WORK PACKAGE ENABLING RESEARCH 2015 scientific/technical report Deadline: 31 December 2015

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1 WORK PACKAGE ENABLING RESEARCH 2015 scientific/technical report Deadline: 31 December 2015 Project title (as in Task Agreement) Principal Investigator Beneficiary of Principal Investigator Project reference number (as in Task Agreement) Towards demonstration of Inertial Fusion for Energy S. Jacquemot CEA AWP15 ENR 01/CEA 02 Filename should be of the format: WPENR_AWP15_interim_report_Beneficiary nn where Beneficiary nn is, for example, ENEA 01. Purpose and use of report This compact report is to report the progress on the deliverables, to justify payment. A brief summary of the scientific highlights is also requested. While the report will be available to STAC the performance will be assessed by the PMU unless there are issues which require the advice of STAC. The mid term evaluation of the project, where relevant, is a separate activity but can refer to these reports. It will also be uploaded to the Enabling Research Wiki pages fusion.org/erwiki/index.php?title=main_page), and thereby be available to the PMU and the relevant Work Package and Task Force Leaders. The reports should be as brief and clear as possible, referring to publications and other information for details. However there should be enough information to support statements that deliverables have been achieved. As an indication the full report should not exceed 4 pages excluding this title page. Please keep to the report format and do not attach additional information. If there are one or two particularly significant figures that are needed to demonstrate the results, these can be included in the tables. WPENR_AWP15_interim_report_CEA 02 1

2 1. Main scientific output summary The following section gives some highlights obtained in 2015 by the ToIFE partners. The selection, done by the coordinator, may be biased but it reflects the variety of the activities towards the objective of the project: achieving the fundamental understanding required to demonstrate the viability of laser driven fusion as an alternative road towards sustainable, clean and secure energy source. More achievements are given in the following section and on the project s website: KiT/ToIFE.htm. Mission 1. Acquiring new insights into the basics of ignition physics Plasma atomic physics & radiation sources Determining the radiative properties of mid Z elements used as ablator dopants in ICF targets is one of the tasks allocated to the project s partners. Influence of hot electrons on x ray emissivities was investigated by IST at LCLS while LIDyL focused on analysis of LULI2000 near LTE 2p 3d absorption structures, validating SCO RCG hybrid computations [8], and of density effects, in collaboration with LANL [3], evidencing shifts of the binding energy of the H and He like ground states. Laser Plasma Interaction Crossed beam energy transfer (CBET) was investigated by CPhT and CELIA for optically smoothed beams [5,6]. It was evidenced that the speckle structure of the beams has in general a minor influence on the energy transfer. The PGCO approach (see task 2.2) has been benchmarked as an efficient method to compute CBET when implemented into rad hydro codes for realistic simulations of laser fusion experiments. Combustion A general relation, connecting burning plasma regime to yield enhancement due to heating and to experimentally measurable parameters, was derived by US researchers in collaboration with UPM [Phys. Rev. Lett. 114, (2015)]. Mission 2. Towards demonstration of shock ignition (SI) on MJ class laser facilities Evaluation of the letters on intent (LoI) received in response of the 1 st call for academic access of the LMJ PETAL facility led to pre selection of 8 of them were asked for a more detailed proposal by April Among the 4 proposals that were then finally scheduled on the facility in ( de l appel d offre LMJ.html), 2 of them are directly based on ToIFE activities: (i) Strong shock generation by laser plasma interaction in presence or not of laser smoothing (SSD) in the context of shock ignition studies on LMJ PETAL facility led by LULI and CELIA, in collaboration with IPPLM, CNR, York and Rochester Universities (task 2.1 completed) and (ii) Study of the interplay between B field and heat transport in ICF conditions (task 1.3.3). The success rate of the ToIFE supported proposals acknowledges the strong expertise and coordination reached within the project. The 2 nd call will be launched mid 2016; the ToIFE partners are prepared to submit new proposals. In the meantime, experiments, conducted by a CELIA US collaboration, are on the OMEGA laser facility in spherical geometry; positive influence on the shock strength (reaching Gbar pressures upon convergence) of the hot electrons generated by parametric instabilities was for instance demonstrated. Mission 3. Testing the feasibility of fast ignition (FI), impact ignition or other alternative schemes In that framework, a new ICF concept of auxiliary heating was developed to overcome drive asymmetries and hydro instabilities in low adiabat implosions (CCFE) [10]. A new analytical model for relativistic laser hole boring (initially proposed in the original FI scheme to maximize the delivered energy flux to the WPENR_AWP15_interim_report_CEA 02 2

