Kimball Lanthanum Hexaboride (LaB6) Cathodes for Electron Microscopes

Heating current path through precision-machined, single-piece carbon rod and mounting strips; sub-base provides rigidity and easier mounting.

The Kimball Physics ES-423E (Extended Life) Lanthanum Hexaboride Cathode is a high performance, resistively heated, thermionic electron source. It is currently used in many electron optical systems: SEM's, TEM's, microprobes, electron lithography systems, etc. This superior LaB6 source gives a greater brightness (higher current density), lower energy spread (better resolution) and a longer lifetime than standard tungsten filaments. Lifetimes in excess of 6 months of continuous operation are regularly achieved in commercial SEM's and TEM's with suitable gun vacuum (10-7 torr or better). The standard emitter is a 15µm diameter <100> oriented single crystal surface mounted on the end of a single piece, stress-free, carbon heater rod, held in place by a carbon ferrule. The single piece carbon heater rod has a precision machined 100µm slot along the axis to direct the heating current; the result is no high temperature carrying high temperature joints. The design together with a high degree of symmetry keeps mechanical movements small which results in increased stability. The small physical size fits most Wehnelt cylinders with ease. Another advantage of the Kimball Physics LaB6 cathode is the reduced material loss which means less Wehnelt contamination; again this results in greater stability compared to other types of LaB6 cathodes.

For further information see Technical Bulletins at bottom of page.

For use in:

• Scanning Electron Microscopes
• Transmission Electron Microscopes
• Electron Micro Probe Analyzers
• Electron Lithography Systems
• Electron Accelerators

Unused LaB6 crystal mounted on carbon heater rod, and held in place by precision carbon ferrule; note roundness and smoothness of microflat.

LaB6 crystal mounted on an AEI/Leica base

Featuring:

Extended lifetime

• Thousands of hours in clean vacuum
• Guaranteed life (measured in surface loss)
• Guaranteed against mounting structure failure

Designed with built-in stability

• Thermal / chemical / mechanical / electrical stability
• Precision machined carbon mounting
• High over-temperature tolerance

High brightness/low energy spread

• Oriented single-crystal
• Best quality/high purity material
• Low work function
• Improved resolution

Accurate microflats

• Superior optics/controlled source size
• Standard diameters available

Dimensions for EM Filament Bases (for Tungsten/Lab6) Filaments