Investigating the energy loss of ions in plasma is a long standing research topic of the plasma physics group at GSI. In particular at low particle velocity, which corresponds to the maximum of the stopping power, the theoretical descriptions based on perturbative approaches fail and models show a discrepancy. This lack of understanding is particularly critical and could be a reason for the issues met with ignition at NIF. One reason therefore could be that the alpha-heating was overestimated due to disregard of coupling effects in the compressed plasma leading to lower stopping powers.
In the parameter region accessible at GSI, the known perturbative stopping-power models are expected to be inaccurate due to the strong beam-plasma coupling. Significant discrepancies have been reported between the different theoretical approaches, reaching 30% in our configuration.
First experiments using ions from the GSI UNILAC accelerator with a pulse length of 5-7 ns to probe a laser generated fully ionized carbon plasma showed energy-loss values significantly smaller than predicted by 1st order perturbation theory. To improve the quality of these measurements shorter ion pulses would be preferable. Therefore, we intend to perform energy loss measurements with laser accelerated ions, shaped with the LIGHT (Laser Ion Generation, Handling and Transport) beam line set up at GSI.
The talk will cover the efforts to create mono-energetic ($\Delta$E < 5%) laser accelerated C-ion pulses with a pulse length of below 1.5 ns for probing a laser generated plasma 6 m away from the TNSA target.
|Working group||Laser-driven ion acceleration|