Education & Certifications


  • PhD, The University of Texas at Austin, Physics, Physics (2015)
  • M.S., National Taiwan University, Electrical Engineering and Computer Science, Photonics and Optoelectronics (2005)
  • B.S., National Taiwan University, Physics, Physics (2002)

All Publications


  • Reduced bandwidth Compton photons from a laser-plasma accelerator using tailored plasma channels PHYSICS OF PLASMAS Grote, D. P., Friedman, A., Geddes, C. R., Lehe, R., Benedetti, C., Ostermayr, T. M., Tsai, H., Vay, J., Schroeder, C. B., Esarey, E. 2021; 28 (12)

    View details for DOI 10.1063/5.0073622

    View details for Web of Science ID 000730516400002

  • High-power non-perturbative laser delivery diagnostics at the final focus of 100-TW-class laser pulses HIGH POWER LASER SCIENCE AND ENGINEERING Isono, F., van Tilborg, J., Barber, S. K., Natal, J., Berger, C., Tsai, H., Ostermayr, T., Gonsalves, A., Geddes, C., Esarey, E. 2021; 9
  • Gas density structure of supersonic flows impinged on by thin blades for laser-plasma accelerator targets PHYSICS OF FLUIDS Fan-Chiang, L., Mao, H., Tsai, H., Ostermayr, T., Swanson, K. K., Barber, S. K., Steinke, S., van Tilborg, J., Geddes, C. R., Leemans, W. P. 2020; 32 (6)

    View details for DOI 10.1063/5.0005888

    View details for Web of Science ID 000546939300001

  • Parametric emittance measurements of electron beams produced by a laser plasma accelerator PLASMA PHYSICS AND CONTROLLED FUSION Barber, S. K., van Tilborg, J., Schroeder, C. B., Lehe, R., Tsai, H., Swanson, K. K., Steinke, S., Nakamura, K., Geddes, C. R., Benedetti, C., Esarey, E., Leemans, W. P. 2018; 60 (5)
  • Comparative study of active plasma lenses in high-quality electron accelerator transport lines van Tilborg, J., Barber, S. K., Benedetti, C., Schroeder, C. B., Isono, F., Tsai, H., Geddes, C. R., Leemans, W. P. AMER INST PHYSICS. 2018

    View details for DOI 10.1063/1.5018001

    View details for Web of Science ID 000433961800153

  • Control of quasi-monoenergetic electron beams from laser-plasma accelerators with adjustable shock density profile PHYSICS OF PLASMAS Tsai, H., Swanson, K. K., Barber, S. K., Lehe, R., Mao, H., Mittelberger, D. E., Steinke, S., Nakamura, K., van Tilborg, J., Schroeder, C., Esarey, E., Geddes, C. R., Leemans, W. 2018; 25 (4)

    View details for DOI 10.1063/1.5023694

    View details for Web of Science ID 000431142200053

  • A tabletop, ultrashort pulse photoneutron source driven by electrons from laser wakefield acceleration MATTER AND RADIATION AT EXTREMES Jiao, X. J., Shaw, J. M., Wang, T., Wang, X. M., Tsai, H., Poth, P., Pomerantz, I., Labun, L. A., Toncian, T., Downer, M. C., Hegelich, B. M. 2017; 2 (6): 296-302
  • Measured Emittance Dependence on the Injection Method in Laser Plasma Accelerators PHYSICAL REVIEW LETTERS Barber, S. K., van Tilborg, J., Schroeder, C. B., Lehe, R., Tsai, H., Swanson, K. K., Steinke, S., Nakamura, K., Geddes, C. R., Benedetti, C., Esarey, E., Leemans, W. P. 2017; 119 (10): 104801

    Abstract

    Single-shot, charge-dependent emittance measurements of electron beams generated by a laser plasma accelerator (LPA) reveal that shock-induced density down-ramp injection produces beams with normalized emittances a factor of 2 smaller than beams produced via ionization injection. Such a comparison is made possible by the tunable LPA setup, which allows electron beams with nearly identical central energy and peak spectral charge density to be produced using the two distinct injection mechanisms. Parametric measurements of this type are essential for the development of LPA-based applications which ultimately require high charge density and low emittance.

