Jón Tómas Guðmundsson
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View article: Suppression of pair beam instabilities in a laboratory analogue of blazar pair cascades
Suppression of pair beam instabilities in a laboratory analogue of blazar pair cascades Open
The generation of dense electron–positron pair beams in the laboratory can enable direct tests of theoretical models of γ -ray bursts and active galactic nuclei. We have successfully achieved this using ultrarelativistic protons accelerate…
View article: An Online Data Analysis Framework for Accelerator-Based Physics Experiments
An Online Data Analysis Framework for Accelerator-Based Physics Experiments Open
A robust and flexible architecture capable of providing real-time analysis on diagnostic data is of crucial importance to physics experiments. In this paper, we present such an online framework, used in June 2025 as part of the HRMT-68 exp…
View article: Striations in electronegative capacitive chlorine discharges: effects of pressure, frequency, voltage and secondary electron emission
Striations in electronegative capacitive chlorine discharges: effects of pressure, frequency, voltage and secondary electron emission Open
Self organized striation structures have been observed in electronegative capacitive discharges under certain operating conditions, which include high electronegativity and an ion plasma frequency comparable to the driving frequency. In th…
View article: Role of sputtered atom and ion energy distribution in films deposited by physical vapor deposition: A molecular dynamics approach
Role of sputtered atom and ion energy distribution in films deposited by physical vapor deposition: A molecular dynamics approach Open
We present a comparative molecular dynamics simulation study of copper film growth between various physical vapor deposition (PVD) techniques: a constant energy neutral beam, thermal evaporation, dc magnetron sputtering, high-power impulse…
View article: Probing trade-off between critical size and velocity in cold-pray: An atomistic simulation
Probing trade-off between critical size and velocity in cold-pray: An atomistic simulation Open
The detailed mechanism of bonding in the cold spray process has remained elusive for both experimental and theoretical parties. Adiabatic shear instability and hydrodynamic plasticity models have been so far the most popular explanations. …
View article: Probing trade-off between critical size and velocity in cold-spray: An atomistic simulation
Probing trade-off between critical size and velocity in cold-spray: An atomistic simulation Open
The detailed mechanism of bonding in the cold spray process has remained elusive for both experimental and theoretical parties. Adiabatic shear instability and hydrodynamic plasticity models have been so far the most popular explanations. …
View article: The role of sputtered atom and ion energy distribution in films deposited by Physical Vapor Deposition: A molecular dynamics approach
The role of sputtered atom and ion energy distribution in films deposited by Physical Vapor Deposition: A molecular dynamics approach Open
We present a comparative study of copper film growth with a constant energy neutral beam, thermal evaporation, dc magnetron sputtering, high-power impulse magnetron sputtering (HiP-IMS), and bipolar HiPIMS, through molecular dynamics simul…
View article: High power impulse magnetron sputtering of a zirconium target
High power impulse magnetron sputtering of a zirconium target Open
High power impulse magnetron sputtering (HiPIMS) discharges with a zirconium target are studied experimentally and by applying the ionization region model (IRM). The measured ionized flux fraction lies in the range between 25% and 59% and …
View article: On working gas rarefaction in high power impulse magnetron sputtering
On working gas rarefaction in high power impulse magnetron sputtering Open
The ionization region model (IRM) is applied to explore working gas rarefaction in high power impulse magnetron sputtering discharges operated with graphite, aluminum, copper, titanium, zirconium, and tungsten targets. For all cases the wo…
View article: On the influence of electrode surfaces on the plasma chemistry of a capacitive chlorine discharge
On the influence of electrode surfaces on the plasma chemistry of a capacitive chlorine discharge Open
One-dimensional particle-in-cell/Monte Carlo collisional simulations are performed on capacitive chlorine discharges with 2.54 cm gap rf driven by a sinusoidal with voltage amplitude of 222 V at driving frequency of 13.56 MHz. The properti…
View article: Laboratory realization of relativistic pair-plasma beams
Laboratory realization of relativistic pair-plasma beams Open
Relativistic electron-positron (e±)plasmas are ubiquitous in extreme astrophysical environments such as black holes and neutron star magnetospheres, where accretion-powered jets and pulsar winds are expected to be enriched with such pair p…
View article: Laboratory realization of relativistic pair-plasma beams
Laboratory realization of relativistic pair-plasma beams Open
Relativistic electron-positron plasmas are ubiquitous in extreme astrophysical environments such as black holes and neutron star magnetospheres, where accretion-powered jets and pulsar winds are expected to be enriched with such pair plasm…
View article: Insights into the copper HiPIMS discharge: deposition rate and ionised flux fraction
Insights into the copper HiPIMS discharge: deposition rate and ionised flux fraction Open
The influence of pulse length, working gas pressure, and peak discharge current density on the deposition rate and ionised flux fraction in high power impulse magnetron sputtering discharges of copper is investigated experimentally using a…
View article: Influence of the magnetic field on the extension of the ionization region in high power impulse magnetron sputtering discharges
Influence of the magnetic field on the extension of the ionization region in high power impulse magnetron sputtering discharges Open
The high power impulse magnetron sputtering (HiPIMS) discharge brings about increased ionization of the sputtered atoms due to an increased electron density and efficient electron energization during the active period of the pulse. The ion…
