Experimental Observation of Proton Bunch Modulation in a Plasma at Varying Plasma Densities

We give direct experimental evidence for the observation of the full transverse self-modulation of a long, relativistic proton bunch propagating through a dense plasma. The bunch exits the plasma with a periodic density modulation resulting from radial wakefield effects. We show that the modulation is seeded by a relativistic ionization front created using an intense laser pulse copropagating with the proton bunch. The modulation extends over the length of the proton bunch following the seed point. By varying the plasma density over one order of magnitude, we show that the modulation frequency scales with the expected dependence on the plasma density, i.e., it is equal to the plasma frequency, as expected from theory

Sestak's proposal of term "tempericity" for non-equilibrium temperature and modified Tykodi's thermal science classification with regard to methods of thermal analysis

Rovnovážná (termodynamická) teplota tělesa je definována nultým zákonem termodynamiky jako veličina získaná teploměrem za teplotní rovnováhy mezi tělesem a teploměrem. Termín teplota je ale používán i jako popis okamžitého teplotního stavu během procesů, kde není dosaženo teplotní rovnováhy. Tykodiho návrh na rozdělení věd o teple na tři oblasti byl pozměněn k vyjádření závislosti teploty na čase a místě uvnitř systému. Tyto tři oblasti byly nazvány termostatikou (rovnovážná termodynamika), termostedikou (termodynamika stavů = stacionární stavy) a termokinetika (věda o teple zabývající se nestabilními - nestacionárními stavy). Rovnovážná teplota je využívána pouze termostatikou. Pro ostatní oblasti, kde je uplatněn Newtonův zákon chlazení a/nebo jakýkoliv ze dvou Fourierových zákonů, není možné použít rovnovážnou teplotu vycházející z nultého zákona. Termická analýza, která studuje nestabilní stavy (teplota je funkcí času t a prostorové souřadnice x), by měla být podoblastí termokinetiky a s ní související modely kinetiky by měly zahrnovat místní změny teploty vyvolané samo-ochlazením a samo-ohřevem procesy probíhajícími uvnitř vzorku.The equilibrium (thermodynamic) temperature of a body is defined by zeroth law of thermodynamics as a quantity obtained by thermometer as a result of thermal equilibrium between the body and the thermometer. However, the term temperature is also used for description of any instantaneous thermal state during processes where no thermal equilibrium is reached. The proposal of Tykodi to divide thermal science into three branches has been modified to express the dependence of temperature on time and position inside a system. The three branches have been called thermostatics (equilibrium thermodynamics), thermostatics (thermodynamics of steady = stationary states) and thermokinetics (thermal science dealing with unsteady—non-stationary states). Equilibrium temperature is used only at thermostatics. For other branches of thermal science where the Newton cooling law and/or any of both Fourier laws are applied, no equilibrium temperature with respect to zeroth law is expected. Thermal analysis studying unsteady states (temperature is a function of time t as well as of space coordinates x) should be subject of thermokinetics, and the appropriate kinetic models should include the local temperature changes evoked by selfcooling or self-heating due to process running inside sample

Are nonisothermal kinetics fearing historical Newton's cooling law, or are just afraid of inbuilt complications due to undesirable thermal inertia?

Relations between the magnitude of the change of the ratios of crystallization and melting temperature with glass transition temperature, that is Tc/Tg and Tm/Tg, determine the order of the values of relative change of glass stability (GS) parameters dKH/KH, dKW/KW and dKLL/KLL. The linear correlation of new GS parameters FK and FKA which include fragility and reduced glass transition temperature with logRc is a better correlation of KLL. The stretching exponent increases as a linear function of T/Tg in the interval 1≤T/Tg<1•1 for given values of the dynamic fragility parameter m. As result, it follows that the kinetic term in fragility can be neglected. The thermodynamic term, which has a dominant role in fragility can be determined by the expressions for configurational entropy and configurational heat capacity. We compared Sc(T) a function of temperature dependence of configurational entropy which was obtained by Sipp et al and ScVFT (T) a function proposed by Yue. Both Sc(T) and ScVFT (T) have the same temperature dependence and almost overlap. Therefore, using either Sc(T) or ScVFT (T) we will get the same value of fragility index. From the dependence of lnSc(T) versus lnT it is possible to successfully predict the relations between the values of m for different glass formers

Proton-driven plasma wakefield acceleration in AWAKE.

In this article, we briefly summarize the experiments performed during the first run of the Advanced Wakefield Experiment, AWAKE, at CERN (European Organization for Nuclear Research). The final goal of AWAKE Run 1 (2013-2018) was to demonstrate that 10-20 MeV electrons can be accelerated to GeV energies in a plasma wakefield driven by a highly relativistic self-modulated proton bunch. We describe the experiment, outline the measurement concept and present first results. Last, we outline our plans for the future. This article is part of the Theo Murphy meeting issue 'Directions in particle beam-driven plasma wakefield acceleration'