IPAC2011 - List of Authors (Pakter, R.)

Paper	Title	Page
MOPS023	An Analytical Lagrangian Model for Analyzing Temperature Effects in Intense Non-neutral Beams*	646
	E.G. Souza, A. Endler, R. Pakter, F.B. Rizzato IF-UFRGS, Porto Alegre, Brazil
	High-intensity charged-particle beams are used in several areas of physics. We can mention as an illustration, high-energy colliders, particle accelerators and vacuum electron devices. In all cases quoted above, the beam lose particles in the acceleration process, between its production to its final destination. These ejected particles, generally, produce a surrounding structure around the beam core, called halo. This undesirable structure is seen in simulation as well as in actual linacs, and its formation has been one of the main sources of energy loss in the acceleration devices. For this reason, the need for an advance in understand the mechanism that produce the halo becomes necessary. In view of the whole problem, we contruct a 1D Lagrangian warm-fluid model for describe the behavior of inhomogeneous charged-particle beam in solenoidal focusing magnetic field. The equations of motion are derived for an adiabatic process with a state equation originated from the ideal gas law. In the end, the model is compared with self-consistent simulation and is used to explain emittance growth and jets of particle, even when the system is out of equilibrium.

MOPS042	One-Dimensional Adiabatic Child-Langmuir Flow	694
	C. Chen MIT, Cambridge, Massachusetts, USA R. Pakter, F.B. Rizzato IF-UFRGS, Porto Alegre, Brazil
	Funding: Research supported in part by US Department of Energy, Grant No. DE-FG02-95ER40919, CNPq, FAPERGS, INCTFCx of Brazil, and US Air Force Office of Scientific Research, Grant No. FA9550-09-1-0283. A theory is presented that describes steady-state one-dimensional Child-Langmuir flow at a self-consistent finite temperature distribution. In particular, warm-fluid equations and adiabatic equation of state are used to derive the self-consistent Poisson equation. The profiles of the charged-particle density, the velocity, the electrostatic potential, the pressure and the temperature are computed. Results are compared with self-consistent simulations.

WEPZ021	Self-Consistent Dynamics of Electromagnetic Pulses and Wakefields in Laser-Plasma Interactions	2811
	A. Bonatto, R. Pakter, F.B. Rizzato IF-UFRGS, Porto Alegre, Brazil
	In the present work we study the stability of laser pulses propagating in a cold relativistic plasma, which can be of interest for particle acceleration schemes. After obtaining a Lagrangian density from the one-dimensional equations for the laser pulse envelope and the plasma electron density, we define a trial function and apply the variational approach in order to obtain an analytical model which allows us to calculate an effective potential for the pulse width. Using this procedure, we analyze the stability of narrow and large laser pulses and then compare its results with numerical solutions for the envelope and density equations.

Paper

Title

Page

An Analytical Lagrangian Model for Analyzing Temperature Effects in Intense Non-neutral Beams*

646

E.G. Souza, A. Endler, R. Pakter, F.B. Rizzato
IF-UFRGS, Porto Alegre, Brazil

High-intensity charged-particle beams are used in several areas of physics. We can mention as an illustration, high-energy colliders, particle accelerators and vacuum electron devices. In all cases quoted above, the beam lose particles in the acceleration process, between its production to its final destination. These ejected particles, generally, produce a surrounding structure around the beam core, called halo. This undesirable structure is seen in simulation as well as in actual linacs, and its formation has been one of the main sources of energy loss in the acceleration devices. For this reason, the need for an advance in understand the mechanism that produce the halo becomes necessary. In view of the whole problem, we contruct a 1D Lagrangian warm-fluid model for describe the behavior of inhomogeneous charged-particle beam in solenoidal focusing magnetic field. The equations of motion are derived for an adiabatic process with a state equation originated from the ideal gas law. In the end, the model is compared with self-consistent simulation and is used to explain emittance growth and jets of particle, even when the system is out of equilibrium.

MOPS042

One-Dimensional Adiabatic Child-Langmuir Flow

694

C. Chen
MIT, Cambridge, Massachusetts, USA
R. Pakter, F.B. Rizzato
IF-UFRGS, Porto Alegre, Brazil

Funding: Research supported in part by US Department of Energy, Grant No. DE-FG02-95ER40919, CNPq, FAPERGS, INCTFCx of Brazil, and US Air Force Office of Scientific Research, Grant No. FA9550-09-1-0283.
A theory is presented that describes steady-state one-dimensional Child-Langmuir flow at a self-consistent finite temperature distribution. In particular, warm-fluid equations and adiabatic equation of state are used to derive the self-consistent Poisson equation. The profiles of the charged-particle density, the velocity, the electrostatic potential, the pressure and the temperature are computed. Results are compared with self-consistent simulations.

WEPZ021

Self-Consistent Dynamics of Electromagnetic Pulses and Wakefields in Laser-Plasma Interactions

2811

A. Bonatto, R. Pakter, F.B. Rizzato
IF-UFRGS, Porto Alegre, Brazil

In the present work we study the stability of laser pulses propagating in a cold relativistic plasma, which can be of interest for particle acceleration schemes. After obtaining a Lagrangian density from the one-dimensional equations for the laser pulse envelope and the plasma electron density, we define a trial function and apply the variational approach in order to obtain an analytical model which allows us to calculate an effective potential for the pulse width. Using this procedure, we analyze the stability of narrow and large laser pulses and then compare its results with numerical solutions for the envelope and density equations.