Electromagnetic Pulses at Short-Pulse Laser Facilities

Conference · Mon Feb 04 00:00:00 EST 2008

DOI:https://doi.org/10.1088/1742-6596/112/3/032025· OSTI ID:926016

Brown, C G; Throop, A; Eder, D; Kimbrough, J

Electromagnetic Pulse (EMP) is a known issue for short-pulse laser facilities, and will also be an issue for experiments using the advanced radiographic capability (ARC) at the National Ignition Facility (NIF). The ARC diagnostic uses four NIF beams that are compressed to picosecond durations for backlighting ignition capsules and other applications. Consequently, we are working to understand the EMP due to high-energy (MeV) electrons escaping from targets heated by short-pulse lasers. Our approach is to measure EMP in the Titan short-pulse laser at Lawrence Livermore National Laboratory (LLNL) and to employ that data to establish analysis and simulation capabilities. We have installed a wide variety of probes inside and outside the Titan laser chamber. We have high-frequency B-dot and D-dot probes, a photodiode, and fast current-viewing and integrating current transformers. The probe outputs are digitized by 10 and 20 Gsample/s oscilloscopes. The cables and oscilloscopes are well shielded to reduce noise. Our initial measurement campaign has yielded data useful mainly from several hundreds of MHz to several GHz. We currently are supplementing our high-frequency probes with lower-frequency ones to obtain better low-frequency data. In order to establish analysis and simulation capabilities we are modeling the Titan facility using various commercial and LLNL numerical electromagnetics codes. We have simulated EMP generation by having a specified number of electrons leave the target and strike the chamber wall and other components in the chamber. This short impulse of electrons has a correspondingly broad spectrum, exciting high-frequency structure in the resulting EMP. In this paper, we present results of our initial measurement campaign and comparisons between the measurements and simulations.

• Research Organization: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 926016
• Report Number(s): LLNL-CONF-401192; TRN: US200807%%466
• Resource Relation: Journal Volume: 112; Journal Issue: 3; Conference: Presented at: IFSA Conference 2007, Kobe, Japan, Sep 09 - Sep 14, 2007
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
CABLES
DIAGNOSTIC USES
ELECTROMAGNETIC PULSES
ELECTRONS
IGNITION
LASERS
LAWRENCE LIVERMORE NATIONAL LABORATORY
PROBES
SIMULATION
TARGETS
TRANSFORMERS
US NATIONAL IGNITION FACILITY