Title: Diagnostics, Control and Performance Parameters for the BELLA High Repetition Rate Petawatt Class Laser

Abstract

A laser system producing controllable and stable pulses with high power and ultrashort duration at high repetition rate is a key component of a high energy laser-plasma accelerator (LPA). Precise characterization and control of laser properties are essential to understanding laser-plasma interactions required to build a 10-GeV class LPA. This study discusses the diagnostics, control and performance parameters of a 1 Hz, 1 petawatt (PW) class laser at the Berkeley Lab Laser Accelerator (BELLA) facility. The BELLA PW laser provided up to 46 J on target with a 1% level energy fluctuation and 1.3-μrad pointing stability. The spatial profile was measured and optimized by using a camera, wavefront sensor, and deformable mirror (ILAO system). The focus waist was measured to be r₀ = 53 μm and the fraction of energy within the circular area defined by the first minimum of the diffraction pattern (r = 67 μm) was 0.75. The temporal profile was controlled via the angle of incidence on a stretcher and a compressor, as well as an acousto-optic programmable dispersive. The temporal pulse shape was measured to be about 33 fs in full width at half maximum (WIZZLER and GRENOUILLE diagnostics). In order to accurately evaluate peak intensity,more » the energy-normalized peak fluence, and energy-normalized peak power were analyzed for the measured spatial and temporal mode profiles, and were found to be 15 kJ/(cm² J) with 6% fluctuation (standard deviation) and 25 TW/J with 5% fluctuation for 46-J on-target energy, respectively. This yielded a peak power of 1.2 PW and a peak intensity of 17×10¹⁸ W/cm² with 8% fluctuation. A method to model the pulse shape for arbitrary compressor grating distance with high accuracy was developed. The pulse contrast above the amplified spontaneous emission pedestal was measured by SEQUOIA and found to be better than 10⁹. The first order spatiotemporal couplings (STCs) were measured with GRENOUILLE, and a simulation of the pulse's evolution at the vicinity of the target was presented. A maximum pulse front tilt angle of less than 7 mrad was achieved. The reduction of the peak power caused by the first order STCs was estimated to be less than 1%. Finally, the capabilities described in this paper are essential for generation of high quality electron beams.« less

Authors:

Nakamura, Kei  ^[1];

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Mao, Hann-Shin ^[1]; Gonsalves, Anthony J. ^[1]; Vincenti, Henri ^[2]; Mittelberger, Daniel E. ^[3]; Daniels, Joost ^[4]; Magana, Arturo ^[1]; Toth, Csaba ^[1]; Leemans, Wim P. ^[3]

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+ Show Author Affiliations

1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Alternative Energies and Atomic Energy Commission (CEA), Saclay (France). Lasers, Interactions and Dynamics Lab.
3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Eindhoven Univ. of Technology (Netherlands)

Publication Date:

Thu May 25 00:00:00 EDT 2017

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), High Energy Physics (HEP); National Science Foundation (NSF)

OSTI Identifier:

1436636

Grant/Contract Number:  

AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

IEEE Journal of Quantum Electronics

Additional Journal Information:

Journal Volume: 53; Journal Issue: 4; Journal ID: ISSN 0018-9197

Publisher:

IEEE

Country of Publication:

United States

Language:

English

Subject:

47 OTHER INSTRUMENTATION; chirped-pulse amplification; Ti:Sapphire lasers; adaptive optics; spatiotemporal couplings; laser-plasma accelerators