91̽»¨

Abstract:

Inspired by the 2022 edition of an epitaph dedicated to a soldier of the fourth cohors Cypria died in Sinope, the author offers an update on the epigraphic evidence concerning auxiliary cohortes and alae from the province of Pontus and Bithynia. Since it was an unarmed province, the presence of these soldiers, as well as of legionaries, must be considered only temporary and connected to the passage of Roman troops towards the eastern border of the Empire. It is worth considering, in this regard, that most of the inscriptions date to the 2nd or 3rd century. Only those relating to the soldiers of the cohors Cypria seem to be earlier, but they could be connected with the expedition against Mithridates king of the Bosphorus in the time of Claudius or with the momentary annexation of the Bos-phoran kingdom under Nero.

Abstract:

Autoresonant phase locking of the plasma wakefield to the beat frequency of two driving lasers offers advantages over conventional wakefield acceleration methods, since it requires less demanding laser parameters and is robust to variations in the target plasma density. Here, we investigate the kinetic and nonlinear processes that come into play during autoresonant plasma beat-wave acceleration of electrons, their impact on the field amplitude of the accelerating structure, and on acceleration efficiency. Particle-in-cell simulations show that the process depends on the plasma density in a nontrivial way but can be reliably modeled under specific conditions. Beside recovering previous fluid results in the deeply underdense plasma limit, we demonstrate that robust field excitation can be achieved within a fully kinetic self-consistent modeling. By adjusting the laser properties, we can amplify the electric field to the desired level, up to wave breaking, and efficiently accelerate particles; we provide suggestions for optimized laser and plasma parameters. This versatile and efficient acceleration scheme, producing electrons from tens to hundreds of MeV energies, holds promise for a wide range of applications in research industry and medicine.