Transverse two-stream instability in the presence of strong species-species and image forces

Abstract

The theory of cohe.·C'ent transverse oscillations of u;"e) particle species is extended to include strong species-species and linage forces.It is ShOWl that in g~neral the species-speci.es force can conside:C3.bly alter the instability threshold. Conversely, it is shC>·~Tn that the limit on the perfor:J!e,~ce of an cJ.2ctron ring accelerator im'po~ed by the re~uireQent of stable ion electron oscillations, is not sigaificantly Yicr~sup:r:)ytc:2 by the U.S . .L;tor:.ic EC2r w CC':tG:~L:sion.

Kinetic description of electron-proton instability in high-intensity proton linacs and storage rings based on the Vlasov-Maxwell equations

“…For example, a background population of electrons can result locally when an H 2 beam is injected through a stripper foil into a proton storage ring or when energetic ions strike the chamber wall. When a second charge component is present, it has been recognized for many years, both in theoretical studies and in experimental observations [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42], that the relative streaming motion of the high-intensity beam particles through the background charge species provides the free energy to drive the classical two-stream instability [43 -45], appropriately modified to include the effects of dc space charge, relativistic kinematics, presence of a conducting wall, etc. For electrons interacting with a proton beam, as in the Proton Storage Ring (PSR), this instability is usually referred to as the electron-proton ͑e-p͒ instability [31][32][33][34][35], although a similar instability also exists for other ion species, including (for example) electron-ion interactions in electron storage rings [36][37][38][39][40][41].…”

Three-dimensional multispecies nonlinear perturbative particle simulations of collective processes in intense particle beams

“…In a high-intensity ion beam, the surface mode described above can be destabilized by the presence of a background electron population [12][13][14][15][16][17][18]. This instability is basically of the two-stream type and is strongest when the ions are relatively cold in the propagation direction.…”

“…For example, a background population of electrons can result by secondary emission when energetic beam ions strike the chamber wall, or through ionization of background neutral gas by the beam ions. When a second charge component is present, it has been recognized for many years, both in theoretical studies and in experimental observations [12][13][14][15][16][17][18][19][20][21], that the relative streaming motion of the high-intensity beam particles through the background charge species provides the free energy to drive the classical two-stream instability [22], appropriately modified to include the effects of dc space charge, relativistic kinematics, presence of a conducting wall, etc. A well-documented example is the electron-proton (e-p) instability observed in the Proton Storage Ring (PSR) [17,18], although a similar instability also exists for other ion species including (for example) electron-ion interactions in electron storage rings [19 -21].…”

“…The present paper reports recent advances in applying the df formalism to investigate nonlinear collective processes in intense charged particle beams. The BEST ( beam equilibrium, stability, and transport) code [25] described here is a newly developed 3D multispecies nonlinear perturbative particle simulation code, which can be applied to a wide range of important collective processes in intense beams, such as the electron-ion two-stream instability [12][13][14][15][16][17][18] and the periodically focused beam propagation [11]. While several features of the 3D BEST code are summarized in Ref.…”

3D simulation studies of the two-stream instability in intense particle beams based on the Vlasov-Maxwell equations

“…In periodic focusing accelerators and transport systems [1][2][3][4], when a second charge component is present, it has been recognized for many years, both in theoretical studies and in experimental observations [5][6][7][8][9][10][11][12][13][14][15][16][17][18], that the relative streaming motion of the high-intensity beam particles through a background charge species provides the free energy to drive the classical two-stream instability, appropriately modified to include the effects of dc space charge, relativistic kinematics, presence of a conducting wall, etc. A background population of electrons can result by secondary emission when energetic beam ions strike the chamber wall, or through ionization of background neutral gas by the beam ions.…”