TIME FIDUCIAL AT THE LIL FACILITY AT CEA/CESTA

摘要

The CEA is currently developing the "Laser Mega Joule "(LMJ), a facility capable of concentrating an extremely high quantity of energy from 240 laser beams on a micro target for a brief moment. The characteristics of the facility have been defined to obtain the temperature and pressure conditions required to reach thermonuclear combustion. The "Ligne d'Integration Laser" (LIL) is a facility designed to validate the choices adopted for the LMJ. It consists of a basic laser line from the MJL with four identical beams. On the LIL, an experiment consists of a series of laser/material interaction firings. For a given firing, there is a concatenation of the phenomena from the triggering of the physical mechanisms to the recording of the signals on the recording instruments (diagnostics). The interaction gives rise to plasma One sure method to enable the reconstruction of the events in the course of the experiments involves recording an optic time fiducial signal on the main instruments. This temporary marking makes it possible to reposition in time the signals recorded on the measuring instruments against a point of reference. We present here a prototype that has been developed for the time fiducial of the visible streak cameras : "SYMOD : SYsteme de Marquage Optique par Diode laser". The original architecture of the bench is based on the use of one laser diode per diagnosis to be marked. Other components, including synchronization equipment and two chronometry arrays, are arranged around this source which constitutes the main component of the device. Tests have been run to validate the technical choice of the source and to demonstrate that the main time requirements concerning the fiducial are met (rise time ＜ 50ps and time jitter ＜ 16ps rms).