Spectroscopic determination of the time dependent magnetic field distribution in pulsed-power plasmas

Summary form only given. Observation of the magnetic field distribution in short-duration plasmas is of major importance since it allows for investigating the field penetration mechanisms and for determining the energy dissipation in the plasma. The current density obtained allows the electron drift velocity to be known, using independent measurement of the electron density. In the case of field diffusion, the penetration depth gives the plasma conductivity yielding the plasma Ohmic heating. Here, we report on the determination of the magnetic field distribution in a coaxial Plasma Opening Switch (POS) and a gas-puffed Z-pinch plasma using two methods: 1) Observation of the Zeeman splitting of emission lines where emissions with two different polarizations were observed in a single discharge in order to discriminate the Zeeman splitting against the inevitable Doppler line broadening of ions moving under the field gradients. 2) Observation of the ion acceleration due to the field gradients from the line Doppler shifts. Together with the electron density determined from particle ionization times and Stark broadening, this yields the magnetic field gradient. For these methods, lines from heavy ions (such as Ba II) and light ions (Li II, C II-C V, Mg II, Ca II), respectively, were used in order to minimize or maximize the Doppler contribution to the line profiles.