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Simulated transverse electron beam distribution at the exit from the gun (left) and corresponding horizontal beam profile (right).
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The FAIR heavy-ion synchrotrons SIS18 and SIS100 as part of the new FAIR accelerator facility at GSI will be operated at the “space charge limit” for light and heavy-ion beams. In SIS100 beam loss due to space charge induced resonance crossing should not exceed a few percent during the 1 s injection plateau. In order to further increase the beam in...
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... grid will soon be replaced by a more refined grid, allowing for better control of the shape of the transverse electron beam profile. Figure 6 displays the result of a simulation for an extracted electron beam with a round transverse distribution at the exit of the gun using the refined grid. ...
Citations
... The second reason is the longitudinal bunch shape, along which the line density λ varies, 0 ≤ λðzÞ ≤ λ max . A Gaussian shaped bunch of rms bunch length σ z features a maximum line density of λ max ¼ N=ð ffiffiffiffiffi ffi 2π p σ z Þ. Pulsed electron lenses aim to reduce the space charge tune spread by suppressing the longitudinal variation of λðzÞ [16,[25][26][27]: A copropagating electron beam pulse is shaped to longitudinally match the circulating hadron bunch. In the particular case of pulsed linear electron lenses, as employed in our Letter, the electron beam is distributed homogeneously in the transverse plane. ...
To produce ultimate high-brightness hadron beams, synchrotrons need to overcome a most prominent intensity limitation, i.e., space charge. This Letter characterizes the potential of pulsed electron lenses in detailed 3D tracking simulations, key to which is a realistic machine and space charge model. The space charge limit, imparted by betatron resonances, is shown to be increased by up to 50% using a low symmetric number of electron lenses in application to the Facility for Antiproton and Ion Research SIS100 synchrotron. Conceptually, a 100% increase is demonstrated with a larger number of electron lenses, which is found to rapidly saturate near the theoretical 2D limit.
... A PEL was initially proposed for space-charge compensation [9] and investigated further in [10] for application in SIS100 heavy-ion synchrotron [11]. A prototype PEL is being developed [12,13] to be installed in SIS18 * vadim.gubaidulin@synchrotron-soleil.fr Figure 1: Schematic layout of a pulses electron lens. A transverse cross-section of ion and electron beams is shown above it in black and red, respectively. ...
A pulsed electron lens produces a betatron tune shift along a hadron bunch as a function of the longitudinal coordinates, which is a longitudinal detuning. An example of transverse detuning is the tune shifts due to octupole magnets. This paper considers a pulsed electron lens as a measure to mitigate the head-tail instabilities. The analytical predictions are compared with the results of the particle tracking simulations. A pulsed electron lens is demonstrated to be a source of tune spread with two components: a static one, leading to Landau damping; and a dynamic one, leading to an effective impedance modification, which we demonstrate analytically and in our particle tracking simulations. The effective impedance modification can be important for beam stability due to devices causing longitudinal detuning, especially for nonzero head-tail modes. We explore two types of pulsed electron lenses: one with a homogeneous transverse distribution and another with a Gaussian distribution.
... The prototype electron lens for space charge compensation is being designed for the integration into the SIS18 and potentially the SIS100 synchrotron at GSI/FAIR. However, the SIS18 will serve as testbed to demonstrate the space charge compensation scheme and the electron lens with an interaction length of 3.36 m will be installed in one of the available drift sections [1]. The SIS18 ion beam has an elliptical cross section over the length of the interaction region and has to be transversally embedded into a homogeneous electron beam while the pulse needs to be exactly matched to the bunch form in order to avoid over-compensation of the bunch head and tail as presented in [2]. ...
At GSI a prototype electron lens for space charge (SC) compensation is currently being designed and main components as the RF-modulated electron gun are already under commissioning. The goal of this project is the (partial) compensation of SC forces within the ion beam by an overlapping electron beam. This may help to increase the intensity of primary beams, especially in the FAIR facility and potentially all large synchrotrons operated at the SC limit. For an effective SC compensation, the generated electron beam needs to follow the transverse and longitudinal beam profile of the ion bunch structure. The requirements are maximum currents of 10 A and grid modulation to cover a broad frequency range from 400 kHz to 1 MHz. The RF-modulated electron gun was designed and manufactured in the scope of the ARIES collaboration and is currently being tested at the E-Lens Lab of Goethe-University Frankfurt. A dedicated test bench was built for commissioning of the major e-lens components and diagnostics. In this contribution the overall set-up will be presented putting special emphasis on the beam dynamics and collector design as well as simulation results of the electron gun.
