Kevin Verhaegh
Ecole Polytechnique Federale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), Guest PhD researcher
In order to obtain net power from a tokamak, the tokamak has to be made bigger than current facilities – which is partly why ITER is much larger than current tokamaks. One challenging aspect which arises in this case is that the heat loads on the materials facing the plasma become so large that no materials exist which can handle such a heat load. Therefore researching techniques to lower the heat load at the plasma facing components (commonly referred to as the divertor - a separate region where the plasma is “diverted” to and touches the plasma facing components) while maintaining a high performance in the core is essential for future tokamaks.
After completing my MScs in Science and Technology of Nuclear fusion and Applied Physics - both at Eindhoven University of Technology in the Netherlands - I started my PhD at the University of York under supervision of Prof. Bruce Lipschultz (University of York) and Dr. Holger Remeirdes (EPFL – Lausanne). During my PhD I am based at TCV - a tokamak based at EPFL, Lausanne, Switzerland. A unique feature of TCV is that there is a lot of freedom to “shape” the plasma, which can potentially lead to lower heat loads. My job at TCV is to look at the light radiated by the plasma near the plasma facing components with a spectrometer. By doing so, we can deduce the plasma parameters at the divertor. With these parameters we can work on a better understanding of how shaping the plasma can affect the heat load.
Previously, I’ve done a double master program in Fusion and Applied Physics at Eindhoven University of Technology. The thing that attracts me about fusion is its extreme diversity. It is extremely international (I’ve had the opportunity to both do research at JET in the UK and F4E in Barcelona). It is also diverse in disciplines – physics, mathematics and computer science (modelling), engineering (both mechanical and electrical) – all coming together for one purpose: achieving fusion on earth, mainly for the production of energy.
As my graduation project (in cooperation with the Coherence Quantum Technology (CQT) group at applied physics), I’m studying the interaction of nano-clusters with ultrashort, intense laser pulses in order to accelerate ions to induce fusion reactions: generating a neutron pulse. By having a better understanding of this process theoretically it is possible to tailor the interaction in such a way that an ultrashort neutron pulse can be generated. Ultrashort neutron pulses are a novel concept and show great promise in material science and bioresearch.
Supervisors: Bruce Lipschultz (York), Holger Reimerdes (EPFL), Basil Duval (EPFL), Niek Lopes Cardozo (TU/e), and Seth Brussaard (TU/e)
After completing my MScs in Science and Technology of Nuclear fusion and Applied Physics - both at Eindhoven University of Technology in the Netherlands - I started my PhD at the University of York under supervision of Prof. Bruce Lipschultz (University of York) and Dr. Holger Remeirdes (EPFL – Lausanne). During my PhD I am based at TCV - a tokamak based at EPFL, Lausanne, Switzerland. A unique feature of TCV is that there is a lot of freedom to “shape” the plasma, which can potentially lead to lower heat loads. My job at TCV is to look at the light radiated by the plasma near the plasma facing components with a spectrometer. By doing so, we can deduce the plasma parameters at the divertor. With these parameters we can work on a better understanding of how shaping the plasma can affect the heat load.
Previously, I’ve done a double master program in Fusion and Applied Physics at Eindhoven University of Technology. The thing that attracts me about fusion is its extreme diversity. It is extremely international (I’ve had the opportunity to both do research at JET in the UK and F4E in Barcelona). It is also diverse in disciplines – physics, mathematics and computer science (modelling), engineering (both mechanical and electrical) – all coming together for one purpose: achieving fusion on earth, mainly for the production of energy.
As my graduation project (in cooperation with the Coherence Quantum Technology (CQT) group at applied physics), I’m studying the interaction of nano-clusters with ultrashort, intense laser pulses in order to accelerate ions to induce fusion reactions: generating a neutron pulse. By having a better understanding of this process theoretically it is possible to tailor the interaction in such a way that an ultrashort neutron pulse can be generated. Ultrashort neutron pulses are a novel concept and show great promise in material science and bioresearch.
Supervisors: Bruce Lipschultz (York), Holger Reimerdes (EPFL), Basil Duval (EPFL), Niek Lopes Cardozo (TU/e), and Seth Brussaard (TU/e)
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Cluster Fusion (MSc. Project TU/e) by Kevin Verhaegh
of nano-clusters pro duce s extremely high ion charges and high ion energies in a very short time. This can be used for various applications, such as highly intense x-ray sources, neutron sources and nucleosynthesis .
