AGA0691-9020, LaB6 Filament 90/20 on FEI XL30 Base

• High current, high brightness, single crystal
• Emission current densities up to 30A/cm2
• Range of emission surface sizes
• Long lifetimes
• Operating pressure <10-7 torr

Kimball Physics single crystal lanthanum hexaboride (LaB6) cathodes are available for most makes of electron microscopes and other electron beam instruments where a suitable gun vacuum in the region of 10-7 Torr is attainable. The filament heater can then be driven by the normal power supply of the microscope.

Brightness above 1 x 106 Amp/cm2 steradian is achievable.

For SEM applications, the higher brightness provides better imaging resolution and improved efficiency for microanalysis. For TEM, the low energy spread of the LaB6 filament is particularly advantageous for high resolution imaging. Alternatively, LaB6 filaments may be used where a long filament life is important; lifetimes in excess of six months continuous operation are regularly achieved.

ES423E series with 90° cone and 15µm microflat
The ES423E style 90/15 cathode is the standard LaB6 crystal filament, ground with a 90° cone, terminated with a truncation of 15µm diameter. This is the standard style of filament recommended for long life, stability and uniformity.

ES423E series with 90° cone and 20µm microflat 
The ES423E style 90/20 series of LaB6 filaments are designed to be used in scanning electron microscopes that normally operate with a high emission current in the range of 60 - 100µA. The 90° cone is terminated with a 20µm diameter microflat. A long lifetime of this filament can be achieved providing a good gun vacuum is maintained.

ES423E series with 60° cone and 6µm microflat 
The ES423E style 60/06 filament has the tip of an ES423E LaB6 crystal ground with a 60° cone, terminated with a polished truncation of 6µm diameter. This type of filament can provide a higher brightness than filaments with larger truncations. The main application of this style of filament is in high resolution TEM, where the total beam current is frequently restricted to minimise electron energy spread. With this filament, adequate axial brightness is attainable at very low emission currents. As a consequence of achieving the higher brightness, the effective lifetime of this filament is found to be slightly less than a conventional 90-15 style filament.

 LaB6 Cathode Technical Datasheet