    View details for DOI 10.1103/PhysRevLett.119.104801

    View details for Web of Science ID 000409265000004

    View details for PubMedID 28949165

  • Control of tunable, monoenergetic laser-plasma-accelerated electron beams using a shock-induced density downramp injector PHYSICAL REVIEW ACCELERATORS AND BEAMS Swanson, K. K., Tsai, H., Barber, S. K., Lehe, R., Mao, H., Steinke, S., van Tilborg, J., Nakamura, K., Geddes, C. R., Schroeder, C. B., Esarey, E., Leemans, W. P. 2017; 20 (5)
  • Self-aligning concave relativistic plasma mirror with adjustable focus PHYSICS OF PLASMAS Tsai, H., Arefiev, A. V., Shaw, J. M., Stark, D. J., Wang, X., Zgadzaj, R., Downer, M. C. 2017; 24 (1)

    View details for DOI 10.1063/1.4973432

    View details for Web of Science ID 000395395100055

  • Compact Tunable Compton X-ray Source from Laser Wakefield Accelerator and Plasma Mirror Tsai, H., Wang, X., Shaw, J., Arefiev, A. V., Li, Z., Zhang, X., Zgadzaj, R., Henderson, W., Khudik, V., Shvets, G., Downer, M. C., Hogan, M. J. AMER INST PHYSICS. 2016

    View details for DOI 10.1063/1.4965663

    View details for Web of Science ID 000389510300074

  • Compact tunable Compton x-ray source from laser-plasma accelerator and plasma mirror PHYSICS OF PLASMAS Tsai, H., Wang, X., Shaw, J. M., Li, Z., Arefiev, A. V., Zhang, X., Zgadzaj, R., Henderson, W., Khudik, V., Shvets, G., Downer, M. C. 2015; 22 (2)

    View details for DOI 10.1063/1.4907655

    View details for Web of Science ID 000350552000100

  • Single-Shot Visualization of Evolving Laser Wakefields Using an All-Optical Streak Camera PHYSICAL REVIEW LETTERS Li, Z., Tsai, H., Zhang, X., Pai, C., Chang, Y., Zgadzaj, R., Wang, X., Khudik, V., Shvets, G., Downer, M. C. 2014; 113 (8): 085001

    Abstract

    We visualize ps-time-scale evolution of an electron density bubble--a wake structure created in atmospheric density plasma by an intense ultrashort laser pulse--from the phase "streak" that the bubble imprints onto a probe pulse that crosses its path obliquely. Phase streaks, recovered in one shot using frequency-domain interferometric techniques, reveal the formation, propagation, and coalescence of the bubble within a 3 mm long ionized helium gas target. 3D particle-in-cell simulations validate the observed density-dependent bubble evolution, and correlate it with the generation of a quasimonoenergetic ∼ 100 MeV electron beam. The results provide a basis for understanding optimized electron acceleration at a plasma density n(e) ≈ 2 × 10(19) cm(-3), inefficient acceleration at lower density, and dephasing limits at higher density.

    View details for DOI 10.1103/PhysRevLett.113.085001

    View details for Web of Science ID 000341247600005

    View details for PubMedID 25192102

  • Quasi-monoenergetic laser-plasma acceleration of electrons to 2 GeV NATURE COMMUNICATIONS Wang, X., Zgadzaj, R., Fazel, N., Li, Z., Yi, S. A., Zhang, X., Henderson, W., Chang, Y., Korzekwa, R., Tsai, H., Pai, C., Quevedo, H., Dyer, G., Gaul, E., Martinez, M., Bernstein, A. C., Borger, T., Spinks, M., Donovan, M., Khudik, V., Shvets, G., Ditmire, T., Downer, M. C. 2013; 4: 1988

    Abstract

    Laser-plasma accelerators of only a centimetre's length have produced nearly monoenergetic electron bunches with energy as high as 1 GeV. Scaling these compact accelerators to multi-gigaelectronvolt energy would open the prospect of building X-ray free-electron lasers and linear colliders hundreds of times smaller than conventional facilities, but the 1 GeV barrier has so far proven insurmountable. Here, by applying new petawatt laser technology, we produce electron bunches with a spectrum prominently peaked at 2 GeV with only a few per cent energy spread and unprecedented sub-milliradian divergence. Petawatt pulses inject ambient plasma electrons into the laser-driven accelerator at much lower density than was previously possible, thereby overcoming the principal physical barriers to multi-gigaelectronvolt acceleration: dephasing between laser-driven wake and accelerating electrons and laser pulse erosion. Simulations indicate that with improvements in the laser-pulse focus quality, acceleration to nearly 10 GeV should be possible with the available pulse energy.

