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The new Stockholm Electron Beam Ion Trap (S-EBIT)
Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
Visa övriga samt affilieringar
2010 (Engelska)Ingår i: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 5, s. C12018-Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

A new laboratory for highly charged ions is being built up at Stockholm University. A fully refrigerated electron beam ion trap (R-EBIT, 3 T magnet, 30 keV electron energy) was installed. It was used for spectroscopic studies, ion cooling experiments, electron ion collisions, and highly-charged ion surface studies. Here we report on an upgrade of this EBIT to a ``Super EBIT'' (S-EBIT, 4 T magnet, 260 keV electron energy). The high-voltage trapping system, the ion injection as well as the extraction scheme of S-EBIT and the LabView based operational system of S-EBIT are described.

Ort, förlag, år, upplaga, sidor
2010. Vol. 5, s. C12018-
Nationell ämneskategori
Atom- och molekylfysik och optik
Forskningsämne
fysik
Identifikatorer
URN: urn:nbn:se:su:diva-57786DOI: 10.1088/1748-0221/5/12/C12018OAI: oai:DiVA.org:su-57786DiVA, id: diva2:417990
Konferens
International Symposium on Electron Beam Ion Sources and Traps (EBIST), Stockholm University, April 7th - 10th, 2010
Tillgänglig från: 2011-05-19 Skapad: 2011-05-19 Senast uppdaterad: 2017-12-11Bibliografiskt granskad
Ingår i avhandling
1. The Penning trap mass spectrometer SMILETRAP II and evaporative cooling of highly-charged ions
Öppna denna publikation i ny flik eller fönster >>The Penning trap mass spectrometer SMILETRAP II and evaporative cooling of highly-charged ions
2011 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Accurate mass values have wide-ranging applications in physics and metrology, allowing, for example, to test quantum electrodynamics and fundamental symmetries, to determine fundamental constants, and to establish weight standards.

This thesis describes the new high-precision double-Penning trap mass spectrometer SMILETRAP II which aims at relative uncertainties in the mass determination of 10-10 and below. SMILETRAP II exploits the merits of highly-charged ions as the relative precision in the mass determination with Penning traps is directly proportional to the charge state of the ion. The spectrometer was therefore connected to the electron beam ion trap S-EBIT which is designed to produce bare ions of practically any element up to uranium.

Technical and experimental developments were realized to overcome limitations that restricted the achievable precision at the former spectrometer SMILETRAP I. The technical developments include, for example, an ion detection setup with close to 100% efficiency and an extremely stable temperature-regulation system. Temperature fluctuations constitute a main limitation for the attainable precision.

Cold ions are a prerequisite to reach high precision in experiments with Penning traps. This makes cooling of the ions from the ion sources necessary. Ion temperature measurement and cooling experiments were performed. The transverse temperature of the trapped ions was determined via the emittance of extracted ions. A pepperpot emittance meter was designed to meet the requirements of low-energy, low-intensity beams. To measure the axial temperature and assess the ions’ longitudinal phase-space density, a coherent extraction method was developed. The evaporative cooling technique was successfully implemented. In particular, evaporative cooling of highly-charged ions in a Penning trap could be observed for the first time.