To tailor the ion energy distribution understanding the physics
underlying the laser-cluster interaction is of paramount importance. A first goal is to create as implified analytical model that describes and predicts the laser-cluster interaction. This is compared to experimental results from literature and fully relativistic particle tracer simulations. A second goal is to use this model to investigate whether the ion dynamics can be tailored such that nuclear fusion reactions are induced inside a nano-cluster, possibly leading to ultrashort neutron pulses.
the cluster are ionised, the cluster is stripped of its electrons and the resulting cluster explodes
due to an excess of repelling ions. We have investigated the possibility of inducing fusion reactions
during the explosion of a single deuterium cluster with density gradients. Due to these density
gradients, it is possible for the inside of the cluster to collide against the outside of the cluster
during explosion, which can result in ultra-short neutron pulses (less than 1 picosecond) with a
limited neutron yield of 1 neutron expected per 10 clusters. This indicates that single cluster
fusion might be viable as an ultrashort neutron pulse when many clusters can be irradiated in
one shot (in order to determine this, more analysis is required) and when a high intensity laser
pulse can be applied on the cluster.
density), high ion energies and high ion charges are obtained in a very short amount of time.
These high ion energies can be used to induce fusion reactions: cluster fusion. In current cluster
fusion experiments sub nanosecond neutron pulses of 104 − 1e6 neutrons per pulse with Q-values
of 1e8 − 1e7 are obtained. We have devised a simplified process-based laser-single cluster
interaction model for ascertaining the theoretical feasibility of single cluster fusion (fusion within
one exploding nano-cluster upon laser irradiation) and for ascertaining the possibility of generating
mono-energetic ion energy spectra from a single cluster for enhancing fusion yields in current
cluster fusion schemes.
Laser-cluster interaction has been dissected in three processes: inner field ionisation, electron
ejection and cluster expansion. In low-Z laser-cluster interaction, these processes occur sequen
tially. Field ionisation rapidly ionises the cluster, creating a nano-plasma. The resulting electron
cloud is subjective to a driving force by the laser field and a retaining force by the ion cloud, res
ulting in a forced oscillator model for the electron cloud motion during the laser pulse irradiation,
which is used for determining the portion of ejected electrons from the cluster. After electron
ejection, the cluster obtains an ion charge excess causing the cluster to expand under its self
generated potential, accelerating the cluster ions to high energies when all electrons are ejected.
In the case of high-Z laser-cluster interaction we have shown that the electron cloud oscillation and
field ionisation processes occur simultaneously and have a synergistic effect on each other, which
explains why extraordinarily high charge states can be obtained by laser-single cluster interaction.
We used our process-based model to show that it is theoretically possible to obtain nuclear
fusion for deuterium-deuterium, deuterium-tritium and proton-boron fuel mixes from a single ex
ploding nano-cluster by using peaked density cluster profiles and/or by combining ion species with
a different mass/charge ratio. Single cluster fusion results in a sub picosecond neutron (deuterium
deuterium, deuterium-tritium fusion) / α radiation (proton-boron fusion) pulse, which can poten
tially lead to very high instantaneous (pulsed) neutron fluxes of up to 1e22 − 1e24 neutrons/s m2.
Additionally, we have shown that it is theoretically possible to obtain mono-energetic ion energy
spectra from cluster fusion by controlling the density profile in a double pulse set-up, which can
enhance the fusion yield in current cluster fusion schemes by up to a factor 4.
density), high ion energies and high ion charges are obtained in a very short amount of time.
These high ion energies can be used to induce fusion reactions: cluster fusion. In current cluster
fusion experiments sub nanosecond neutron pulses of 1e4 − 1e6 neutrons per pulse with Q-values
of 1e−8 − 1e−7 are obtained. We have devised a simplified process-based laser-single cluster
interaction model for ascertaining the theoretical feasibility of single cluster fusion (fusion within
one exploding nano-cluster upon laser irradiation) and for ascertaining the possibility of generating
mono-energetic ion energy spectra from a single cluster for enhancing fusion yields in current
cluster fusion schemes.