    View details for DOI 10.1038/ncomms2988

    View details for Web of Science ID 000323624600011

    View details for PubMedID 23756359

    View details for PubMedCentralID PMC3709475

  • Self-injected petawatt laser-driven plasma electron acceleration in 10(17) cm(-3) plasma JOURNAL OF PLASMA PHYSICS Wang, X., Zgadzaj, R., Yi, S. A., Khudik, V., Henderson, W., Fazel, N., Chang, Y., Korzekwa, R., Tsai, H., Pai, C., Li, Z., Gaul, E., Martinez, M., Dyer, G., Quevedo, H., Bernstein, A., Donovan, M., Shvets, G., Ditmire, T., Downer, M. C. 2012; 78: 413-419
  • Petawatt-laser-driven wakefield acceleration of electrons to 2 GeV in 10(17)cm(-3) plasma Wang, X., Zgadzaj, R., Fazel, N., Yi, S. A., Zhang, X., Henderson, W., Chang, Y., Korzekwa, R., Tsai, H., Pai, C., Li, Z., Quevedo, H., Dyer, G., Gaul, E., Martinez, M., Bernstein, A., Borger, T., Spinks, M., Donovan, M., Kalmykov, S. Y., Khudik, V., Shvets, G., Ditmire, T., Downer, M. C., Zgadzaj, R., Gaul, E., Downer, M. C. AMER INST PHYSICS. 2012: 341-344

    View details for DOI 10.1063/1.4773719

    View details for Web of Science ID 000315058700043

  • Characterization and control of plasma density distribution for the development of solid-target x-ray lasers PHYSICAL REVIEW E Chou, M. C., Lin, P. H., Tsai, H. E., Chen, D. L., Lee, C. H., Lin, J. Y., Wang, J., Chen, S. Y. 2005; 72 (2): 026407

    Abstract

    By using deflectometry of a longitudinal probe pulse and reflective interferometry of a transverse probe pulse to resolve the spatiotemporal distribution of the preformed plasma, we characterize and control the plasma density distribution near the target surface for the development of solid-target x-ray lasers. We show that the use of prepulses in an ignitor-heater scheme can increase the scale length of the preformed plasma and how the effect varies with target materials. Many important issues crucial to x-ray lasing such as electron density distribution, electron temperature, and the optimal timing between pumping pulses can be resolved with these methods.

    View details for DOI 10.1103/PhysRevE.72.026407

    View details for Web of Science ID 000231564100095

    View details for PubMedID 16196718

  • Collisional excitation soft x-ray laser pumped by optical field ionization in a cluster jet PHYSICAL REVIEW A Chu, H. H., Tsai, H. E., Chou, M. C., Yang, L. S., Lin, J. Y., Lee, C. H., Wang, J., Chen, S. Y. 2005; 71 (6)
  • Control of laser-beam propagation and absorption in a nanoplasma gas by programming of a transient complex refractive index with a prepulse PHYSICAL REVIEW E Chu, H. E., Tsai, H. E., Xiao, Y. F., Lee, C. H., Lin, J. Y., Wang, J., Chen, S. Y. 2004; 69 (3): 035403

    Abstract

    By utilizing the intensity- and duration-dependent heating and expansion rate of nanoplasma to generate a transient transverse gradient of the refractive index, prepulse controlled laser-beam propagation is demonstrated. The dynamical response of the macroscopic optical refractive index is traced back to the microscopic polarizability of nanoplasmas experimentally, in accordance with hydrodynamic nanoplasma models. In particular, the delay between the prepulse and the main pulse for maximum Rayleigh scattering is found to be longer than that for maximum x-ray emission, supporting the more refined one-dimensional self-consistent hydrodynamic nanoplasma model.

    View details for DOI 10.1103/PhysRevE.69.035403

    View details for Web of Science ID 000220729400009

    View details for PubMedID 15089352