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.

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

Coaxial cable extensions & connectors

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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 Mmineral insulated cable extensions are terminated by two HN-connectors (plugs or jacksmale or female). For pulse and current transmissions, the coaxial cables are 6 mm in diameter adapted to 50 Ω characteristic impedance with high-immunity to electromagnetic parasitesparasitic signals. 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.

  • 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 our expertise in the design and manufacture of nuclear instruments to solve customer challenges.

Examples of customization of standard parts

  • Adapted electrical characteristics (characteristic impedance, capacitance, line resistance, attenuation, transfer impedance).

  • Cable insulator material (Al2O3, MgO, SiO2).

  • LOCA (Loss 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