3-A Diagnostic Rig — Component Schematic (Changes from R2-A highlighted) Purple borders/dashes = changed from R2-A | Blue badge = new component CHAMBER ZONE MANIFOLD ZONE (TOPOLOGY CHANGED) HIGH-VACUUM PUMP ZONE CHAMBER R3-CH ~10-15L SS304 (same as R2-A) No vent port here! CDG R3-G-CH UPGRADED ISO R3-V-ISO THROTTLE R3-V-THR ATM VENT R3-V-VENT → MANIFOLD VENT → MANIFOLD (changed!) MANIFOLD R3-PM + RGA port RGA CAPPED NEW PI R3-G-FL GATE R3-V-GATE HC R3-G-HV UPGRADED TURBO R3-P-HV (same as R2-A) FORE R3-V-FORE KF16→25 Rotary Vane R3-P-RP (backing) R3-FLT-EXH ATM R3-A Changes from R2-A 1. Vent → manifold (not chamber) 2. Chamber gauge: CDG (was Pirani) 3. HV gauge: Hot cathode (was cold cathode) 4. RGA port added to manifold (capped) All pumps, valves, piping unchanged
R3-A Specific
Upgraded/changed (purple)
New vent path (orange dash)
RGA port (new)
Components without purple border are identical to R2-A

R3-A Overview

Diagnostic Rig with RGA Port
Target PressureATM → ~10⁻⁹ mbar
HV PumpTurbomolecular pump (same as R2-A)
Backing PumpRotary vane pump (same as R2-A)
Chamber GaugeUPGRADED CDG (was Pirani)
HV GaugeUPGRADED Hot cathode (was cold cathode)
New FeatureNEW RGA port (capped, escalation-only)
Vent TopologyCHANGED Vent → manifold (was → chamber)
Key teaching points for R3-A: Why upgrade gauges? CDG eliminates Pirani's gas-species dependence and thermal drift. Hot cathode extends range to 10⁻¹⁰ mbar (vs cold cathode's 10⁻⁸). The RGA port shows learners how real systems are designed for future diagnostic capability without installing expensive equipment upfront.
Vent topology change: Venting to the manifold (instead of directly to the chamber) is a more controlled approach — atmospheric gas enters the manifold first, allowing pressure equalisation before reaching the chamber. This reduces the risk of pressure shock to sensitive components (turbo pump, gauges).