Patent Number: 
Section: claims

1. A characterisation system comprising:a characterisation cell for smoke analysis by optical spectrometry, comprising:a reaction chamber;an inlet orifice for the inlet of smoke into the reaction chamber;an outlet orifice for the evacuation of smoke from the reaction chamber;an analysis window for entry of a laser beam intended to form the plasma inside the reaction chamber;a fan for ensuring scanning of inert gas in the vicinity of the analysis window; anda shielding injector coaxially aligned with the inlet orifice configured to coaxially inject smoke shielded by a jet of inert gas around the smoke into the reaction chamber;a collector downstream of the outlet orifice of the cell configured to recover the smoke after its analysis;a pressure regulator for keeping the pressure constant in the reaction chamber of the cell,wherein the pressure regulator comprises a regulation valve placed downstream of the collector to compensate for a loss of charge due to clogging of filters of the collector,wherein the regulation valve is connected to a pressure probe placed in the cell for measuring the pressure therein for its servo-control, andwherein the regulation valve is servo-controlled as a function of the pressure measured inside the cell and which is adapted to open progressively as the collector gets clogged;a reactor for the generation of smoke;a second collector positioned downstream of the reactor;a second regulation valve for regulating the pressure inside the reactor;wherein the second regulation valve is placed downstream of the second collector,wherein the second regulation valve is connected to a second pressure probe placed in the reactor for measuring the pressure therein for its servo-control, andwherein the second regulation valve is servo-controlled as a function of the pressure measured inside the reactor and which is adapted to open progressively as the second collector gets clogged. 2. The system of claim 1, wherein the cell further comprises an arm extending between the reaction chamber and the analysis window, the arm being formed in two parts of different cross-sections, the larger cross-section part being arranged nearer the analysis window and the smaller cross-section part being arranged nearer the reaction chamber to form a Venturi and to ensure overpressure nearer the window. 3. The system of claim 1, wherein the flow rate of inert gas generated by the fan is adjustable. 4. The system of claim 1, wherein the flow rate of inert gas generated by the coaxial shielding injector is adjustable. 5. The system of claim 1, wherein the injector is a circular double nozzle having first and second coaxial orifices, the first orifice having a disc-shaped cross-section for the inlet of smoke, and the second orifice having a ring-shaped cross-section which encloses the first orifice for the inlet of inert gas. 6. The system of claim 1, wherein the cell further comprises a viewing window for observation of the plasma produced inside the reaction chamber during its operation. 7. The system of claim 1, wherein the fan also ensures scanning of inert gas in the vicinity of the viewing window. 8. The system of claim 1, wherein the flow rate of inert gas generated by the Venturi is adjustable. 9. The system of claim 1, wherein the cell further comprises an arm extending between the reaction chamber and the inlet orifice. 10. The system of claim 1, wherein the cell further comprises an arm extending between the reaction chamber and the outlet orifice. 11. The system of claim 1, wherein the cell further comprises a first arm extending between the reaction chamber and the inlet orifice, a second arm extending between the reaction chamber and the outlet orifice, and a third arm extending between the reaction chamber and the analysis window. 12. The system of claim 11, wherein the first and second arms extend along a first axis, and the third arm extends along a second axis that is perpendicular to the first axis. 13. The system of claim 11, wherein the third arm is formed in two parts of different cross-sections, the larger cross-section part being arranged nearer the analysis window and the smaller cross-section part being arranged nearer the reaction chamber to form a Venturi and to ensure overpressure nearer the window. 14. The system of claim 1, wherein the smoke is a smoke of nanoparticles. 15. The system of claim 1, wherein the second regulation valve regulates the pressure inside the reactor so as to keep said pressure constant. 16. The system of claim 1, wherein the second regulation valve is placed at the outlet of the second collector. 17. The system of claim 1, wherein the second regulation valve is adapted to open progressively as filters of the second collector gets clogged due to nanoparticles. 18. The system of claim 1, wherein an outlet of the reactor is connected to a pump which creates a flow of smoke.