Laser-cluster interaction has been dissected in three processes: inner field ionisation, electron
ejection and cluster expansion. In low-Z laser-cluster interaction, these processes occur sequen
tially. Field ionisation rapidly ionises the cluster, creating a nano-plasma. The resulting electron
cloud is subjective to a driving force by the laser field and a retaining force by the ion cloud, resulting in a forced oscillator model for the electron cloud motion during the laser pulse irradiation,
which is used for determining the portion of ejected electrons from the cluster. After electron
ejection, the cluster obtains an ion charge excess causing the cluster to expand under its self
generated potential, accelerating the cluster ions to high energies when all electrons are ejected.
In the case of high-Z laser-cluster interaction we have shown that the electron cloud oscillation and
field ionisation processes occur simultaneously and have a synergistic effect on each other, which
explains why extraordinarily high charge states can be obtained by laser-single cluster interaction.
We used our process-based model to show that it is theoretically possible to obtain nuclear
fusion for deuterium-deuterium, deuterium-tritium and proton-boron fuel mixes from a single ex
ploding nano-cluster by using peaked density cluster profiles and/or by combining ion species with
a different mass/charge ratio. Single cluster fusion results in a sub picosecond neutron (deuterium
deuterium, deuterium-tritium fusion) / α radiation (proton-boron fusion) pulse, which can poten
tially lead to very high instantaneous (pulsed) neutron fluxes of up to 1e22 − 1e24 neutrons/s m^2.
Additionally, we have shown that it is theoretically possible to obtain mono-energetic ion energy
spectra from cluster fusion by controlling the density profile in a double pulse set-up, which can
enhance the fusion yield in current cluster fusion schemes by up to a factor 4.
The interaction of intense femtosecond laser pulses with nano-clusters of solid state density to obtain fast ions is studied using particle tracer simulations. Because each cluster contains a limited amount of particles (104 -105) each particle can be traced. Compared to PIC simulations, this new approach should give more accurate and detailed results. The goal is to optimize experimental conditions for maximum neutron flux and minimum pulse duration.
Conference contributions by Kevin Verhaegh
Pre prints by Kevin Verhaegh
of nano-clusters pro duce s extremely high ion charges and high ion energies in a very short time. This can be used for various applications, such as highly intense x-ray sources, neutron sources and nucleosynthesis .
To tailor the ion energy distribution understanding the physics
underlying the laser-cluster interaction is of paramount importance. A first goal is to create as implified analytical model that describes and predicts the laser-cluster interaction. This is compared to experimental results from literature and fully relativistic particle tracer simulations. A second goal is to use this model to investigate whether the ion dynamics can be tailored such that nuclear fusion reactions are induced inside a nano-cluster, possibly leading to ultrashort neutron pulses.
the cluster are ionised, the cluster is stripped of its electrons and the resulting cluster explodes
due to an excess of repelling ions. We have investigated the possibility of inducing fusion reactions
during the explosion of a single deuterium cluster with density gradients. Due to these density
gradients, it is possible for the inside of the cluster to collide against the outside of the cluster
during explosion, which can result in ultra-short neutron pulses (less than 1 picosecond) with a
limited neutron yield of 1 neutron expected per 10 clusters. This indicates that single cluster
fusion might be viable as an ultrashort neutron pulse when many clusters can be irradiated in
one shot (in order to determine this, more analysis is required) and when a high intensity laser
pulse can be applied on the cluster.
density), high ion energies and high ion charges are obtained in a very short amount of time.
These high ion energies can be used to induce fusion reactions: cluster fusion. In current cluster
fusion experiments sub nanosecond neutron pulses of 104 − 1e6 neutrons per pulse with Q-values
of 1e8 − 1e7 are obtained. We have devised a simplified process-based laser-single cluster
interaction model for ascertaining the theoretical feasibility of single cluster fusion (fusion within
one exploding nano-cluster upon laser irradiation) and for ascertaining the possibility of generating
mono-energetic ion energy spectra from a single cluster for enhancing fusion yields in current
cluster fusion schemes.
