Eylem Seç
A combined phase contrast imaging and heterodyne interferometer system for multiscale fluctuation measurements on DIII-D
Başlık:
A combined phase contrast imaging and heterodyne interferometer system for multiscale fluctuation measurements on DIII-D
Yazar:
Davis, Evan Michael, author.
Yazar Ek Girişi:
Genel Not:
Source: Dissertation Abstracts International, Volume: 79-10(E), Section: B.
Advisors: Miklos Porkolab.
Özet:
A novel combined diagnostic capable of measuring multiscale density fluctuations that extend from magnetohydrodynamic (MHD) scales to the lower bound of the electron temperature gradient (ETG) mode has been designed, installed, and operated at the DIII-D tokamak. The combined diagnostic was constructed by adding a heterodyne interferometer to the pre-existing phase contrast imaging (PCI) system, both of which measure line-integrated electron-density fluctuations. The port-space footprint is minimized by using a single 10.6 mum CO 2 laser and a single beampath. With temporal bandwidths in excess of 1 MHz, the PCI measures high-k (1.5 cm-1 ⩽ 25 cm-1) fluctuations with sensitivity 3 x 10 13 m-2/ kHz , while the interferometer simultaneously measures low-k (
The combined PCI-interferometer was operated during an experiment in which the ETG drive alpha/LTe and the ion temperature gradient (ITG) drive alpha/LTA were locally modified in an attempt to elicit a multiscale turbulent response. Numerous turbulent branches are observed. In particular, the interferometer measures a low-k electromagnetic mode driven unstable by collisionality, properties consistent with the micro-tearing mode (MTM), and the PCI measures a turbulent mode that exhibits distinct "spectral flattening" when increasing alpha/LTe relative to alpha/LTi , hypothesized to be a tell-tale signature of increased cross-scale coupling. Linear-stability analysis and quasilineartransport modeling are performed with the trapped gyro-Landau fluid code TGLF, and qualitative agreement with the PCI-measured spectral flattening is obtained. Further, via toroidal correlation with DIII-D's primary interferometer, the measurement of core-localized MHD toroidal mode numbers has been demonstrated. Where comparisons can be made with magnetic probes, the interferometer-measured toroidal mode numbers are typically in good agreement. Unfortunately, the 4 cm major-radial offset between the interferometer beam centers in DIII-D can bias the mode-number measurement, limiting widespread use of this capability until a robust compensation technique is developed. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs mit.edu).
Notlar:
School code: 0753
Tüzel Kişi Ek Girişi:
Mevcut:*
Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(687345.1) | 687345-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
On Order
Liste seç
Bunu varsayılan liste yap.
Öğeler başarıyla eklendi
Öğeler eklenirken hata oldu. Lütfen tekrar deneyiniz.
:
Select An Item
Data usage warning: You will receive one text message for each title you selected.
Standard text messaging rates apply.