2011 Particle Accelerator Conference - List of Authors (Welch, J.R.)

Paper	Title	Page
MOP231	Absolute Beam Flux Measurement at NDCX-I Using Gold-Melting-Calorimetry Technique	540
	P.N. Ni, F.M. Bieniosek, S.M. Lidia LBNL, Berkeley, California, USA J.R. Welch Cornell University, Ithaca, New York, USA
	Funding: Supported by the U.S. Department of Energy under Contracts No. DE-AC02-05CH11231 and DE-AC52-07NA27344. We report on an alternative way to measure beam fluence at NDCX-I, which is necessary for numerical simulation and planning of warm-dense-matter (WDM) experiments. So far the NDCX-I beam fluence has been characterized using a fast Faraday cup, radiation from a scintillator and tungsten foil calorimeter techniques. The present beam intensity is sufficient to melt and partially evaporate a 150 nm thick gold foil. Thermal emission (function of temperature) of the gold foil in the visible spectrum was measured during beam irradiation. A distinct shelf in the thermal emission intensity was observed after 600 ns, indicating that the sample reached the melting temperature. Using known heat capacity and latent heat of melting, the beam flux fully determines the duration of the melting shelf and the moment it appears. Using this technique we estimate an average 260 kW/cm² beam flux over 10μs, which is consistent with values provided by the other methods.

Paper

Title

Page

Absolute Beam Flux Measurement at NDCX-I Using Gold-Melting-Calorimetry Technique

540

P.N. Ni, F.M. Bieniosek, S.M. Lidia
LBNL, Berkeley, California, USA
J.R. Welch
Cornell University, Ithaca, New York, USA

Funding: Supported by the U.S. Department of Energy under Contracts No. DE-AC02-05CH11231 and DE-AC52-07NA27344.
We report on an alternative way to measure beam fluence at NDCX-I, which is necessary for numerical simulation and planning of warm-dense-matter (WDM) experiments. So far the NDCX-I beam fluence has been characterized using a fast Faraday cup, radiation from a scintillator and tungsten foil calorimeter techniques. The present beam intensity is sufficient to melt and partially evaporate a 150 nm thick gold foil. Thermal emission (function of temperature) of the gold foil in the visible spectrum was measured during beam irradiation. A distinct shelf in the thermal emission intensity was observed after 600 ns, indicating that the sample reached the melting temperature. Using known heat capacity and latent heat of melting, the beam flux fully determines the duration of the melting shelf and the moment it appears. Using this technique we estimate an average 260 kW/cm² beam flux over 10μs, which is consistent with values provided by the other methods.