Ort, förlag, år, upplaga, sidor
Stockholm: Department of Physics, Stockholm University, 2011. s. 82
Nyckelord
Penning trap, Precision mass spectrometry, Atomic mass, Highly-charged ions, Evaporative cooling, Coherent oscillation, Ion beam emittance
Nationell ämneskategori
Atom- och molekylfysik och optik
Forskningsämne
fysik
Identifikatorer
urn:nbn:se:su:diva-57787 (URN)978-91-7447-317-9 (ISBN)
Disputation
2011-06-17, FA32, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (Engelska)
Opponent
Handledare
Anmärkning
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Epub ahead of print. Paper 6: Accepted. Tillgänglig från: 2011-05-26 Skapad: 2011-05-19 Senast uppdaterad: 2011-05-20Bibliografiskt granskad
2. Electron - Ion Recombination Data for Plasma Applications: Results from Electron Beam Ion Trap and Ion Storage Ring
Öppna denna publikation i ny flik eller fönster >>Electron - Ion Recombination Data for Plasma Applications: Results from Electron Beam Ion Trap and Ion Storage Ring
2012 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This thesis contains results of electron-ion recombination processes in atomic ions relevant for plasma applications. The measurements were performed at the Stockholm Refrigerated Electron Beam Ion Trap (R-EBIT) and at the CRYRING heavy-ion storage ring. Dielectronic recombination (DR) cross sections, resonant strengths, rate coefficients and energy peak positions in H-like and He-like S are obtained for the first time from the EBIT measurements. Furthermore, the experimentally obtained DR resonant strengths are used to check the behaviour of a scaling formula for low Z, H-and He-like iso-electronic sequences and to update the fitting parameters. KLL DR peak positions for initially He- to B-like Ar ions are obtained experimentally from the EBIT measurements. Both the results from highly charged sulfur and argon are compared with the calculations performed with a distorted wave approximation.

Absolute recombination rate coefficients of B-like C, B-like Ne and Be-like F ions are obtained for the first time with high energy resolution from storage ring measurements. The experimental results are compared with the intermediate coupling AUTOSTRUCTURE calculations. Plasma rate coefficients of each of these ions are obtained by convoluting the energy dependent recombination spectra with a Maxwell-Boltzmann energy distribution in the temperature range of 103-106 K. The resulting plasma rate coefficients are presented and compared with the calculated data available in literature.

Ort, förlag, år, upplaga, sidor
Stockholm: Department of Physics, Stockholm University, 2012. s. 64
Nyckelord
Highly charged ions, Atomic processes, Atomic data, Electron-ion recombination, Plasmas
Nationell ämneskategori
Fysik Atom- och molekylfysik och optik
Forskningsämne
fysik
Identifikatorer
urn:nbn:se:su:diva-75311 (URN)978-91-7447-497-8 (ISBN)
Disputation
2012-05-14, sal FA31, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 10:00 (Engelska)
Opponent
Handledare
Anmärkning

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Accepted. Paper 5: Accepted. Paper 6: Manuscript. Paper 7: Manuscript.

Tillgänglig från: 2012-04-22 Skapad: 2012-04-14 Senast uppdaterad: 2013-08-20Bibliografiskt granskad
3. Transmission of slow highly charged ions through nano-structures
Öppna denna publikation i ny flik eller fönster >>Transmission of slow highly charged ions through nano-structures
2012 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This thesis is based on experimental investigations of transmitting slow highly charged ions through nano-structures of various cross-sections. Transmission through rhombic and rectangular nanocapillaries in muscovite and phlogopite mica, respectively, is used to study the guiding and shaping of highly charged ion beams. The two-dimensional angular distributions of the transmitted ions reveal that slow highly charged ion beams are tailored into rectangular and rhombic shapes after passing through the capillaries of rhombic and rectangular cross-sections, respectively. These transmission profiles are maintained for tilt angles within the geometrical opening angle of the capillaries. The ‘incident charge-dependent’ time evolution of the transmission profiles indicates that the tailored shape comes from the image force experienced by the traversing ions and the deposited charge by the incident ions moves the transmission profiles towards higher observation angles with respect to the beam direction. Transmission is also observed for tilt angles larger than the geometrical opening of the capillaries and evidence of charging-up of capillary walls was seen. Other incident charge-dependent features including the increase in angular width and shift of transmitted angular distributions were also observed. Starting from initially charged capillaries, it was found that the deposited charge must be distributed uniformly along the capillary walls to maintain the tailored rhombic shape through rectangular capillaries.

