Downramp-assisted underdense photocathode electron bunch generation in plasma wakefield accelerators

It is shown that the requirements for high quality electron bunch generation and trapping from an underdense photocathode in plasma wakefield accelerators can be substantially relaxed through localizing it on a plasma density downramp. This depresses the phase velocity of the accelerating electric field until the generated electrons are in phase, allowing for trapping in shallow trapping potentials. As a consequence the underdense photocathode technique is applicable by a much larger number of accelerator facilities. Furthermore, dark current generation is effectively suppressed.Comment: 4 pages, 3 figure

Plasma accelerator-based ultrabright x-ray beams from ultrabright electron beams

We provide a pathway to compact ultrabright light sources, based on ultrabright, high energy electron beams emerging from a combination of plasma Wakefield acceleration and plasma photocathodes. While plasma acceleration is known to produce accelerating fields three or four orders of magnitude larger than conventional accelerators, the plasma photocathode allows production of electron beams three or four orders of magnitude brighter than conventional, and thus is suitable to unleash the full potential of plasma accelerators. In particular, this is the case for various types of light sources, which profit enormously from an increased electron beam brightness. Building on the recent first experimental demonstration of the plasma photocathode, in this work we discuss the prospects of plasma photocathodes for key photon source approaches such as x-ray free-electron lasers, betatron radiation, ion-channel lasers and inverse Compton scattering

Characterization of laser-driven single and double electron bunches with a permanent magnet quadrupole triplet and pepper-pot mask

Electron beams from laser-plasma wakefield accelerators have low transverse emittance, comparable to those from conventional radio frequency accelerators, which highlights their potential for applications, many of which will require the use of quadrupole magnets for optimal electron beam transport. We report on characterizing electron bunches where double bunches are observed under certain conditions. In particular, we present pepper-pot measurements of the transverse emittance of 120-200 MeV laser wakefield electron bunches after propagation through a triplet of permanent quadrupole magnets. It is shown that the normalized emittance at source can be as low as 1 π mm mrad (resolution limited), growing by about five times after propagation through the quadrupoles due to beam energy spread. The inherent energy-dependence of the magnets also enables detection of double electron bunches that could otherwise remain unresolved, providing insight into the self-injection of multiple bunches. The combination of quadrupoles and pepper-pot, in addition, acts as a diagnostic for the alignment of the magnetic triplet

The SCAPA LWFA beamline

The Scottish Centre for the Application of Plasma based Accelerators situated at the University of Strathclyde in Glasgow, UK, is coming online. It comprises three radiation shielded concrete bunkers housing a total of seven beamlines and interaction chambers, each driven by one of a pair of high power Ti sapphire laser systems a 350 TW and a 40 TW

Angled laser triggered electron injection in the electron driven plasma wakefield acceleration scheme : a case study in a pursuit to increase tolerance levels, based on FACET II driver parameters.

Co-axial laser triggered injection of electrons in PWFA can produce high quality witness bunches. In this study, angled injection was examined in a pursuit to increase the tolerance levels of synchronization and experimental misalignments while maintaining the high quality of the witness bunches

PEMBINAAN NILAI-NILAI KARAKTER KRISTIANI MELALUI KREATIVITAS PAJANGAN BINGKAI DENGAN PEMBERDAYAAN KARDUS BEKAS DI SEKOLAH DASAR KRISTEN TEOLOGI SAHABAT BATAM

Pada usia anak umur 8-9 tahun tentunya anak-anak akan diberikan pengarahan dan bimbingan pada saat pembelajaran, agar anak-anak bisa mengerti dan mengenal nilai-nilai karakter Kristiani dalam kehidupan mereka terkhususnya di Sekolah Dasar Teologi Kristen Sahabat Batam. Anak-anak yang berusia 8-9 tahun ini perlu adanya bimbingan dari pihak guru supaya mereka bisa menerapkan nilai-nilai karakter Kristiani di sekolah. Kegiatan Pengabdian Kepada Masyarakat ini dilakukan sebagai bentuk kepedulian kepada anak-anak usia 8-9 tahun di Sekolah Dasar Teologi Kristen Sahabat Batam yang memberikan penguatan bagi Kognitif mereka melalui Kreativitas Pajangan Bingkai dengan  Pemberdayaan kardus bekas serta memberikan alat-alat untuk membuat pajangan bingkai supaya mereka semangat untuk mengerjakan kreativitas tersebut. Kegiatan yang dilakukan dengan menggunakan metode kardus bekas dan memberikan cara-cara bagaimana anak-anak bisa membuat pajangan bingkai dari kardus bekas. Melalui kreativitas pajangan bingkai ini bisa memberikan anak-anak lebih mudah untuk membuat kreativitas dan bisa lebih semangat ketika belajar. Dari pengamatan yang dilakukan oleh tim PKM ditemukan bahwa anak-anak sangat antusias dalam mengikuti pembelajaran dari awal sampai akhir. Setelah melakukan kegiatan ini anak-anak bisa menunjukkan hasil dari kreativitas pajangan bingkai mereka dan bisa lebih mengerti dalam hal nilai-nilai Karakter Kristiani

