12 research outputs found
Novel reaction force for ultra-relativistic dynamics of a classical point charge
The problem of the electromagnetic radiation of an accelerated charged
particle is one of the most controversial issues in Physics since the beginning
of the last century, representing one of the most popular unsolved problems of
the Modern Physics. Different equations of motion have been proposed throughout
history for a point charge including the electromagnetic radiation emitted, but
all these expressions show some limitations. An equation based on the principle
of conservation of energy is proposed in this work for the ultra-relativistic
motion. Different examples are analyzed showing that the energy lost by the
charge agrees with the Li\'enard formula. This proposed equation has been
compared with the Landau-Lifshitz equation obtaining a good agreement in the
range of application of the Landau-Lifshitz formula.Comment: 9 pages, 10 figure
Numerical study of dark current dynamics in a high-gradient backward travelling wave accelerating cavity using the electromagnetic simulation software CST studio.
High-Gradient accelerating cavities are one of the main research lines in the development of
compact linear colliders. However, the operation of such cavities is currently limited by nonlinear
effects that are intensified at high electric fields, such as dark currents and radiation
emission or RF breakdowns.
A new normal-conducting High-Gradient S-band Backward Travelling Wave accelerating
cavity for medical application (v=0.38c) designed and constructed at Conseil Européen pour la
Recherche NuclĂ©aire (CERN) is being tested at Instituto de FĂsica Corpuscular (IFIC) High Power
RF Laboratory. The objective consists of studying its viability in the development of compact
linear accelerators for hadrontherapy treatments in hospitals.
Due to the high surface electric field in the cavity, electrons are emitted following Fowler-
Nordheim equation, also known as dark currents. The emission and dynamic of these
electrons are of fundamental importance on different phenomena such as RF Breakdowns or
radiation dose emission.
In this work, 3D electromagnetic numerical simulations have been performed using the
computer simulation technology software CST Studio Suite. Then, the resulting EM field maps
are used to study the emission and electron dynamics inside the cavity. The simulation results
are compared with experimental data and first conclusions discussed
Relativistic particle motion of a charge including the radiation reaction
The problem of the electromagnetic radiation of an accelerated charged particle is one of the
most controversial issues in Physics since the beginning of the last century representing one of
the most popular unsolved problems of the Modern Physics. Different equations of motion for
a point charge including the electromagnetic radiation emitted have been proposed throughout
history, but all these expressions show some limitations. An equation based on the principle of
conservation of energy is proposed for the ultra-relativistic motion. Different examples are
analyzed showing that the energy lost by the charge agrees with the relativistic generalization
of the Larmor formula. This proposed equation has been compared with the Landau-Lifshitz
equation obtaining a good agreement in the range of application of the Landau-Lifshitz formula.
Finally, it is discussed a possible variation of the typical relativistic particle integrators (e.g. Boris,
Vay or Higuera-Cary methods) in order to include the radiation reaction
Study of the RF pulse heating phenomenon in high gradient accelerating devices by means of analytical approximations
The main objective of this work is to present a
simple method, based on analytical expressions, for obtaining
a quick approximation of the temperature rise due to the Joule
effect inside the metallic walls of an RF accelerating device. This
proposal relies on solving the 1D heat-transfer equation for a
thick wall, where the heat sources inside the wall are the ohmic
losses produced by the RF electromagnetic fields penetrating
the metal with finite electrical conductivity. Furthermore, it is
discussed how the theoretical expressions of this method can be
applied to obtain an approximation to the temperature increase
in realistic 3D RF accelerating structures, taking as an example
the cavity of an RF electron gun. These theoretical results have
been benchmarked with numerical simulations carried out with
commercial finite-element method codes, finding good agreement
among them
Two-dimensional simulation of the electron transport in a photomultiplier tube
Photomultiplier tubes are widely used in experimental physics because they convert small light
signals into a measurable electric current. Although their working principle is well known, it is
very difficult to find simulations of the electron transport in these devices. For this reason, the
electron transport in the Hamamatsu R13408-100 photomultiplier tube has been simulated in
2D. The software SUPERFISH is used for calculating the electrostatic fields and the Boris method
for the effective electron dynamics. The secondary electron emission in the dynodes is
implemented using an effective electron model and the modified Vaughan’s model. Some
figures of merit for photomultiplier tubes (e.g. the gain, the electron transit time or the transit
time spread) in function of the supply voltage and an external magnetic field have been studied
obtaining a good qualitative accordance with the Hamamatsu datasheet. In further studies, we
are going to compare our simulations with experimental measurements
The 2024 Europe report of the Lancet Countdown on health and climate change: unprecedented warming demands unprecedented action
Record-breaking temperatures were recorded across the globe in 2023. Without climate action, adverse climate-related health impacts are expected to worsen worldwide, affecting billions of people. Temperatures in Europe are warming at twice the rate of the global average, threatening the health of populations across the continent and leading to unnecessary loss of life. The Lancet Countdown in Europe was established in 2021, to assess the health profile of climate change aiming to stimulate European social and political will to implement rapid health-responsive climate mitigation and adaptation actions. In 2022, the collaboration published its indicator report, tracking progress on health and climate change via 33 indicators and across five domains.