In this thesis, a technique is presented which is successfully employed to investigate directly the formation of charge patches on the walls of a glass capillary by imaging the visible photons emitted due to impact of ions on the walls. These tapered glass capillaries were applied in biological studies of cell damage by ion impact and the technique provides a new way to directly observe the development of ion-guiding in these capillaries. With the help of this technique the mechanism of ion-guiding can be controlled and optimized.

We also review the transmission characteristics of slow highly charged ions through nanometer thick foils and present the results of transmission of slow highly charged ions through ultra-thin carbon nano-sheets of molecular layer thickness. The observed energy loss is smaller than the calculated one using SRIM and agrees rather well with the Firsov model. The transmitted ions also keep their initial charge state up to 98% in a complete contradiction to the electron capture rate predicted by the classical over-the-barrier model. The results suggest that the energy loss of slow highly charged ions in such thin sheets is due to the electronic excitations, without charge exchange inside the target.

Ort, förlag, år, upplaga, sidor
Stockholm: Department of Physics, Stockholm University, 2012. s. 73
Nyckelord
Highly charged ions, nano-structures, nanocapillaries, ion-guiding
Nationell ämneskategori
Fysik
Forskningsämne
fysik
Identifikatorer
urn:nbn:se:su:diva-75470 (URN)978-91-7447-514-2 (ISBN)
Disputation
2012-05-24, FA31, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (Engelska)
Opponent
Handledare
Anmärkning

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 2: Submitted. Paper 3: Submitted. Paper 4: Accepted. Paper 5: Submitted.

Tillgänglig från: 2012-05-02 Skapad: 2012-04-19 Senast uppdaterad: 2012-04-23Bibliografiskt granskad
4. Interaction of atomic ions with electrons: Recombination rate coefficients for C1+, F5+, Ne5+, S14+,S15+
Öppna denna publikation i ny flik eller fönster >>Interaction of atomic ions with electrons: Recombination rate coefficients for C1+, F5+, Ne5+, S14+,S15+
2012 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This thesis concentrates on electron-ion interaction studies, in particular focusing on dielectronic recombination (DR) of highly charged ions relevant to astrophysics and plasma physics. The measurements were performed at the Stockholm Refrigerated Electron Beam Ion Trap (R-EBIT) and at the CRYRING heavy-ion storage ring. For the R-EBIT measurements a newly developed time-of-flight (TOF) technique for separation of ions and detecting the charge state distribution was utilized. By using ion intensities derived from the TOF spectra as input parameters in the rate equations, energy dependent DR rate coefficients for S15+ and S14+ ions were obtained for the first time. Resonance energies and cross sections calculated within the relativistic many-body perturbation theory for S15+ agree well with the experimental data. In addition to the TOF spectra, the x-ray spectra have been also collected. The combination of these two measurements allows us to separate the photo-recombination and the excitation spectra, from which the excitation rate coefficients for S15+ and S14+ ions were extracted.

From the storage ring measurements absolute recombination rate coefficients for C1+, F5+, and Ne5+ions as a function of electron-ion collision energy were obtained. These were reported for the first time with high energy resolution. The experimental results were compared with results obtained from AUTOSTRUCTURE calculations. Temperature dependent rate coefficients have been also derived for the studied ions and compared with calculations available in the literature.

Ort, förlag, år, upplaga, sidor
Stockholm: Department of Physics, Stockholm University, 2012. s. 71
Nationell ämneskategori
Atom- och molekylfysik och optik
Forskningsämne
fysik
Identifikatorer
urn:nbn:se:su:diva-75912 (URN)978-91-7447-529-6 (ISBN)
Disputation
2012-06-11, FB41, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 14:00 (Engelska)
Opponent
Handledare
Anmärkning

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Accepted. Paper 5: Manuscript. Paper 6: Accepted. Paper 7: Manuscript.

Tillgänglig från: 2012-05-10 Skapad: 2012-05-03 Senast uppdaterad: 2013-08-20Bibliografiskt granskad

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