777 research outputs found
A high-voltage pulsed power modulator for fast-rising arbitrary waveforms
This work presents the design and testing of a new semiconductor-based pulsed power modulator meeting the challenging requirements of a pulsed electron beam device (GESA): a fast-rising (10^12 V/s) output voltage with arbitrary waveform of maximum 120 kV at a maximum current of 600 A for a pulse duration of up to 100 ”s
Small-scale properties of the KPZ equation and dynamical symmetry breaking
A functional integral technique is used to study the ultraviolet or short
distance properties of the Kardar-Parisi-Zhang (KPZ) equation with white
Gaussian noise. We apply this technique to calculate the one-loop effective
potential for the KPZ equation. The effective potential is (at least) one-loop
ultraviolet renormalizable in 1, 2, and 3 space dimensions, but
non-renormalizable in 4 or higher space dimensions. This potential is
intimately related to the probability distribution function (PDF) for the
spacetime averaged field. For the restricted class of field configurations
considered here, the KPZ equation exhibits dynamical symmetry breaking (DSB)
via an analog of the Coleman-Weinberg mechanism in 1 and 2 space dimensions,
but not in 3 space dimensions.Comment: V2 --- 6 pages, LaTeX 209, ReV_TeX 3.2. Title changed, presentation
clarified, additional discussion added, references updated. No significant
changes in physics conclusions. This version to appear in Physics Letters
Evolutionary medicine â the quest for a better understanding of health, disease and prevention
Effective potential for the massless KPZ equation
In previous work we have developed a general method for casting a classical
field theory subject to Gaussian noise (that is, a stochastic partial
differential equation--SPDE) into a functional integral formalism that exhibits
many of the properties more commonly associated with quantum field theories
(QFTs). In particular, we demonstrated how to derive the one-loop effective
potential. In this paper we apply the formalism to a specific field theory of
considerable interest, the massless KPZ equation (massless noisy vorticity-free
Burgers equation), and analyze its behaviour in the ultraviolet
(short-distance) regime. When this field theory is subject to white noise we
can calculate the one-loop effective potential and show that it is one-loop
ultraviolet renormalizable in 1, 2, and 3 space dimensions, and fails to be
ultraviolet renormalizable in higher dimensions. We show that the one-loop
effective potential for the massless KPZ equation is closely related to that
for lambda phi^4 QFT. In particular we prove that the massless KPZ equation
exhibits one-loop dynamical symmetry breaking (via an analog of the
Coleman-Weinberg mechanism) in 1 and 2 space dimensions, and that this
behaviour does not persist in 3 space dimensions.Comment: 13 pages, LaTeX 209, ReV_TeX 3.2, three *.eps figures, epsf.st
Design Validation of a Single Semiconductor-Based Marx-Generator Stage for Fast Step-Wise Arbitrary Output Waveforms
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