This new report tracks 42 indicators highlighting the negative impacts of climate change on human health, the delayed climate action of European countries, and the missed opportunities to protect or improve health with health-responsive climate action. The methods behind indicators presented in the 2022 report have been improved, and nine new indicators have been added, covering leishmaniasis, ticks, food security, health-care emissions, production and consumption-based emissions, clean energy investment, and scientific, political, and media engagement with climate and health. Considering that negative climate-related health impacts and the responsibility for climate change are not equal at the regional and global levels, this report also endeavours to reflect on aspects of inequality and justice by highlighting at-risk groups within Europe and Europe's responsibility for the climate crisis
X-band RF photoinjector design for the CompactLight project
RF photoinjectors have been under development for several decades to provide the high-brightness electron beams required for X-ray Free Electron Lasers. This paper proposes a photoinjector design that meets the Horizon 2020 CompactLight design study requirements. It consists of a 5.6-cell, X-band (12 GHz) RF gun, an emittance-compensating solenoid and two X-band traveling-wave structures that accelerate the beam out of the space-charge-dominated regime. The RF gun is intended to operate with a cathode gradient of 200 MV/m, and the TW structures at a gradient of 65 MV/m. The shape of the gun cavity cells was optimized to reduce the peak electric surface field. An assessment of the gun RF breakdown likelihood is presented as is a multipacting analysis for the gun coaxial coupler. RF pulse heating on the gun inner surfaces is also evaluated and beam dynamics simulations of the 100MeV photoinjector are summarized
Spectrum/Space Switching and Multi-Terabit Transmission in Agile Optical Metro Networks
An SDN-enabled modular photonic system architecture, including VCSEL-based bandwidth/bitrate variable transceivers, for multi-terabit capacity transmission and agile spectrum/space switching in optical metro networks is presented, providing the proposed technological solutions, programmability aspects and preliminary assessment
Spectrum/space switching and multi-terabit transmission in agile optical metro networks
\u3cp\u3eAn SDN-enabled modular photonic system architecture, including VCSEL-based bandwidth/bitrate variable transceivers, for multi-terabit capacity transmission and agile spectrum/space switching in optical metro networks is presented, providing the proposed technological solutions, programmability aspects and preliminary assessment.\u3c/p\u3
The 2022 Europe report of the Lancet Countdown on health and climate change : towards a climate resilient future
In the past few decades, major public health advances have happened in Europe, with drastic decreases in premature mortality and a life expectancy increase of almost 9 years since 1980. European countries have some of the best health-care systems in the world. However, Europe is challenged with unprecedented and overlapping crises that are detrimental to human health and livelihoods and threaten adaptive capacity, including the COVID-19 pandemic, the Russian invasion of Ukraine, the fastest-growing migrant crisis since World War 2, population displacement, environmental degradation, and deepening inequalities. Compared with pre-industrial times, the mean average European surface air temperature increase has been almost 1°C higher than the average global temperature increase, and 2022 was the hottest European summer on record. As the world's third largest economy and a major contributor to global cumulative greenhouse gas emissions, Europe is a key stakeholder in the world's response to climate change and has a global responsibility and opportunity to lead the transition to becoming a low-carbon economy and a healthier, more resilient society. The Lancet Countdown in Europe is a collaboration of 44 leading researchers, established to monitor the links between health and climate change in Europe and to support a robust, evidence-informed response to protect human health. Mirroring the Global Lancet Countdown, this report monitors the health effects of climate change and the health co-benefits of climate action in Europe. Indicators will be updated on an annual basis and new indicators will be incorporated to provide a broad overview to help guide policies to create a more climate-resilient future