Publications
Single-Shot Imaging of Plasma Jet Dynamics and Laser Shockwave Propagation in Low-Density Voids
https://meetings-archive.aps.org/dpp/2024/zo07/13
D. Hodge et al.
The recent record-breaking 5.2 MJ yield in Inertial Fusion Energy (IFE) at the National ignition Facility (NIF) highlights nuclear fusion's potential as a sustainable, limitless energy source. However, voids and other defects in the IFE capsule ablator material induce hydrodynamic instabilities, leading to plasma jetting and lower compression, limiting fusion yield. Therefore, maximizing energy yield and generating sufficient energy for practical power plant implementation requires dynamic, high-resolution characterization of ablator materials during laser shock compression. To address these challenges, our team has implemented x-ray phase contrast imaging (XPCI) of plasma jets and phase transformations at the Linac Coherent Light Source (LCLS) Matter in Extreme Conditions (MEC) instrument. Here, we use a sample of SU-8 embedded with an SiO2 glass shell to imitate an IFE ablator and void. By comparing experimental images with xRAGE hydrodynamic code simulations, we tune parameters to match experimental shock physics, providing insights to mitigate or leverage voids for maximum yield. For quantitative analysis, we apply phase retrieval techniques to extract phase from complex, dynamic images, potentially revolutionizing compression approaches and enhancing computational models of void collapse.
Ultra-fast transverse beam orbit control in LCLS copper linac. Part I
https://doi.org/10.1088/1748-0221/17/11/P11031
A. Halavanau, A. Romero, A. Krasnykh, A. Lutman, T. Beukers, J. Hugyik, A. Le, K. Luchini, E. Jongewaard, A. Sy
Current and future experiments at LCLS require x-ray pulse trains of variable time separation on the nanosecond scale. For instance, the cavity-based XFEL (CBXFEL) will use up to 4 pulses separated by 218.5 ns, the X-ray Laser Oscillator (XLO) will use 15 to 25 ns spaced pulses, and the Matter under Extreme Conditions (MEC) experiments use pulse trains separated by 5 nanoseconds or less. In this paper, we demonstrate an ultra-fast e-beam trajectory control method based on transverse electro-magnetic (TEM) striplines and state-of-the-art power sources, to enhance LCLS operations in these regimes.
LCLS Multi-Bunch Improvement Plan: First Results
https://jacow.org/ipac2022/papers/tupopt037.pdf
https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT037
A. Romero, A. Halavanau, A. Krasnykh, A. A. Lutman, T. Beukers, J. Hugyik, A. Le, K. Luchini, E. Jongewaard, A. Sy, A. Ibrahimov, L. Borzenets, M. M. Petree, A. Benwell, A. Marinelli, F. J. Decker
LCLS copper linac primarily operates in a single bunch mode with a repetition rate of 120 Hz. Presently, several inhouse projects and LCLS user experiments require double- and multi-pulse trains of X-rays, with inter-pulse delay spanning between 0.35 and 220 ns. We discuss beam control improvements to the copper linac using ultra-fast stripline kicker, as well as additional photon diagnostics. We especially focus on a case of double-pulse mode, with 220 ns separation.
High Efficiency Traveling Wave Linac With Tunable Energy
https://doi.org/10.18429/JACoW-LINAC2022-THPOJO16
https://accelconf.web.cern.ch/linac2022/papers/thpojo16.pdf
V. Dolgashev, A. Romero, A. Krasnykh, S. Kuzikov, R. Kostin, P. Borchard
We will present the physics design of a compact, highly efficient, energy-tunable 9.3 GHz linac to generate up to 500 W of 10 MeV electron beam power for medical and security applications. This linac will employ a patented travelling wave accelerating structure with outside power flow which combines the advantages of high efficiency with energy tunability of traveling wave cavities. Unlike standing wave structures, the proposed structure has little power reflected back to the RF source, eliminating the need for a heavy, lossy waveguide isolator. In contrast to the side-coupled cavity designs, the proposed structure is symmetrical and therefore it does not have deflecting axial fields that impair the beam transport. The high shunt impedance will allow the linac to achieve an output energy of up to 10 MeV when powered by a compact commercial 9.3 GHz 1.7 MW magnetron. For pulse-to-pulse tuning of the beam output energy we will change the beam-loaded gradient by varying the linac's triode gun current.