... The prototype electron lens for space charge compensation is being designed for the integration into the SIS18 and potentially the SIS100 synchrotron at GSI/FAIR. However, the SIS18 will serve as testbed to demonstrate the space charge compensation scheme and the electron lens with an interaction length of 3.36 m will be installed in one of the available drift sections [1]. The SIS18 ion beam has an elliptical cross section over the length of the interaction region and has to be transversally embedded into a homogeneous electron beam while the pulse needs to be exactly matched to the bunch form in order to avoid over-compensation of the bunch head and tail as presented in [2]. ...
... Instead, a dc EL relies on the transverse nonlinearity of the electron beam's electromagnetic field providing tune shifts depending on the transverse single-particle amplitudes. In the SIS18, a prototype PEL will be installed [20]. The resulting increase in the spacecharge limit and an optimal number of electron lenses in the SIS18/SIS100 are under investigation in [20,21]. ...
... In the SIS18, a prototype PEL will be installed [20]. The resulting increase in the spacecharge limit and an optimal number of electron lenses in the SIS18/SIS100 are under investigation in [20,21]. The effect of a PEL on coherent beam dynamics and on transverse beam stability is the topic of this contribution. ...
... (6.185) and (6.187) in [30] ] for arbitrary longitudinal detuning. It has been modified w.r.t Eq. (20) in [13] and Eq. (9) in [33] (where it is denoted as Λ) to include Q s ðJ z ; φÞ in the integral to account for ΔQ s ðJ z ; φÞ detuning and its effect on the betatron phase factor. ...
A pulsed electron lens produces a betatron tune shift along a hadron bunch as a function of the longitudinal coordinates, which is a longitudinal detuning. An example of transverse detuning is the tune shifts due to octupole magnets. This paper considers a pulsed electron lens as a measure to mitigate the head-tail instabilities. Using a detailed analytical description within a Vlasov formalism, the coherent properties of the longitudinal and transverse detuning are presented. The analytical predictions are compared with the results of the particle tracking simulations. A pulsed electron lens is demonstrated to be a source of tune spread with two components: a static one, leading to Landau damping and a dynamic one, leading to an effective impedance modification, which we demonstrate analytically and in our particle tracking simulations. The effective impedance modification can be important for beam stability due to devices causing longitudinal detuning, especially for nonzero head-tail modes. The Vlasov formalism is extended to include the combination of longitudinal and transverse detuning. As a possible application at the SIS100 heavy-ion synchrotron [Facility for Antiproton and Ion Research (FAIR) at GSI Darmstadt, Germany], a combination of a pulsed electron lens with octupole magnets is considered.
... Instead a DC EL relies on the transverse nonlinearity of the electron beam's electromagnetic field providing tune shifts depending on the transverse single-particle amplitudes. In the SIS18, a prototype PEL will be installed [19] and the resulting increase of the space charge limit in the SIS18/SIS100 is under investigation [19,20]. The effect of a PEL on coherent beam dynamics and on transverse beam stability are the topic of the this contribution. ...
... Instead a DC EL relies on the transverse nonlinearity of the electron beam's electromagnetic field providing tune shifts depending on the transverse single-particle amplitudes. In the SIS18, a prototype PEL will be installed [19] and the resulting increase of the space charge limit in the SIS18/SIS100 is under investigation [19,20]. The effect of a PEL on coherent beam dynamics and on transverse beam stability are the topic of the this contribution. ...
... This extends the Sacherer's integral equation [29]. Using the Laclare's approach [30], an expression for λ l (p 0 ) is obtained by multiplying both sides of Eq. (19) by H l p 0 [I l (Q coh )dJ x dJ y ] rdr and integrating: ...
