Diagnostics of highly charged plasmas with multicomponent 1+ ion injection

Abstract

We establish multicomponent 1+ injection into a charge breeder electron cyclotron resonance ion source and an associated computational procedure as a noninvasive probe of the electron density n e , average electron energy E e , and the characteristic times of ionization, charge exchange, and ion confinement of stochastically heated, highly charged plasma. Multicomponent injection allows refining the n e , E e ranges, reducing experimental uncertainty. Na/K injection is presented as a demonstration. The E e and n e of a hydrogen discharge are found to be 600 +600 −300 eV and 8 +8 −3 × 10 11 cm −3 , respectively. The ionization, charge exchange, and confinement times of high charge state alkali ions are on the order of 1 ms-10 ms.

Application of Optical Emission Spectroscopy to Electron Cyclotron Resonance Ion Sources

“…In an ECRIS plasma, the temporal evolution of the ion density of a given charge state n q i (q being the charge state) is described by a set of coupled non-linear differential equations, called balance equations, that take into account three dominant processes: i) step-by-step ionization by electron impact, ii) charge exchange and iii) diffusion or transport. If plasma is assumed to be in dynamic equilibrium, balance equations can be written as follows [14,15,16]:…”

Method for estimating charge breeder ECR ion source plasma parameters with short pulse 1+ injection of metal ions

“…Typical uncertainties of high charge state potassium confinement and charge exchange times are 100-200% while the ionization times can be estimated more accurately, i.e. with 40-70% relative uncertainty [18][19][20][21], which raises the concern that the CT method might not be able to detect small variations of the plasma parameters. Thus, the statistical relevance of the measurement results presented above could be questioned.…”

“…It has been shown that the inherent uncertainties of the CT method can be reduced e.g. by two-component injection or overlapping the (⟨E e ⟩ , n e ) solution sets of neighbouring charge states albeit with the caveat of additional assumption [20]. Furthermore, it has been demonstrated that the main contributor to the large relative uncertainty of the CT method is the lack of precise ionization cross section data whereas the presumed EED has a smaller effect [21].…”

“…In this paper we apply the CT method for parametric studies of the CB-ECRIS plasma. We do not detail the method itself but rather refer the reader to the literature [18][19][20][21] for a comprehensive account of the assumptions, computational details and data analysis.…”