Response to ''Comment on 'Scalings for radiation from plasma bubbles''' [Phys. Plasmas 18, 034701 (2011)]
- Centre for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109 (United States)
In the preceding Comment, Corde, Stordeur, and Malka claim that the trapping threshold derived in my recent paper is incorrect. Their principal argument is that the elliptical orbits I used are not exact solutions of the equation of motion in the fields of the bubble. The original paper never claimed this--rather I claimed that the use of elliptical orbits was a reasonable approximation, which I based on observations from particle-in-cell simulations. Integration of the equation of motion for analytical expressions for idealized bubble fields (either analytically [I. Kostyukov, E. Nerush, A. Pukhov, and V. Seredov, Phys. Rev. Lett. 103, 175003 (2009)] or numerically [S. Corde, A. Stordeur, and V. Malka, ''Comment on 'Scalings for radiation from plasma bubbles,' '' Phys. Plasmas 18, 034701 (2011)]) produces a trapping threshold wholly inconsistent with experiments and full particle-in-cell (PIC) simulations (e.g., requiring an estimated laser intensity of a{sub 0{approx}}30 for n{sub e{approx}}10{sup 19} cm{sup -3}). The inconsistency in the particle trajectories between PIC and the numeric model used by the comment authors arises due to the fact that the analytical fields are only approximately true for ''real'' plasma bubbles, and lack certain key features of the field structure. Two possible methods of resolution to this inconsistency are either to find ever more complicated but accurate models for the bubble fields or to find approximate solutions to the equations of motion that capture the essential features of the self-consistent electron trajectories. The latter, heuristic approach used in my recent paper produced a threshold that is better matched to experimental observations. In this reply, I will also revisit the problem and examine the relationship between bubble radius and electron momentum at the point of trapping without reference to a particular trajectory.
- OSTI ID:
- 21537347
- Journal Information:
- Physics of Plasmas, Vol. 18, Issue 3; Other Information: DOI: 10.1063/1.3566013; (c) 2011 American Institute of Physics; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
43 PARTICLE ACCELERATORS
BUBBLES
ELECTRONS
EQUATIONS OF MOTION
PLASMA
PLASMA SHEATH
PLASMA SIMULATION
SCALING
TRAPPING
DIFFERENTIAL EQUATIONS
ELEMENTARY PARTICLES
EQUATIONS
FERMIONS
LEPTONS
PARTIAL DIFFERENTIAL EQUATIONS
SIMULATION