if temperature increases then number density Also increase??? in plasma
Answers
Answer:Plasma pressure profile measurement
Plasma pressure consists of many parameters; they are plasma density (ne,i), plasma temperature (Te,i), impurity (Zeff), and fast beam ions. Among these parameters, ion density (ni) and fast beam ions can not be measured directly in practice. In principle, the ion distribution including impurity ions can be measured using thermal scattering method which has not been hardened yet. Therefore, the ion density has to be estimated based on electron density (ne) and absolute impurity measurement (Zeff). Fast ion counts must be estimated from the calculation. Considering that the bulk ion temperature was recently addressed experimentally through impurity ion information, we have had a very little knowledge on the plasma pressures.
The most common diagnostic to measure electron information is Thomson scattering since it was tested on the T-3 tokamak using a single pulse Ruby laser. This method provides local electron density and temperature simultaneously. With the advances in infrared laser and detection technology, a multichannel system has practiced in many different tokamak devices. Note that the temporal resolution is limited by a duty cycle of high power laser source (∼50 Hz). To overcome this limitation, often few lasers are stacked temporally and the time resolution can be improved. However, the time scale required for study of the MHD phenomena such as disruption and sawtooth crash, could be up to a sub μ-second level. It is imperative to employ diagnostics that can measure a fast phenomena in a required time scale.
Electron density diagnostics that can fulfill the need are interferometry based on the measurement of phase change of electromagnetic waves in the plasma and densitometry based on Faraday rotation angle measurement arising from toroidal magnetic field which is well known. Since both systems are using CW lasers, the time resolution is inherently limited by a detection speed. One disadvantage is that the information has to be transformed into a local value via Abel inversion, since these methods are fundamentally a chordal measurement. However, if the measurement is made on a horizontal plane, the inversion process can be independent of flux surface.
The theory of cyclotron emission is well understood in tokamak plasmas, when the optical depth is deep enough and the supra-thermal emission is absent. Especially, interpretation of Electron Cyclotron Emission (ECE) become complex during current drive experiment at a low plasma density due to expected large runaway electron population. ECE measurement was used to monitor time dependent electron temperature profiles in a tokamak. There are a number of techniques being used in the present tokamaks. Michelson interferometry, based on the measurement of Doppler broadening of the emission, is rather slow due to the mechanical motion of mirror but absolute calibration is possible. Heterodyne method uses a broad band detection system which can be also absolutely calibrated. Recently this method has made a significant engineering advances. 2D (toroidal and poloidal) measurement based on array technology was applied to map the electron temperature on TEXT-U tokamak. However, this may require a good access to project the plasma image.
All these methods will be reviewed and the most suitable systems will be implemented on KSTAR. Since Thomson scattering system can not be used as a tool for the study of temporal behaviors of electrons, ECE and densitometry or interferometry must be combined to fulfill the physics mission of KSTAR.
Explanation:
Since plasma density can vary, the properties of plasma vary depending on that density. ... Hot plasma, which is the type associated with astrophysics, is completely ionized and has a very high plasma density of about one-trillion electrons per cubic centimeter