Skew Quadrupole Effect of Laser Plasma Electron Beam Transport

Quadrupole-induced resonant-particle transport in a pure electron plasma.

Small transverse magnetic quadrupole fields sharply degrade the confinement of non-neutral plasmas held in Malmberg-Penning traps. For example, a quadrupole magnetic field of only 0.02 G/cm doubles the diffusion rate in a trap with a 100 G axial magnetic field. Larger quadrupole fields noticeably change the shape of the plasma. The transport is greatest at an orbital resonance. These results ca...

The beam breakup instability in quadrupole and solenoidal electron-beam transport systems

Dispersion relations are derived to determine the growth rate, dominant wavelength, and group velocity of disturbances caused by the beam breakup instability. Considerations include weak and strong focusing, x-y coupling in solenoidal transport, the spacing of accelerator cavities, and periodically pulsed beams. Beam breakup growth is minimum when the cavity spacing equals an integral number of...

Ultrafast electron beam imaging of femtosecond laser-induced plasma dynamics

Plasma dynamics in the early stage of laser ablation of a copper target are investigated in real time by making ultrafast electron shadow images and electron deflectometry measurements. These complementary techniques provide both a global view and a local perspective of the associated transient electric field and charge expansion dynamics. The results reveal that the charge cloud above the targ...

Diagnostics of Laser Initiated Plasma Channels for Ion Beam Transport

Laser initiated, free standing discharge channels offer many attractive advantages for the transport and focusing of intense ion beams [1, 2]. Discharge plasmas can neutralize both current and space charge of such beams, while the azimuthal magnetic field provides strong focusing all the way through the channel. Experiments at GSI have produced 50 cm long stable plasma channels with peak curren...

Effect of beam quality on the free-electron laser.