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Title: Fast Imaging of Intact and Shattered Cryogenic Neon Pellets

Abstract

Compact condensed-matter injection technologies are increasingly used in magnetic fusion. One recent application is in disruption mitigation. An imaging system with less-than-100- m- and sub- s-resolution is described and used to characterize intact and shattered cryogenic neon pellets. Shattered pellets contain fine particles ranging from tens of m to about 7 mm. Time-of-flight analyses indicate that pellets could slow down if hitting the wall of the guide tube. Fast high-resolution imaging systems are thus useful to neon and other condensed-matter injector development.

Authors:
 [1];  [2];  [2];  [2];  [2];  [2];  [2]
  1. Los Alamos National Laboratory (LANL)
  2. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1143588
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: 20th Topical Conference on High-Temperature Plasma Diagnostics (HTPD), Atlanta, GA, USA, 20140601, 20140605
Country of Publication:
United States
Language:
English

Citation Formats

Wang, Zhehui, Combs, Stephen Kirk, Baylor, Larry R, Foust, Charles R, Lyttle, Mark S, Meitner, Steven J, and Rasmussen, David A. Fast Imaging of Intact and Shattered Cryogenic Neon Pellets. United States: N. p., 2014. Web.
Wang, Zhehui, Combs, Stephen Kirk, Baylor, Larry R, Foust, Charles R, Lyttle, Mark S, Meitner, Steven J, & Rasmussen, David A. Fast Imaging of Intact and Shattered Cryogenic Neon Pellets. United States.
Wang, Zhehui, Combs, Stephen Kirk, Baylor, Larry R, Foust, Charles R, Lyttle, Mark S, Meitner, Steven J, and Rasmussen, David A. 2014. "Fast Imaging of Intact and Shattered Cryogenic Neon Pellets". United States. doi:.
@article{osti_1143588,
title = {Fast Imaging of Intact and Shattered Cryogenic Neon Pellets},
author = {Wang, Zhehui and Combs, Stephen Kirk and Baylor, Larry R and Foust, Charles R and Lyttle, Mark S and Meitner, Steven J and Rasmussen, David A},
abstractNote = {Compact condensed-matter injection technologies are increasingly used in magnetic fusion. One recent application is in disruption mitigation. An imaging system with less-than-100- m- and sub- s-resolution is described and used to characterize intact and shattered cryogenic neon pellets. Shattered pellets contain fine particles ranging from tens of m to about 7 mm. Time-of-flight analyses indicate that pellets could slow down if hitting the wall of the guide tube. Fast high-resolution imaging systems are thus useful to neon and other condensed-matter injector development.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2014,
month = 1
}

Conference:
Other availability
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  • Compact condensed-matter injection technologies are increasingly used in magnetic fusion. One recent application is in disruption mitigation. An imaging system with less-than-100-µm- and sub-µs-resolution is described and used to characterize intact and shattered cryogenic neon pellets. Shattered pellets contain fine particles ranging from tens of µm to about 7 mm. Time-of-flight analyses indicate that pellets could slow down if hitting the wall of the guide tube. Fast high-resolution imaging systems are thus useful to neon and other condensed-matter injector development.
  • For over two decades Oak Ridge National Laboratory has been developing cryogenic pellet injectors for fueling hot, magnetic fusion plasmas. Cryogenic solid pellets of all three hydrogen isotopes have been produced in a size range of 1- to 10-mm diameter and accelerated to speeds from <100 to {approx}3000 m/s. The pellets have been formed discretely by cryocondensation in gun barrels and also by extrusion of cryogenic solids at mass flow rates up to {approx}0.26 g/s and production rates up to ten pellets per second. The pellets traverse the hot plasma in a fraction of a millisecond and continuously ablate, providingmore » fresh hydrogenic fuel to the interior of the plasma. From this initial application, uses of this technology have expanded to include (1) cryogenic xenon drops or solids for use as a debris-less target in a laser plasma source of X-rays for advanced lithography systems, (2) solid argon and carbon dioxide pellets for surface cleaning or decontamination, and (3) methane pellets in a liquid hydrogen bath for use as an innovative moderator of cold neutrons. Methods of production and acceleration/transport of these cryogenic solids will be described, and examples will be given of their use in prototype systems.« less
  • Injection of multiple large (~10 to 30 mm diameter) shattered pellets into ITER plasmas is presently part of the scheme planned to mitigate the deleterious effects of disruptions on the vessel components. To help in the design and optimize performance of the pellet injectors for this application, a model referred to as “the gas gun simulator” has been developed and benchmarked against experimental data. The computer code simulator is a Java program that models the gas-dynamics characteristics of a single-stage gas gun. Following a stepwise approach, the code utilizes a variety of input parameters to incrementally simulate and analyze themore » dynamics of the gun as the projectile is launched down the barrel. Using input data, the model can calculate gun performance based on physical characteristics, such as propellant-gas and fast-valve properties, barrel geometry, and pellet mass. Although the model is fundamentally generic, the present version is configured to accommodate cryogenic pellets composed of H2, D2, Ne, Ar, and mixtures of them and light propellant gases (H2, D2, and He). The pellets are solidified in situ in pipe guns that consist of stainless steel tubes and fast-acting valves that provide the propellant gas for pellet acceleration (to speeds ~200 to 700 m/s). The pellet speed is the key parameter in determining the response time of a shattered pellet system to a plasma disruption event. The calculated speeds from the code simulations of experiments were typically in excellent agreement with the measured values. With the gas gun simulator validated for many test shots and over a wide range of physical and operating parameters, it is a valuable tool for optimization of the injector design, including the fast valve design (orifice size and volume) for any operating pressure (~40 bar expected for the ITER application) and barrel length for any pellet size (mass, diameter, and length). Key design parameters and proposed values for the pellet injectors for the ITER disruption mitigation systems are discussed.« less
  • Boron neutron capture therapy (BNCT) is a proposed method of treating Glioblastoma Multiforme. BNCT is based on /sup 10/B intake by the tumor and in-situ activation by neutron beam. It is estimated that to have successful BNCT, a /sup 10/B delivery mechanism must deposit 20 ppM or more of /sup 10/B within the tumor. To study and understand this delivery mechanism, /sup 11/B can be used instead of /sup 10/B. The pharmacokinetics of any compound using /sup 11/B will be the same as /sup 10/B. The advantage of using /sup 11/B over /sup 10/B is its greater nuclear magnetic resonancemore » sensitivity for both spectroscopy and imaging. The use of /sup 11/B imaging to detect and quantitate boron uptake non-invasively in animal tumor modes will facilitate continued work with /sup 10/B. Preliminary work has shown that /sup 11/B nuclear magnetic resonance (NMR) spectroscopy (nonlocalized) can detect /sup 11/B in intact mouse tissues and the area under the boron peak correlates with the total boron content (correlation coefficient of 0.997). Once the ability to non-invasively measure the boron compound is established using magnetic resonance imaging (MRI) combined with spectroscopy, we will be able to address the following questions: (1) what is the optimum method of boron administration for maximum tumor selective uptake, (2) at what time is peak tumor boron concentration after infusion, and (3) what is the dose distribution in the head (based on neutron radiation and boron concentration). The purpose of this study was to test the feasibility of imaging /sup 11/B in intact tissues using magnetic resonance.« less
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