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Title: Concomitant Hamiltonian and topological structures of extended magnetohydrodynamics

Authors:
; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1347255
Grant/Contract Number:
AC02-09CH-11466; FG02-04ER-54742
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physics Letters. A
Additional Journal Information:
Journal Volume: 380; Journal Issue: 31-32; Related Information: CHORUS Timestamp: 2017-10-06 21:54:57; Journal ID: ISSN 0375-9601
Publisher:
Elsevier
Country of Publication:
Netherlands
Language:
English

Citation Formats

Lingam, Manasvi, Miloshevich, George, and Morrison, Philip J. Concomitant Hamiltonian and topological structures of extended magnetohydrodynamics. Netherlands: N. p., 2016. Web. doi:10.1016/j.physleta.2016.05.024.
Lingam, Manasvi, Miloshevich, George, & Morrison, Philip J. Concomitant Hamiltonian and topological structures of extended magnetohydrodynamics. Netherlands. doi:10.1016/j.physleta.2016.05.024.
Lingam, Manasvi, Miloshevich, George, and Morrison, Philip J. 2016. "Concomitant Hamiltonian and topological structures of extended magnetohydrodynamics". Netherlands. doi:10.1016/j.physleta.2016.05.024.
@article{osti_1347255,
title = {Concomitant Hamiltonian and topological structures of extended magnetohydrodynamics},
author = {Lingam, Manasvi and Miloshevich, George and Morrison, Philip J.},
abstractNote = {},
doi = {10.1016/j.physleta.2016.05.024},
journal = {Physics Letters. A},
number = 31-32,
volume = 380,
place = {Netherlands},
year = 2016,
month = 7
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.physleta.2016.05.024

Citation Metrics:
Cited by: 13works
Citation information provided by
Web of Science

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  • Purpose: Positron emission tomography/computed tomography (PET/CT) is commonly used for nodal staging in locally advanced cervical cancer; however the false negative rate for para-aortic disease are 20% to 25% in PET-positive pelvic nodal disease. Unless surgically staged, pelvis-only treatment may undertreat para-aortic disease. We have treated patients with PET-positive nodes with extended field intensity modulated radiation therapy (IMRT) to address the para-aortic region prophylactically with concomitant boost to involved nodes. The purpose of this study was to assess regional control rates and recurrence patterns. Methods and Materials: Sixty-one patients with cervical cancer (stage IBI-IVA) diagnosed from 2003 to 2012 withmore » PET-avid pelvic nodes treated with extended field IMRT (45 Gy in 25 fractions with concomitant boost to involved nodes to a median of 55 Gy in 25 fractions) with concurrent cisplatin and brachytherapy were retrospectively analyzed. The nodal location was pelvis-only in 41 patients (67%) and pelvis + para-aortic in 20 patients (33%). There were a total of 179 nodes, with a median number of positive nodes of 2 (range, 1-16 nodes) per patient and a median nodal size of 1.8 cm (range, 0.7-4.5 cm). Response was assessed by PET/CT at 12 to 16 weeks. Results: Complete clinical and imaging response at the first follow-up visit was seen in 77% of patients. At a mean follow-up time of 29 months (range, 3-116 months), 8 patients experienced recurrence. The sites of persistent/recurrent disease were as follows: cervix 10 (16.3%), regional nodes 3 (4.9%), and distant 14 (23%). The rate of para-aortic failure in patients with pelvic-only nodes was 2.5%. There were no significant differences in recurrence patterns by the number/location of nodes, largest node size, or maximum node standardized uptake value. The rate of late grade 3+ adverse events was 4%. Conclusions: Extended field IMRT was well tolerated and resulted in low regional recurrence in node-positive cervical cancer. The dose of 55 Gy in 25 fractions was effective in eradicating disease in involved nodes, with acceptable late adverse events. Distant metastasis is the predominant mode of failure, and the OUTBACK trial may challenge the presented paradigms.« less
  • In this study, it is shown that the two-fluid model under a generalized Ohm’s law formulation and the resistive magnetohydrodynamics (MHD) can both be described as relaxation systems. In the relaxation model, the under-resolved stiff source terms constrain the dynamics of a set of hyperbolic equations to give the correct asymptotic solution. When applied to the collisional two-fluid model, the relaxation of fast time scales associated with displacement current and finite electron mass allows for a natural transition from a system where Ohm’s law determines the current density to a system where Ohm’s law determines the electric field. This resultmore » is used to derive novel algorithms, which allow for multiscale simulation of low and high frequency extended-MHD physics. This relaxation formulation offers an efficient way to implicitly advance the Hall term and naturally simulate a plasma-vacuum interface without invoking phenomenological models. The relaxation model is implemented as an extended-MHD code, which is used to analyze pulsed power loads such as wire arrays and ablating foils. Two-dimensional simulations of pulsed power loads are compared for extended-MHD and MHD. For these simulations, it is also shown that the relaxation model properly recovers the resistive-MHD limit.« less
  • In this study, it is shown that the two-fluid model under a generalized Ohm’s law formulation and the resistive magnetohydrodynamics (MHD) can both be described as relaxation systems. In the relaxation model, the under-resolved stiff source terms constrain the dynamics of a set of hyperbolic equations to give the correct asymptotic solution. When applied to the collisional two-fluid model, the relaxation of fast time scales associated with displacement current and finite electron mass allows for a natural transition from a system where Ohm’s law determines the current density to a system where Ohm’s law determines the electric field. This resultmore » is used to derive novel algorithms, which allow for multiscale simulation of low and high frequency extended-MHD physics. This relaxation formulation offers an efficient way to implicitly advance the Hall term and naturally simulate a plasma-vacuum interface without invoking phenomenological models. The relaxation model is implemented as an extended-MHD code, which is used to analyze pulsed power loads such as wire arrays and ablating foils. Two-dimensional simulations of pulsed power loads are compared for extended-MHD and MHD. For these simulations, it is also shown that the relaxation model properly recovers the resistive-MHD limit.« less
    Cited by 20
  • It is shown that the two-fluid model under a generalized Ohm's law formulation and the resistive magnetohydrodynamics (MHD) can both be described as relaxation systems. In the relaxation model, the under-resolved stiff source terms constrain the dynamics of a set of hyperbolic equations to give the correct asymptotic solution. When applied to the collisional two-fluid model, the relaxation of fast time scales associated with displacement current and finite electron mass allows for a natural transition from a system where Ohm's law determines the current density to a system where Ohm's law determines the electric field. This result is used tomore » derive novel algorithms, which allow for multiscale simulation of low and high frequency extended-MHD physics. This relaxation formulation offers an efficient way to implicitly advance the Hall term and naturally simulate a plasma-vacuum interface without invoking phenomenological models. The relaxation model is implemented as an extended-MHD code, which is used to analyze pulsed power loads such as wire arrays and ablating foils. Two-dimensional simulations of pulsed power loads are compared for extended-MHD and MHD. For these simulations, it is also shown that the relaxation model properly recovers the resistive-MHD limit.« less