# Presentation: 532324

## Plasma and Warm Dense Matter Studies

**Richard W. Lee, ***Lawrence Livermore National Laboratory*
**P. Audebert, ***Laboratoire pour l’Utilisation des Lasers Intenses, *
*	**École Polytechnique Palaiseau, France*
**R.C. Cauble, ***Lawrence Livermore National Laboratory*
**J.-C. Gauthier, ***Laboratoire pour l’Utilisation des Lasers Intenses, *
*	**École Polytechnique Palaiseau, France*
**O.L. Landen, ***Lawrence Livermore National Laboratory*
**C. Lewis, ***School of Mathematics and Physics, Queen’s University, Belfast, *
*	**Northern Ireland*
**A. Ng, ***Department of Physics and Astronomy, University of British Columbia, Canada*
**D. Riley, ***School of Mathematics and Physics, Queen’s University, Belfast, *
*	**Northern Ireland*
**S.J. Rose, ***Central Laser Facility, Rutherford Laboratory, Chilton, Oxfordshire, UK*
**J.S. Wark, ***Department of Physics, Clarendon Laboratory, Oxford University, *
*	**Oxford, UK*

## The Importance of these States of Matter Derives from 

***The Importance of these States of Matter Derives from ***
***  ******their Wide Occurrence***

**Hot Dense Matter (HDM) occurs in: **

**Supernova, stellar interiors, accretion disks**
**Plasma devices: laser produced plasmas, Z-pinches**
**Directly driven inertial fusion plasma**

**Warm Dense Matter (WDM) **
**	****occurs in: **

**Cores of large planets **
**Systems that start solid and end as a plasma**
**X-ray driven inertial fusion implosion**

## Creating WDM

**Generate ≤10 eV solid density matter**
**Measure the fundamental nature of the matter via equation of state**

**Probing resonances in HDM**
**Measure kinetics process, redistribution rates, kinetic models**

**Probing dense matter**
**Perform, *****e.g*****., scattering from solid density matter**
**Measure n****e****, T****e****, <Z>, *****f*****(v), and damping rates**

***Highlight of Three Experimental Areas in the High-Density ***
***   ******Finite-temperature Regime***

## LCLS, Uniquely, Can Both Create and Probe High-density

***   ******Finite-temperature Matter***

**To create WDM requires rapid uniform bulk heating**
**High photon numbers, high photon energy, and short pulse length => high peak brightness**
**To pump/probe HDM requires an impulsive source of high energy photons**
**Pump rate must be larger than competing rates**
**No**** laser source has flux (laboratory x-ray lasers or otherwise)**
**To measure plasma-like properties requires short pulses with **
**   ****signal > plasma emission**
**No existing source can probe HDM or create WDM to probe**
***	******• ******10******10****** increase in peak brightness allows access to novel regimes***

## Theoretically the Difficulty with WDM is There are No Small 

***   ******Parameters***

**WDM is the regime where neither condensed matter (T = 0) methods nor plasma theoretical methods are valid**
**The equation of state (EOS) of Cu indicates the problems**

**Thermodynamically consistent EOS based on numerous schemes has proved impossible (attempted from 70’s)**
**A single incomplete description is now employed (from 1988)**

## In the WDM Regime Information Leads to New Results –

***   ******LCLS Will Be Unique Source of Data***

**Experimental data on D****2**** along the Hugoniot shows theories were and are deficient**
**LCLS can heat matter rapidly and uniformly to generate isochores**

- EOS’s along o Al isochore

- Al -T phase diagram

## Experiment 1: Using the LCLS to Create WDM

**For a 10x10x100 μm sample of Al**
**Ensure the sample uniformly heated use 33% of beam energy**
**Equating absorbed energy to total kinetic and ionization energy**

**Generate a 10 eV solid density with n****e**** = 2x10****22**** cm****-3**** and <Z> ~0.3**
**State of material on release can be measured with a short pulse laser**
**Estimated to be C****s**** ~ 1.6x10****6**** cm/s with pressure 4 Mb**
**For 500 fs get surface movement by 80 Å**
**Material rapidly and uniformly heated releases isentropically**

## Experiment 2: LCLS Can Excite a Line Transition in HDM and 

***   ******Provide Observable Results***

**For HDM the plasma collision rates and spontaneous decay rates are large**
**To effectively move population, pump rate, R, must be > decay rate, A => R ********A**
**For ****I ****= 10****14**** W/cm****2**** R/A ~ 10****-4****g****U**** /g****L********4**
**For LCLS**
******~ 10 Å         R/A ~ 1**
**For laboratory x-ray lasers**
******> 100 Å         R/A << 1**

## LCLS Will Create Excitation Levels That Are Observable in Emission

**Schematic experiment**

**Simulations**

**• ****t = 100 ps LCLS irradiates plasma**

- CH

- Al

- LCLS tuned to 1869 eV

- Observe emission with
-  x-ray streak camera

**• ****t = 0 laser irradiates Al dot**

## Experiment 3: LCLS Will Measure Properties of Solid Density

***   ******Finite Temperature Matter***

**Scattering from free electrons provides a measure of the T****e****, n****e****, *****f*****(v), and plasma damping**
**structure alone not sufficient for plasma-like matter**
**Due to absorption, refraction and reflection visible lasers can not probe high density**
**no high density data**
**LCLS scattering signals will be well above noise for both WDM and HDM**

- Scattering and absorption from solid Al

## Scattering of LCLS Will Provide Data on Free, Tightly-, and 

***   ******Weakly-bound Electrons***

**Weakly-bound and tightly-bound electrons depend on their binding energy relative to the Compton energy shift**
**Those with binding energies less than the Compton shift are categorized weakly boun****d.**

**For a 25 eV, 4x10****23**** cm****-3**** plasma the LCLS produces10****4**** photons from the free electron scattering**

## EOS measurements illuminate the microscopic understanding of matter

***   ******Plasma-like Properties***

**EOS measurements illuminate the microscopic understanding of matter**
**The state of ionization is extremely complex when the plasma is correlated with the ionic structure**
**Other properties of the system depend on the same theoretical formulations**
**For example, conductivity and opacity**

## Since the advent of HDM laboratory plasma quantitative data has been scarce

***   ******Shapes, and Plasma Formation***

**Since the advent of HDM laboratory plasma quantitative data has been scarce**
**The rapid evolution of high T****e**** and n****e**** matter requires a short duration, high intensity, and high energy probe => LCLS**
**The LCLS will permit measurements of:**
**Kinetics behavior ****–**** rates, model construction**
**Plasma coupling ****–**** direct measurement of S(k, ********)**
**Line transition formation ****–**** line shapes, shifts, ionization depression**
**HED plasma formation ****–**** measure matter in the densest regions**