Coaxial cable extensions & connectors

Coaxial cable extensions & connectors

In severe operating conditions, and when the use of detectors with an integral cable is not preferred, an alternative is to use a coaxial mineral insulated cable extension connected to the detector.

High level of resistance or radiations and electromagnetic parasitic signals
Watertight, mineral insulated cables and connectors
Customization according to the user’s needs
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Technical information

Basic type MI Cable External diameter (mm) Signal transmission Connector type
EXT-HN 6 Pulse, fluctuation (Campbell) and current modes HN
EXT-BNC 3 Current BNC


Such mineral insulated cable extensions are terminated by two HN-connectors (plugs or jacks). For pulse and current transmissions, the coaxial cables are 6 mm in diameter adapted to 50 Ω characteristic impedance with high-immunity to parasites. For direct current transmissions, a 3 mm diameter cable extension is available.

Custom coaxial cable extensions & connectors

By full control of the following processes, Photonis Nuclear Instrumentation can supply custom coaxial cable extensions & connectors with the highest quality and reliability levels

  • Adaptation of industrialized coaxial cable extensions & connectors to customer specific requirements.
  • Development of new coaxial cable extensions & connectors with our experienced R&D team.
  • Long term collaboration with the French Alternative Energies and Atomic Energy Commission  / CEA (theoretical approach, modeling, qualification tests in research reactors).
  • Complete manufacturing process on site. 
  • Support from all the Photonis Group activities, experience and knowledge.
  • Certifications & Quality Assurance programs adapted to the customer environment.
  • Technical support, applying expertise.

Examples of custom versions from basic types

  • Adapted mechanical interface with the equipment (Customized external dimensions, cable curvature radius)
  • Adapted electrical characteristics (characteristic impedance, capacitance, line resistance, attenuation, transfer impedance)
  • Cable insulator material (Al2O3, MgO, SiO2)
  • LOCA (Lose Of Coolant Accident) and post-LOCA protection ?
  • Ruggedized structure for harsh environment (radiation, temperature, humidity, mechanical stress)
  • Coaxial Mineral insulated connector type (HN, BNC, BNC HT or specific). Reinforced types are available for high pressure, high temperature conditions
  • External mechanical and/or electrical protection around the cable and/or the connectors (folded spiral seam, radiation resistant heat-shrink sleeve)
  • Connectors can also be delivered in mating connector or tight feedthrough versions

Main features

  • Structure configuration: Coaxial (one central conductor, one external envelope).
  • Cable materials: Multi metallic cable envelope for high immunity to parasites. Magnesia (MgO) cable insulator
  • Connector Material: Stainless steel and Nickel structure and high-grade Alumina (Al2O3) insulator.



The French Atomic Energy Commission (CEA) selected Photonis as its technological partner for a co-operative development of neutron and gamma detectors when the French nuclear power program took shape in the sixties.

Our references

PWR – Safety critical signal transmission in reactor building – Mineral insulated cable extension – EXT-HN - France




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