Design of a double dipole electron spectrometer

With the increase of laser power at facilities reaching petawatt-level, there is a need for accurate electron beam diagnostics of the laser wakefield accelerator (LWFA), which are becoming important tools for a wide range of applications including high field physics. Electrons in the range of several 10 0s of GeV are expected at these power levels. Precise diagnostic systems are required to enable applications such as advanced radiation sources. Accurate measurement of the energy spread of electron beams will help pave the way towards LWFA based free-electron lasers and plasma based coherent radiation sources. We propose an innovative double dipole spectrometer suitable for characterizing bunches produced using a petawatt class laser

Electron beam manipulation, injection and acceleration in plasma wakefield accelerators by optically generated plasma density spikes

We discuss considerations regarding a novel and robust scheme for optically triggered electron bunch generation in plasma wakefield accelerators [1]. In this technique, a transversely propagating focused laser pulse ignites a quasi-stationary plasma column before the arrival of the plasma wake. This localized plasma density enhancement or optical "plasma torch" distorts the blowout during the arrival of the electron drive bunch and modifies the electron trajectories, resulting in controlled injection. By changing the gas density, and the laser pulse parameters such as beam waist and intensity, and by moving the focal point of the laser pulse, the shape of the plasma torch, and therefore the generated trailing beam, can be tuned easily. The proposed method is much more flexible and faster in generating gas density transitions when compared to hydrodynamics-based methods, and it accommodates experimentalists needs as it is a purely optical process and straightforward to implement

Plasma-photonic spatiotemporal synchronization of relativistic electron and laser beams

Modern particle accelerators and their applications increasingly rely on precisely coordinated interactions of intense charged particle and laser beams. Femtosecond-scale synchronization alongside micrometre-scale spatial precision are essential e.g. for pump-probe experiments, seeding and diagnostics of advanced light sources and for plasma-based accelerators. State-of-the-art temporal or spatial diagnostics typically operate with low-intensity beams to avoid material damage at high intensity. As such, we present a plasma-based approach, which allows measurement of both temporal and spatial overlap of high-intensity beams directly at their interaction point. It exploits amplification of plasma afterglow arising from the passage of an electron beam through a laser-generated plasma filament. The corresponding photon yield carries the spatiotemporal signature of the femtosecond-scale dynamics, yet can be observed as a visible light signal on microsecond-millimetre scales

Electron bunch generation from a plasma photocathode

Plasma waves generated in the wake of intense, relativistic laser or particle beams can accelerate electron bunches to giga-electronvolt (GeV) energies in centimetre-scale distances. This allows the realization of compact accelerators having emerging applications, ranging from modern light sources such as the free-electron laser (FEL) to energy frontier lepton colliders. In a plasma wakefield accelerator, such multi-gigavolt-per-metre (GV m$^{-1}$) wakefields can accelerate witness electron bunches that are either externally injected or captured from the background plasma. Here we demonstrate optically triggered injection and acceleration of electron bunches, generated in a multi-component hydrogen and helium plasma employing a spatially aligned and synchronized laser pulse. This ''plasma photocathode'' decouples injection from wake excitation by liberating tunnel-ionized helium electrons directly inside the plasma cavity, where these cold electrons are then rapidly boosted to relativistic velocities. The injection regime can be accessed via optical density down-ramp injection, is highly tunable and paves the way to generation of electron beams with unprecedented low transverse emittance, high current and 6D-brightness. This experimental path opens numerous prospects for transformative plasma wakefield accelerator applications based on ultra-high brightness beams