A pulsed electron lens produces a betatron tune shift along a hadron bunch as a function of the longitudinal coordinates, which is a longitudinal detuning. An example of transverse detuning are the tune shifts due to octupole magnets. This paper considers a pulsed electron lens as a measure to mitigate the head-tail instabilities. Using a detailed analytical description within a Vlasov formalism, the coherent properties of the longitudinal and transverse detuning are presented. The analytical predictions are compared with the results of the particle tracking simulations. A pulsed electron lens is demonstrated to be a source of tune spread with two components: a static one, leading to Landau damping; and a dynamic one, leading to an effective impedance modification, which we demonstrate analytically and in our particle tracking simulations. The effective impedance modification can be important for beam stability due to devices causing a longitudinal detuning, especially for nonzero head-tail modes. The Vlasov formalism is extended to include the combination of longitudinal and transverse detuning. As a possible application at the SIS100 heavy-ion synchrotron (FAIR at GSI Darmstadt, Germany), a combination of a pulsed electron lens with octupole magnets is considered.
... A recently published study in Ref. [37] demonstrates the effect of three of such pulsed electron lenses, which are placed symmetrically around the circumference, in FFSC simulations for SIS100. The intensity of the electron pulse is adjusted such that the linear part of the space charge force is compensated by half, thus strongly reducing the space charge tune spread. ...
The SIS100 synchrotron as a part of the new Facility for Antiproton and Ion Research (FAIR) accelerator facility at GSI should be operated at the "space charge limit" for light-and heavy-ion beams. Beam losses due to space-charge-induced resonance crossing should not exceed a few percent during a full cycle. The recent advances in the performance of particle tracking tools with self-consistent solvers for the 3D space charge forces now allow us to reliably identify low-loss areas in tune space, considering the full SIS100 accumulation plateau of one second (160 000 turns) duration. A realistic magnet error model, extracted from precise bench measurements of the SIS100 main dipole and quadrupole magnets, is included in the simulations. Previously, such beam dynamics simulations required non-self-consistent space charge models. By comparing to the self-consistent simulations results, we are now able to demonstrate that the predictions from such faster space charge models can be used to identify low-loss regions with sufficient accuracy. The findings are applied by identifying a low-loss working point region in SIS100 for the design FAIR beam parameters. The bunch intensity at the space charge limit is determined. Several countermeasures to space charge are proposed to enlarge the low-loss area and to further increase the space charge limit.
... A recently published study in Ref. [32] demonstrates the effect of three of such pulsed electron lenses, which are placed symmetrically around the circumference, in FFSC simulations for SIS100. The intensity of the electron pulse is adjusted such that the linear part of the space charge force is compensated by half, thus strongly reducing the space charge tune spread. ...
The SIS100 synchrotron as a part of the new FAIR accelerator facility at GSI should be operated at the "space charge limit" for light and heavy ion beams. Beam losses due to space charge induced resonance crossing should not exceed a few percent during a full cycle. The recent advances in the performance of particle tracking tools with self-consistent solvers for the 3D space charge forces now allow us to reliably identify low-loss areas in tune space, considering the full 1s ($\mathcal{O}(10^5)$ turns) accumulation plateau in SIS100. A realistic magnet error model, extracted from precise bench measurements of the SIS100 main dipole and quadrupole magnets, is included in the simulations. Previously such beam dynamics simulations required non-self-consistent space charge models. By comparing to the self-consistent simulations results we are now able to demonstrate that the predictions from such faster space charge models can be used to identify low-loss regions with sufficient accuracy. The findings are applied by identifying a low-loss working point region in SIS100 for the design FAIR beam parameters. The bunch intensity at the space charge limit is determined. Several counter-measures to space charge are proposed to enlarge the low-loss area and to further increase the space charge limit.
... Recently, hollow electron lenses for active halo control were included among the upgrades of the Large Hadron Collider at CERN to reach higher luminosities (HL-LHC Project) [24][25][26][27][28][29][30]. Future applications also include space-charge compensation in synchrotrons at FAIR [31]. The electron lens is based on low-energy, magnetically confined electron beams overlapping with the circulating beam in a straight section of a circular particle accelerator or storage ring. ...
... The full definition of pulse timing requirements for the SCC e-lens is underway. We note that a similar research program, targeted to the synchrotrons for FAIR, is being carried out at GSI [31,58,84]. ...
The electron lens in the Fermilab Integrable Optics Test Accelerator (IOTA) will enable new research in nonlinear integrable optics, space-charge compensation, electron cooling, and the stability of intense beams. This research addresses scientific questions on high-brightness beams and operational challenges of high-power accelerators for nuclear and particle physics. We review the roles that electron lenses play in this field and the physical principles behind their applications. The design criteria and specifications for the IOTA storage ring and electron lens are then discussed. We conclude with a description of the components of the apparatus.