View article: On the importance of excited state species in low pressure capacitively coupled plasma argon discharges
On the importance of excited state species in low pressure capacitively coupled plasma argon discharges Open
In the past three decades, first principles-based fully kinetic particle-in-cell Monte Carlo collision (PIC/MCC) simulations have been proven to be an important tool for the understanding of the physics of low pressure capacitive discharge…
View article: Angular distribution of titanium ions and neutrals in high-power impulse magnetron sputtering discharges
Angular distribution of titanium ions and neutrals in high-power impulse magnetron sputtering discharges Open
The angular dependence of the deposition rates due to ions and neutrals in high-power impulse magnetron sputtering (HiPIMS) discharges with a titanium target were determined experimentally using a magnetically shielded and charge-selective…
View article: Inductively-coupled plasma discharge for use in high-energy-density science experiments
Inductively-coupled plasma discharge for use in high-energy-density science experiments Open
Inductively-coupled plasma discharges are well-suited as plasma sources for experiments in fundamental high-energy density science, which require large volume and stable plasmas. For example, experiments studying particle beam-plasma insta…
View article: Epitaxial growth and characterization of (001) [NiFe/M]20 (M = Cu, CuPt and Pt) superlattices
Epitaxial growth and characterization of (001) [NiFe/M]20 (M = Cu, CuPt and Pt) superlattices Open
We present optimization of [(15 Å) Ni80Fe20/(5 Å) M]20 single crystal multilayers on (001) MgO substrates, with M being Cu, Cu50Pt50 and Pt. These superlattices were characterized by high resolution X-ray reflectivity (XRR) and diffraction…
View article: High power impulse magnetron sputtering of tungsten: a comparison of experimental and modelling results
High power impulse magnetron sputtering of tungsten: a comparison of experimental and modelling results Open
Here, we compare the ionization region model (IRM) against experimental measurements of particle densities and electron temperature in a high power impulse magnetron sputtering discharge with a tungsten target. The semi-empirical model pro…
View article: Epitaxial growth and characterization of (001) [NiFe/M]$_{20}$ (M = Cu, CuPt and Pt) superlattices
Epitaxial growth and characterization of (001) [NiFe/M]$_{20}$ (M = Cu, CuPt and Pt) superlattices Open
We present optimization of [(15 $\unicode{x212B}$) Ni$_{80}$Fe$_{20}$/(5 $\unicode{xC5}$) M]$_{20}$ single crystal multilayers on (001) MgO, with M being Cu, Cu$_{50}$Pt$_{50}$ and Pt. These superlattices were characterized by high-resolut…
View article: Target ion and neutral spread in high power impulse magnetron sputtering
Target ion and neutral spread in high power impulse magnetron sputtering Open
In magnetron sputtering, only a fraction of the sputtered target material leaving the ionization region is directed toward the substrate. This fraction may be different for ions and neutrals of the target material as the neutrals and ions …
View article: Foundations of physical vapor deposition with plasma assistance
Foundations of physical vapor deposition with plasma assistance Open
Physical vapor deposition (PVD) refers to the removal of atoms from a solid or a liquid by physical means, followed by deposition of those atoms on a nearby surface to form a thin film or coating. Various approaches and techniques are appl…
View article: Operating modes and target erosion in high power impulse magnetron sputtering
Operating modes and target erosion in high power impulse magnetron sputtering Open
Magnetron sputtering combines a glow discharge with sputtering from a target that simultaneously serves as a cathode for the discharge. The electrons of the discharge are confined between overarching magnetic field lines and the negatively…
View article: Modeling of high power impulse magnetron sputtering discharges with tungsten target
Modeling of high power impulse magnetron sputtering discharges with tungsten target Open
The ionization region model (IRM) is applied to model a high power impulse magnetron sputtering discharge with a tungsten target. The IRM gives the temporal variation of the various species and the average electron energy, as well as inter…
View article: Ionization region model of high power impulse magnetron sputtering of copper
Ionization region model of high power impulse magnetron sputtering of copper Open
The ionization region model (IRM) is applied to model high power impulse magnetron sputtering (HiPIMS) discharges with a Cu target. We apply the model to three discharges that were experimentally explored in the past, or applied to deposit…
View article: On the population density of the argon excited levels in a high power impulse magnetron sputtering discharge
On the population density of the argon excited levels in a high power impulse magnetron sputtering discharge Open
Population densities of excited states of argon atoms in a high power impulse magnetron sputtering (HiPIMS) discharge are examined using a global discharge model and a collisional-radiative model. Here, the ionization region model (IRM) an…
View article: Surface effects in a capacitive argon discharge in the intermediate pressure regime
Surface effects in a capacitive argon discharge in the intermediate pressure regime Open
One-dimensional particle-in-cell/Monte Carlo collisional simulations are performed on a capacitive 2.54 cm gap, 1.6 Torr argon discharge driven by a sinusoidal rf current density amplitude of 50 A m −2 at 13.56 MHz. The excited argon state…
View article: Modeling of high power impulse magnetron sputtering discharges with graphite target
Modeling of high power impulse magnetron sputtering discharges with graphite target Open
The ionization region model (IRM) is applied to model a high power impulse magnetron sputtering discharge in argon with a graphite target. Using the IRM, the temporal variation of the various species and the average electron energy, as wel…