EBIT sources

We locate the EBIT source and calibration source inside the Rowland circle by design. Bragg diffraction angles of calibration lines are in the range 29-45° while the helium-like resonances are observed around 39°. The plane of crystal dispersion is parallel to the electron beam axis. The crystal acts as a polarizer at Bragg angles near 45° and radiation polarised perpendicular to the electron beam axis is the dominant diffracted component. 

Fig. 1. Spectrometer configuration at NIST EBIT note that the EBIT source is located well inside the Rowland circle. The spectrometer is in the perpendicular orientation where the axis of the spectrometer is perpendicular to the long axis of the EBIT source. The detector arm moves vertically with changes in diffraction angle.

One example of a systematic shift is that caused by the calibration source not being in the same location as the EBIT source. Our theoretical modelling determines the shifts of < 1 arcsecond associated with this mis-location. The dispersion function is not a simple relationship between angle and wavelength but a complex (but smooth) function of reference wavelengths, clinometer values, detector scale and systematic shifts. 

Abstract. Absolute measurements of the energies of helium-like vanadium resonances on an electron beam ion trap (EBIT) axe reported. The results agree with recent theoretical calculations and the experimental precision (27-MO ppm) lies at the same level as the current uncertainty in theory (0.1 eV). The measurements represent a 5.7%-8% determination of the quantum electrodynamics (QED) contribution to the transition energies and are the most precise measurements of the helium-hke resonances in the Z = 19—31 range. These are the first precision X-ray measurements on the National Institute of Standards and Technology EBIT and strongly commend the EBIT as a new spectroscopic source for QED investigations. 

Most precision spectroscopy of medium Z ions has been conducted at accelerators or tokamak plasmas, but the recent development of the electron beam ion trap (EBIT) has offered a new spectroscopic source to experimenters. Our experimental method takes advantage of the Doppler free and relatively clean spectra produced by an EBIT and is coupled with an external calibration source to allow absolute measurement of highly charged ions. These are the first precision X-ray measurements conducted at the NIST EBIT [12],... 

Doppler shifts due to the low thermal velocities of the highly-charged ions in the EBIT are not significant sources of uncertainty. On average the Doppler shifts will be zero as there is no preferred direction of motion. Doppler broadening is 1.8 eV for IkeV ions and we allow for a possible 1% asymmetry of velocity distribution resulting in a maximum Doppler shift of < 0.02 eV or < 4 ppm. 

Summing all errors in quadrature results is a 27 ppm-40 ppm uncertainty. The main sources of uncertainty are therefore statistical, reference wavelengths and dispersion function determination. All major error sources are soft and may be reduced further. Methods of reducing statistical uncertainty by improving spectrometer efficiency are being investigated and improved flux from the EBIT has been achieved in other studies [26],... 

Electron Beam Ion Source (EBIS) and Ion Trap (EBIT). 2333... 

Some ion sources and fusion facilities in the plasma plane. PIG Penning Ion Gauge, ECRIS Electron Cyclotron Resonance Ion Source, EBIS/EBIT Electron Beam Ion Source or Trap, laser plasma produced by laser ablation in solids, tokamak fusion device of light ions, fully stripped uranium ion... 

By working principle, they can be classified as hot filament sources, ion sources based on Penning discharge (PIG), radio frequency (RF) and microwave (MW) ion sources, electron cyclotron resonance (ECR) ion sources, electron beam ion sources (EBIS, EBIT), laser ion sources, cusp and multicusp ion sources, sputtering ion sources. 

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