General Informations

All the feedthroughs described in this section are totally Amagnetic. V.L.T.- S.r.l. offers standard ceramic- - to - metal vacuum brazed component products for H.V. and U.H.V. applications. All components are offered in a variety of flanges mounting and have the following common characteristics:

  • Insulator : Glazed Alumina 97%

  • Metal parts : AISI 304L/316L, Cupper OFHC, Titanium.

  • Conductors : Copper OFHC, AISI 304L

  • Flanges : DN-KF, DN-ISO-K, DN-CF

  • Operating temperature : 450°C

  • Leaktightness : better then 10-10 mbar l/s

Please note VLT is equipped to produce custom ceramic – to – metal components for almost any application.

The following components are included in the catalogue:

  1. Electrical Feedthronghs : Power, Instrumentation, Coaxial.

  2. Viewports

  3. Ceramic Breaks

  4. Special components

  5. Thermocouples

1) Electrical Feedthroughs

- Power is this a special serie of electrical feedthronghs completely amagnetic, it includes the following models:

•  FT04, FT06, FT08 FT12, FT20, FT30, FT40.

- Current values from 1 to 180 Amps
- Voltage Values from 5 to 23 KV

FT012 + FT04 (KF16)

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•  HCF series High current feedthronghs models HCF10, HCF20, HCF38.

- Current values from 140 to 600 Amps
- Voltage values from 5 to 6 KV.


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• HFT series High voltage feedthronghs models HFT04, HFT06, HFT08, HFT12, HFT 30, HFT40, HFT50, HFT70, HFT150.

- Current values from 1 to 400 Amps
- Voltage values from 10 to 100 KV.


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- Instrumentation coaxial feedthronghs, designed to respond to the standard coaxial connectors for R.F., all feedthronghs are completely amagnetic and rated for cryogenic temperatures. They are constructed of vacuum grade materials with High purity Alumina ceramic dielectric with AISI 304L metalic parts weldable on flange KF, CF, ISO-K standard. They are available in single or Double Ended geometries Atmosphere standard air side coaxial connectors are supplied. The following types are included in the catalogue:

• BNC (Bayonet Naval Connector) coaxial connectors, used for low power transmission lines. Grounded shield: 500 V, 3 Amps., Impendence rating is not constant.


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• MHV Miniature High Voltage coaxial connectors, similar to BNC type but rated for medium power and higher voltage requirements. Grounded shield: 5000V, 3 Amps., Impendence rating is not constant.


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• N Respond to MIL specification, rated for medium power, higher frequency (DC to 6 GH2) Grounded shield: 5000V, 5 Amps., 50 Ohms.


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• SMA 50 Sub – Miniature, rated for low power, High frequency (DC 8 GH2), Impedence matched feedthronghs, grounded shield 1500 V, 1 Amps, 50 Ohm.


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• SC50 Respond to MIL specification, rated for medium power, High frequency (DC to 8 GH2).
Grounded shield: 5000V, 5 Amps., 50 Ohm.

SC 50

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2 ) Viewports

VLT offers a wide choice of Viewports in non magnetic assemblies mounted on CF, KF and ISO-K flanges.



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  • Standard sapphire viewports:

- Plane parallel windows free optical path up to 50mm. diameter
- UV grade transmission range 0,25 to 4,50mm.
- Optical finish
- Crystal orientation normal to optical axis or 90° orientation
- Anti-Reflection coatings supplied on request. Note that the A.R. coatings is applied after brazing. The A.R. coating can be of Single Layer or Multi – Layers.

  • Viewports with other optical materials as Fused Silica. (UV Grade), Quartz (SiO2), Magnesium Fluoride (MgF2) can be supplied on request..

3 ) Amagnetic Ceramic Breaks

VLT Vacuum Ceramic Breaks are designed for applications which require high voltage insulation in High Vacuum and Ultra High Vacuum use. Small ceramic breaks can be supplied for Cryogenic applications. All Ceramic Breaks are constructed with vacuum grade materials, AISI 304L, High purity Alumina and vacuum grade brazing alloys. As standard VLT can supply vacuum flanged Ceramic Breaks from CF 16 to CF 200, voltage rating from 6 to 10 KV, temperature rating up to 450°C , any others type of vacuum flange can be supplied on request.



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The catalogue includes the following series:

  • CB 22 flanged with CF 16 or KF 25

  • CB 41 flanged with CF 40 or 63 ISO-K

  • CB 73 flanged with CF 63 or 63 ISO-K

  • CB 111 flanged with CF 100 or 100 ISO-K

  • CB 150 flanged with CF 200 or 200 ISO-K

4 ) Thermocouples

VLT present a large selection of High and Ultra-High-Vacuum thermocouples, of the Cladding type, suitable also for temperature measurements in closed environment, where a perfect leaktightness is required. The principal feature of the VLT production is that the thermocouples are supplied already assembled with their flanges and/or feedthrounhgs. In this way the thermocouples are not only very compact, but they are also immediately usable.



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Standard thermocouples :

  • Type K (Chromel-Alumel ANSI standard)
  • Temperature range from-200 to 1200°C
  • Cladding Inconel 600 diameter 1,5 mm
  • Insulation Mg O
  • Hot Joint Insulated
  • T.C. length On request

Thermocouples are available in 2 configurations :

  • High Vacuum brazed on all types of flanges and transitions (KF, CF, VCR, etc.)
  • High Vacuum brazed on electrical feedthrounghs and then joined with flanges (KF, CF, VCR, etc.)by vacuum brazing or TIG welding. In these version the thermocouple cladding is ground isolated. The thermocouple, therefore, can be utilized directly on objects under voltage.

Air-side connections are available in three versions :

  • Mating compensated miniature style connectors (up to 200°C)
  • Extension wire junction of the compensated cable
  • Mating compensated miniature style connectors (up to 650°C) with ceramic standard size connectors. On request other connectors me be supplied

The following thermocouples series are available :

  • TCSK with miniature style connector 200°C or 500°C vacuum brazed on KF, CF vacuum flange or others transitions (VCS etc.). More then one thermocouple can be brazed on each vacuum flange.
  • TCCK vacuum brazed on KF, CF vacuum flange or others transitions (VCS etc.) with extension wire junction of the compensated cable. More than one thermocouple can be brazed on each vacuum flange.
  • TPSK the same as TCSK type with electrical feedthroughs to insulate Inconel sheath.
  • TPCK the same as TCCK type with electrical feedthroughs to insulate Inconel sheath.
  • TXSK and TXCK a wide choice of combinations of thermocouples and power feedthrounghs on the same vacuum flange.

The catalogue presents also multi - type feedthrounghs, including both thermocouple and power feedthrounghs. Several combinations provide flexibility to reduce the number of penetrations into the sealed zone.

The thermocouples are included in a seamless metallic sheath (standard material Inconel 600). The two conductors are insulated by means of a MgO powder highly compacted. The hot joint configuration is shown in figure C-1.

Thermocouples are also greatly flexible allowing an easier forming for adaptation to the chamber layout.

5) Special components

VLT can supply a wide range of special components vacuum brazed for almost any field of application as Research, Aerospace, Electrical, Thermal, Mechanical etc.

As an example VLT show components and system for Synchrotron.