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Tungsten EM filaments

Manufactured in Agar Scientific’s own production facility to the highest standards using the latest advances in ceramic and metallurgical technologies.

All filaments are manufactured to a high precision in custom engineered jigs to ensure complete accuracy, giving optimum image quality and life expectancy. After manufacture filaments are pre-conditioned by “flashing” under vacuum at temperatures that are greater than the normal operating level. They are then checked for accuracy of centring. Filament assemblies with alignment screws are adjusted under a light microscope to ensure that they are ready for immediate operation in electron microscopes.

Advantages of Agar tungsten filaments:

  • Minimum tip radius to ensure a coherent beam
  • Optimum stability and maximum brightness with a longer lifetime
  • Fully stress relieved for enhanced lifetime
  • Precise dimensions for minimal alignment adjustments

There are filaments available for most current and previous makes and models of electron microscopes, including Carl Zeiss, Hitachi, JEOL, Tescan and ThermoFisher (FEI).

See also our range of Kimball Physics LaB6 cathodes as an alternative to a replacement tungsten filament.

Electron microscope type or filament base

Product number 

Ceramic disc mm

Pin diameter mm

Pin pitch mm
AEI

AGA054

12.0

1.0

6.5
AmRay /AMR (except 1200 series)

AGA086

26.0

1.0

5.0
Cambridge Instruments (except S4-10)

AGA054

12.0

1.0

6.5
CamScan with AEI conversion

AGA054

12.0

1.0

6.5
CamScan with new Tescan Column

AGA047

19.8

1.0

5.0
FEI/Thermo Fisher

AGA086

26.0

1.0

5.0
Hitachi S-Type

AGA042

9.8

1,2

2.7
Hitachi  with Cartridge TM series tabletop
3400N, 3700N, SU1500, SU3500

AGA042C

9.8

1.2

2.7
ISI /ABT / Topcon 2-Pin

23.4

1.2

12.0
JEOL K-Type with metal ring

AGA092

28.0

1.2

8.0
Leica

AGA054

12.0

1.0

6.5
LEO 400 and 1400 Series SEM

AGA054

12.0

1.0

6.5
LEO1450 (except AEI conversions)

AGA043X

19.8

1.0

5.0
LEO TEM

AGA043X

19.8

1.0

5.0
Philips V-Loop (PSEM500/EM200 and later)

AGA086

26.0

1.0

5.0
Tescan

AGA047

19.8

1.0

5.0
Zeiss DSM and TEM

AGA043X

19.8

1.0

5.0
Zeiss EVO

AGA054

12.0

1.0

6.5

The electron source performance table is provided to give additional information regarding the performance and requirements for different type of electron emitters. Tungsten cathodes are still used in the majority in SEMs and in general use TEMs. Improved results can be obtained with LaB6 cathodes, whereas the highest resolution can be obtained with either Schottky or cold Field Emission Sources which can only be used in suitable EMs.

Emitter Type Thermionic Thermionic Schottky FE Cold FE
Cathode Material W LaB6 ZrO/W (100) W (310)
Operating Temp (K) 2700 1800 1800 300
Cathode Radius (nm) 60,000 10,000 <1000 <100
Effective Source Radius (µm) 25 10 0.015 0.0025
Emission Current Density (A/cm2) 3 30 5300 17,000
Total Emission Current (µA) 200 80 200 5
Brightness (A/cm2.sr.kV) 1×104 1×105 1×107 2×107
Maximum Probe Current (nA) 1000 1000 10 0.2
Energy Spread @ Cathode (ev) 0.59 0.4 0.31 0.26
Energy Spread @ Source Exit (eV) 1.5 – 2.5 1.3 – 2.5 0.35 – 0.7 0.3 – 0.7
Beam Noise (%) 1 1 1 5 – 10
Emission Current Drift (%/h) 0.1 0.2 <0.5 5
Operating Vacuum (hPa/mbar) <10-5 <10-6 <10-8 <10-10
Typical Cathode Life (h) 100 >1000 >5000 >2000
Cathode Regeneration (h) None None None 6-12
Sensitivity to External Influences Minimal Low Low High

 

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