3 fuel core) was also developed by CCFE and verified against 3D PIC simulations performed by IST on the latest HPC platforms. It shows that the deleterious effects of the hosing instability, which increase with density (as shown for the 1 st time analytically), can be mitigated by the use of strongly relativistic laser pulses, the huge ponderomotive pressure being thus able to quickly self correct channel distortions [4]. Finally, ion beam requirements for fast ignition were also investigated, thanks to inclusion in the numerical simulations of new effects, such as ion beam divergence, by UPM in collaboration with a Japanese colleague. The ions were supposed to be generated by the TNSA scheme in a curved foil placed inside a re entrant cone to allow focusing on the cone apex or beyond [Phys. Plasmas 22, (2015)]. Mission 4. Developing key IFE technologies In order to simulate the mechanical response of silica (i.e. final optics) to swift ion irradiation, a methodology based on molecular dynamics (MD) and finite element methods (FEM) was developed by UPM; it was shown that, although stress relaxation occurs due to plasticization, it cannot explain the drop in the refractive index observed at high ion fluencies at the CMAM accelerator. 2. Project deliverables No deliverable was supposed to be completed after 12 months. The following list gives the status of some soon to be achieved or deliverables, emphasizing the major collaborative activities conducted by the partners within the project. Task 1.2.3: demonstration of the relevance of isolated µm scale targets for PIC code validation Task 1.3.1: comprehensive study of foam smoothing effects Task 1.4.1: comprehensive study of ion energy loss in hot plasmas (due date: 18 months) Task 2.1: SI dedicated proposal to apply for fully See section 1. WPENR_AWP15_interim_report_CEA 02 3 Single truly isolated spherical targets, levitating thanks to the Paul trap developed at MPQ, were irradiated at GSI and at the Texas laser facility. Data are under analysis and comparison to extensive PIC simulations. A mitigation effect of a foam coating on the development of the Rayleigh Taylor instability was for the first time experimentally evidenced in planar geometry on the OMEGA laser facility. CELIA PARAX and CHIC simulations demonstrated a significant laser imprint reduction, due to parametric instabilities in the foam plasma, and a consequent delay in the instability growing. In parallel, laser energy absorption and transmission in foam plasmas were studied by ENEA. A comparison between perturbative and non perturbative models revealed discrepancies of up to 30% for stopping powers at their maximum. Benchmarking experiments are at the GSI Z6 experiment station, in collaboration with CELIA; a 1 st step aiming at characterising the ion source (UNILAC ions being decelerated to the adequate velocities through a degrader foil) was completed.