Laser-cluster interaction has been dissected in three processes: inner field ionisation, electron
ejection and cluster expansion. In low-Z laser-cluster interaction, these processes occur sequen
tially. Field ionisation rapidly ionises the cluster, creating a nano-plasma. The resulting electron
cloud is subjective to a driving force by the laser field and a retaining force by the ion cloud, res
ulting in a forced oscillator model for the electron cloud motion during the laser pulse irradiation,
which is used for determining the portion of ejected electrons from the cluster. After electron
ejection, the cluster obtains an ion charge excess causing the cluster to expand under its self
generated potential, accelerating the cluster ions to high energies when all electrons are ejected.
In the case of high-Z laser-cluster interaction we have shown that the electron cloud oscillation and
field ionisation processes occur simultaneously and have a synergistic effect on each other, which
explains why extraordinarily high charge states can be obtained by laser-single cluster interaction.
We used our process-based model to show that it is theoretically possible to obtain nuclear
fusion for deuterium-deuterium, deuterium-tritium and proton-boron fuel mixes from a single ex
ploding nano-cluster by using peaked density cluster profiles and/or by combining ion species with
a different mass/charge ratio. Single cluster fusion results in a sub picosecond neutron (deuterium
deuterium, deuterium-tritium fusion) / α radiation (proton-boron fusion) pulse, which can poten
tially lead to very high instantaneous (pulsed) neutron fluxes of up to 1e22 − 1e24 neutrons/s m2.
Additionally, we have shown that it is theoretically possible to obtain mono-energetic ion energy
spectra from cluster fusion by controlling the density profile in a double pulse set-up, which can
enhance the fusion yield in current cluster fusion schemes by up to a factor 4.
density), high ion energies and high ion charges are obtained in a very short amount of time.
These high ion energies can be used to induce fusion reactions: cluster fusion. In current cluster
fusion experiments sub nanosecond neutron pulses of 1e4 − 1e6 neutrons per pulse with Q-values
of 1e−8 − 1e−7 are obtained. We have devised a simplified process-based laser-single cluster
interaction model for ascertaining the theoretical feasibility of single cluster fusion (fusion within
one exploding nano-cluster upon laser irradiation) and for ascertaining the possibility of generating
mono-energetic ion energy spectra from a single cluster for enhancing fusion yields in current
cluster fusion schemes.
Laser-cluster interaction has been dissected in three processes: inner field ionisation, electron
ejection and cluster expansion. In low-Z laser-cluster interaction, these processes occur sequen
tially. Field ionisation rapidly ionises the cluster, creating a nano-plasma. The resulting electron
cloud is subjective to a driving force by the laser field and a retaining force by the ion cloud, resulting in a forced oscillator model for the electron cloud motion during the laser pulse irradiation,
which is used for determining the portion of ejected electrons from the cluster. After electron
ejection, the cluster obtains an ion charge excess causing the cluster to expand under its self
generated potential, accelerating the cluster ions to high energies when all electrons are ejected.
In the case of high-Z laser-cluster interaction we have shown that the electron cloud oscillation and
field ionisation processes occur simultaneously and have a synergistic effect on each other, which
explains why extraordinarily high charge states can be obtained by laser-single cluster interaction.
We used our process-based model to show that it is theoretically possible to obtain nuclear
fusion for deuterium-deuterium, deuterium-tritium and proton-boron fuel mixes from a single ex
ploding nano-cluster by using peaked density cluster profiles and/or by combining ion species with
a different mass/charge ratio. Single cluster fusion results in a sub picosecond neutron (deuterium
deuterium, deuterium-tritium fusion) / α radiation (proton-boron fusion) pulse, which can poten
tially lead to very high instantaneous (pulsed) neutron fluxes of up to 1e22 − 1e24 neutrons/s m^2.
Additionally, we have shown that it is theoretically possible to obtain mono-energetic ion energy
spectra from cluster fusion by controlling the density profile in a double pulse set-up, which can
enhance the fusion yield in current cluster fusion schemes by up to a factor 4.
The interaction of intense femtosecond laser pulses with nano-clusters of solid state density to obtain fast ions is studied using particle tracer simulations. Because each cluster contains a limited amount of particles (104 -105) each particle can be traced. Compared to PIC simulations, this new approach should give more accurate and detailed results. The goal is to optimize experimental conditions for maximum neutron flux and minimum pulse duration.