Creation of a homogeneous plasma column by means of hohlraum radiation for ion-stopping measurements

TL;DR

This study uses radiation-hydrodynamics simulations to create a stable, homogeneously ionized carbon plasma via hohlraum radiation for precise ion-stopping measurements, highlighting the importance of controlling shock wave effects.

Contribution

It demonstrates a method to produce a stable, homogeneous plasma suitable for ion-stopping experiments using hohlraum radiation and analyzes the impact of shock waves on plasma stability.

Findings

Stable ionization degree of carbon (~3.75) maintained for measurement duration

Carbon column density remains within ±7% variation

Shock wave effects can significantly distort ion measurements if not managed

Abstract

In this work, we present the results of two-dimensional radiation-hydrodynamics simulations of a hohlraum target whose outgoing radiation is used to produce a homogeneously ionized carbon plasma for ion-beam stopping measurements. The cylindrical hohlraum with gold walls is heated by a frequency-doubled ($\lambda_l = 526.5$ $\mu m$) $1.4$ $ns$ long laser pulse with the total energy of $E_l = 180$ $J$. At the laser spot, the peak matter and radiation temperatures of, respectively, $T \approx 380$ $eV$ and $T_r \approx 120$ $eV$ are observed. X-rays from the hohlraum heat the attached carbon foam with a mean density of $\rho_C = 2$ $mg/cm^3$ to a temperature of $T \approx 25$ $eV$. The simulation shows that the carbon ionization degree ($Z \approx 3.75$) and its column density stay relatively stable (within variations of about $\pm7\%$) long enough to conduct the ion-stopping measurements. Also, it is found that a special attention should be paid to the shock wave, emerging from the X-ray heated copper support plate, which at later times may significantly distort the carbon column density traversed by the fast ions.