Working Group specified - Invited Oral in Working
Victor: Recent results on high energy and
high quality electron beams from relativistic laser-plasma
interaction with ultra short laser pulse.
| We report on recent
results of electron acceleration by ultrashort,
high repetition rate laser systems. High energy
and very high quality electron beams have been measured
in a very specific parameter regime. The most remarkable
characteristic of these beams is their high spatial
quality: the beam is nearly a perfect Gaussian very
collimated with a divergence less than 10 mrad.
In this regime, the electron beam pointing, as well
as its stability, (a critical issue for applications)
is also very good. Electron energies extend to beyond
200 MeV limited by our detection device. The full
energy distributions measured in a single shot show
very interested non monotonic feature. Typical charges
in a 10 % energy bandwidth of 100, 50 and 10 pC
have been measured respectively at 20, 50 and 100
MeV. These high performances were only achieved
when a fully compressed (30-40 fs), 1.3 J laser
pulse was interacting with a plasma with electron
density between 0.7×1018 cm?3 and 2.5×1019
cm-3. The role of laser plasma approach concerning
high energy physics will be discussed on the basis
of the presented results.
University of Maryland Electron Ring: a model recirculator
for intense-beam physics research
| The University of
Maryland Electron Ring (UMER), designed for transport
studies of space-charge dominated beams in a strong
focusing lattice, is nearing completion. Low energy,
high intensity electron beams provide an excellent
model system for experimental studies with relevance
to all areas that require high quality, intense
charged-particle beams. In addition, UMER constitutes
an important tool for benchmarking of computer codes.
When completed, the UMER lattice will consist of
36 alternating-focusing (FODO) periods over an 11.5-m
circumference. Current studies in UMER over about
2/3 of the ring include beam-envelope matching,
halo formation, unsymmetrical focusing, and longitudinal
dynamics (beam bunch erosion and wave propagation.)
Near future, multi-turn operation of the ring will
allow us to address important additional issues
such as resonance-traversal, energy spread and others.
The main diagnostics are phosphor screens and capacitive
beam position monitors placed at the center of each
20-degree bending section. In addition, pepper-pot
and slit-wire emittance meters are in operation.
The range of beam currents used correspond to space
charge tune depressions from 0.2 to 0.8, which is
unprecedented for a circular machine.
Smirnova: Photonic Band Gap structures for
| A photonic band gap
(PBG) structure is a one-, two- or three-dimensionalperiodic
metallic and/or dielectric system (for example,
of rods), whichacts like a filter, reflecting rf
fields in some frequency range andallowing rf fields
at other frequencies to transmit through. PBG structureshave
many promising applications in active and passive
devices at millimeterwave and higher frequencies.
Metal PBG structures can be employed at X andKu-band
accelerators to suppress wakefields whenever dielectric
PBGstructures are attractive at higher frequency
for construction of low-losslaser-driven accelerators.
For both applications two-dimensional (2D) PBGstructures
are of main interest. In this talk I present a review
oftheoretical studies and computer modeling of 2D
metal and dielectricstructures. Also world-wide
experimental efforts on constructing and testingmetal
and dielectric PBG accelerators and microwave devices