4 access on LMJ Task 3.1.1: full validation of the capacitor coil target concept for electron guiding Task 3.2.1: proof of principle of laser to ion conversions efficiencies above 10% Task 3.3: demonstrating macro particle velocities above 100km/s Task 3.4: clear evidence of p B fusion reactions Task 4.3: quantification of electromagnetic pulses produced by laser matter interaction Task 4.4.2: reproducing fusion ion bursts in the lab Task 1.1.5: demonstrating isolated attosecond harmonics at high repetition rate Task 2.2: simulation platform made available to the European academic community Reproducible quasi static B field generation by laser interaction with capacitorcoil targets was demonstrated, typically with a few ns duration and a mm 3 volume, yielding peak strengths of several hundreds Tesla, depending on the target material [11]. The 1 st tests of the compact cryostat, specifically designed by INAC/SBT in France for efficient proton acceleration from H ice plasmas, were successfully conducted at PALS (IPP.CR). Further experiments are scheduled on ELFIE (LULI) early Using the laser induced cavity pressure acceleration (LICPA) scheme proposed by IPPLM, an aluminium macro particle (of several µg) was accelerated at PALS (IPP.CR) to velocities of 100 km/s with an efficiency of 15%, for laser energy of only ~200J [2]. particles from p B reactions have been evidenced on ABC (ENEA) and ELFIE (LULI) for varied experimental configurations (including LICPA in collaboration with IPPLM) thanks to diagnostic improvements but further analysis is still required. EMP analysis has been performed by use of antennas and electric field sensors on ABC (ENEA) and PALS (IPP.CR) and correlations with laser target parameters investigated; PIC simulations were done to support interaction understanding. Efficient neutron production (up to n/j) was shown to be feasible at PALS (IPP.CR) thanks to a pitcher catcher scheme. ROM harmonics were generated up to the 60 th order on the LWS20 laser facility at MPQ, in collaboration with HAS, thanks to contrast improvements of the 5fs pulses and tight focusing, up to W/cm 2. The CELIA CHIC rad hydro code was enriched with two new physical modules describing laser beam transport in an underdense plasma, crossed beam energy transfer and hot electron generation (due to parametric instabilities) & transport. The laser energy transport model is based on a paraxial complex geometrical optics (PCGO) approach; compared to the standard ray tracing approach, this thick ray model allows reconstruction of the laser intensity pattern in the plasma and description of speckled beams with a controlled contrast level [12]. WPENR_AWP15_interim_report_CEA 02 4

5 Task 4.4.5: review of the HiPER reactor design A multiscale integral analysis, covering the whole tritium cycle within a nuclear fusion power plant, is currently developed by UPM. Tritium leakages was more especially studied. 3. Publications/presentations Note that, considering the low level of funding, none of the activities carried out in the framework of the ToIFE is substantially supported by EUROfusion. However, the following publications acknowledge the programme, among others. [1] Aladi M. et al., Noble gas clusters and nanoplasmas in high harmonic generation, Nucl. Instrum. Meth. B in press [2] Badziak J et al., Generation of ultra high pressure shocks by collision of a fast plasma projectile driven in the laser induced cavity pressure acceleration scheme with a solid target, Phys. Plasmas 22, (2015) [3] Belkhiri M et al., Influence of the plasma environment on atomic structure using an ion sphere model, Phys. Rev. A 92, (2015) [4] Ceurvost L. et al., Mitigating the hosing instability in relativistic laser plasma interactions, submitted to New J. Phys. [5] Colaitis A. et al., Crossed Beam Energy Transfer (CBET): assessment of the Paraxial Complex Geometrical Optics approach versus a time dependent paraxial to describe experimental results, submitted to Phys. Plasmas [6] Colaitis A. et al., Modeling of energy transfer between two crossing smoothed laser beams in a plasma with flow profile, submitted to J. Phys. Conf. Ser. [7] Dozières M. et al., X ray opacity measurements in mid Z dense plasmas with a new target design of indirect heating, HEDP 17, 231 (2015) [8] Pisarczyk T et al., Pre plasma effect on laser beam energy transfer to a dense target under conditions relevant to shock ignition, Laser & Part. Beams 33, 221 (2015) [9] Poirier M., A study of density effects in plasmas using analytical approximation for the self consistent potential, HEDP 15, 12 (2015) [10] Ratan N. et al., Dense plasma heating using colliding relativistic electron beams, submitted to Phys. Rev. Lett. [11] Santos J.J. et al., Laser driven platform for generation and characterization of strong quasi static magnetic fields, New J. Phys. 17, (2015) [12] Tikhonchuk V. et al., Physics of Laser Plasma Interaction and Shock Ignition of Fusion Reactions, Plasma Phys. Control. Fusion 58, (2016) 4. Managerial aspects (optional) The Czech Ministry of Education Youth and Sports (MŠMT) is stopping its financial support to the PALS laser infrastructure which may affect operation of this facility and jeopardize the chances of success of IPP.CR and IPPLM missions which rely on access to PALS, especially those on laser accelerated ion or macro particle sources. WPENR_AWP15_interim_report_CEA 02 5