ALCEN's activities in
Inertial confinement

Through its experience gained in the frame of the French MegaJoule Laser programme, ALCEN has developed an unique expertise in technologies dedicated to laser driven inertial confinement fusion devices: design, manufacturing and assembly of mechanical, opto-mechanical and pulsed high voltage sub-assemblies, specific optical coatings, integration and maintenance services.

Control command

Supervision and synchronization of all sub-systems of a laser driven inertial confinement fusion facility require powerful and efficient control command systems. Several hundreds of thousands signals are thus commonly generated and exchanged to insure safe and optimized behavior of the machine.

The control command system is as well used to control plasma operation and collect the huge amount of data that will be afterwards analyzed by the scientists.

ALCEN's expertise

Through the CHAMPALLE subsidiary, ALCEN designs, develops and manufactures control systems for extreme environments: explosive environments, extreme temperatures, offshore systems, nuclear power plants…

With in-house testing capability, CHAMPALLE can provide control command cabinets, desks or boxes of the highest safety standards and quality. Developments are carried out using V-models and engineered for all types of PLC. 

The RCCM-E standards are specifically applied in the nuclear domain.

ALCEN's subsidiaries for Control command

ALCEN's references

Control systems for cryogenic gas transfer

High safety level control systems

Nuclear machinery control systems

Process and control room for electrical power solar plant


To create the conditions of fusion inside the target, the tritium-deuterium mix must be kept in solid state. This is achieved at temperatures in the range of 20K. Specific cryogenic equipment are thus required to assemble, transport, precisely position and hold the target prior to its illumination by the laser beams.

In the frame of their activities in the scientific and energy domains, some ALCEN subsidiaries have developed dedicated knowledge in the cryogenic technology that could apply to the design and manufacture of specific sub-assemblies.

ALCEN's expertise

  • Design and integration of cryogenic systems
  • Cryostats
  • Valves and motorized connection systems for liquid and gas transfer
  • thermofluidics and thermomechanics design

ALCEN's subsidiaries for Cryogenics

ALCEN's references

4K cryostat for the characterization of cryogenic targets

Manufacture of the ITER pre-production cryogenic pump

Assembly of XFEL Cryomodules

Valves and motorized connection systems for cryogenic gas transfer


Among parameters commonly mesured during operation, one can quote:

  • The laser energy dissipated in the target
  • The target temperature
  • The pressure 
  • Speed and symmetry of the implosion
  • Density and temperature of the fuel mix
  • Generated energy

The very short duration of the reaction requires ultra-fast detectors. In addition, for those located inside the experimental chamber, they have to resist to the harsh environment: X-ray and neutron radiations, shock wave, electromagnetic disturbances.

Several families of diagnostics are implmented in inertial confinement fusion reactors, such as optical, X-Ray and nuclear diagnostics.

Design, manufacturing and integration of these complex sub-assemblies require specific technological know-how in fields mastered by ALCEN.

ALCEN's expertise

  • Assembly in clean environment
  • Electromagnetism
  • High precision machining
  • Optics and opto-mechanics
  • Radioactive environment
  • Thermal management
  • Vacuum engineering
  • X-ray components and devices

ALCEN's subsidiaries for Diagnostics

ALCEN's references

Design, manufacture and on-site installation of plasma diagnostics for the LMJ demonstrator

X-Ray imaging system prototype

Apollo system for surveillance in nuclear environment

Design and manufacturing of X-Ray components

Experimental chamber

The experimental chamber consists in a several meter diameter vacuum chamber of spherical shape. Made out of materials compatible with the severe constraints of the fusion reaction in terms of temperature, pressure and radiations, it hosts the target and is equipped with ports where laser beam systems and diagnostics are plugged.

ALCEN's expertise

  • Assembly in clean environment
  • High precision machining
  • Radioactive environment
  • Vacuum engineering

ALCEN's subsidiaries for Experimental chamber

ALCEN's references

Manufacturing of the LMJ protection panels

Frequency conversion

Before being injected into the experimental chamber and interacting with the target, each laser beam goes through a dedicated optical subassembly where:

  • Its frequency is converted from a value suitable for amplification purposes to an optimized value in terms of interaction with the target; 
  • It is focused to a few mm diameter.

The design, manufacture and integration of frequency and focusing systems benefits from the expertise developed by ALCEN in laser amplification and beam transport sections.

ALCEN's expertise

  • Assembly in clean environment
  • High precision machining
  • Mechanical and opto-mechanical design

ALCEN's subsidiaries for Frequency conversion

ALCEN's references

Manufacturing of opto-mechanical sub-assemblies of the LMJ Focusing and Frequency Conversion System

Hot cells

Even if the fusion reaction does not produce radioactive products, components of the experimental chamber may be activated by high energy neutrons and tritium.

Hot cells are thus required to insure maintenance, decommissioning, and detritiation, of the exposed sub-assemblies, using remote handling operations. 

ALCEN's expertise

In the frame of its activities in the nuclear domain, Alcen has developed a recognized expertize in design and manufacturing of hot cell key parts (remote handling and robotic systems, glove boxes…) as well as in the supply of turnkey hot cells.

ALCEN's subsidiaries for Hot cells

ALCEN's references

Design and Manufacturing of LMJ Glove boxes

Hotcell for an electromechanical press

Nuclear fuel rod cutting bench

Design and Engineering of the Astrid hot cell

Laser amplification

The original laser pulse generated by the pilot must be strongly amplified (factor of several tens of thousands) to reach energy required for the fusion experiments. This is achieved inside the amplification chain, a complex assembly of optical, high voltage and mechanical components: doped laser glass slabs, flash lamps converting electrical energy generated by capacitors into light to pump the laser glasses, optical components allowing for shaping, propagating and focusing the laser beam.

To maximize amplification while limiting size of the halls, the laser usually travels several times through the several tens of meters long chain. This requires very precise machining and positioning of the various sub-assemblies, in addition operating under severe cleanliness environment due to the high energy of the laser.

Up to a few hundreds of laser beams are commonly amplified in laser driven inertial confinement fusion facilities.

For several tens of years, ALCEN has been developing key technologies implemented in laser amplification chains and is today one of the CEA major partners on the LMJ laser chain.

ALCEN's expertise

  • Assembly in clean environment
  • High precision machining
  • High pulsed power
  • Mechanical and opto-mechanical design
  • Vacuum engineering

ALCEN's subsidiaries for Laser amplification

ALCEN's references

Design, Manufacturing, Assembly and On-site installation of the LMJ SAHA

Design, Manufacturing, Assembly and On-site installation of the PETAL amplification chain

Manufacturing of the LMJ amplifier mechanical structures

Manufacturing of the LMJ M1 deformable mirror

Design and Manufacturing of the LMJ Capacitor Bank Module

Laser transport

Once amplified, the laser beams must be transferred to the experimental chamber. This is achieved through a chain of successive mirrors operating in a clean environment. The beams, entering the transport section with parallel axis of propagation, are focused and finally spatially distributed all around the experimental chamber. 

The expertise developed by ALCEN ensures the Group designs, manufactures and installs complete beam transport lines on-site for the most demanding laser and inertial confinement fusion facilities. 

ALCEN's expertise

  • Assembly in clean environment
  • High precision machining
  • Mechanical and opto-mechanical design

ALCEN's subsidiaries for Laser transport

ALCEN's references

Design, Manufacturing, Assembly and On-site installation of the LMJ Transport section

Vacuum systems

To enable propagation of the highly focused laser beams and proper interaction, the target is placed at the centre of a large diameter empty/clear? vessel (the experimental chamber). Furthermore, due to very high power densities, some subassemblies of the amplification sections also operate at a pressure in the range of 10-2 Pa. 

Depending on the required operating pressure, various pumping techniques are thus implemented in laser-driven inertial confinement devices: mechanical, ion or cryogenic pumps.

Through its research activities , Alcen has been developing expertise in vacuum technology including design, engineering, material compatibility and preparation, system manufacturing and integration, leak test and commissioning

ALCEN's subsidiaries for Vacuum systems

ALCEN's references

Design, Manufacture and Assembly of LMJ amplifying sections

Manufacture of the ITER pre-production cryogenic pump

Vacuum chamber for ITER PF coil conductor tests

Vacuum chambers and mechanics for mirrors on soft and hard X-ray Synchrotron beamlines

Assembly & Operation

On top of the various and complementary skills developed by ALCEN for the design and manufacturing of high power laser components and subassemblies, and its proven track record through significant achievements on major programs, the Group has as well as developed a recognized expertise in works and services related to assembly, operation and maintenance of complex facilities.

Fostering on its large technological background and its long experience in operation of industrial premises and management of long term programs, ALCEN has the capability to deploy on customer sites dedicated teams and means to conduct assembly works, operate and maintain special facilities, especially under harsh environment.

Operations are performed following specific constraints in relation to Environment, Health and Safety imposed by the customer.

ALCEN's subsidiaries for Assembly & Operation

ALCEN's references

On-site integration of LMJ laser amplification sections

Operation of the Sol Gel Coating facility for LMJ optical components

Maintenance of the LMJ demonstrator

Assembly of the XFEL Cryomodules