Characteristics of a Supersonic Plasma Flow in a Magnetic Nozzle.

Abstract

A high-density and high-speed flowing helium-plasma is produced quasi-steadily (1 ms) by use of a magneto-plasma-dynamic arcjet (MPDA) in various external magnetic field configurations. In a uniform magnetic field configuration, an ion acoustic Mach number M i of the plasma flow is limited to be nearly unity. In a divergent magnetic nozzle configuration, on the other hand, the Mach number increases up to almost 3. The Mach number increases in proportion to the gradient of the magnetic field. Spatial variations of M i are well predicted by an isentropic model of compressible flow. The Mach number decreases in the downstream region due to charge-exchange collisional processes that are caused by a limited pumping capability of surface-recombined neutral gases.

Experimental studies on ion acceleration and stream line detachment in a diverging magnetic field

“…When the ion temperature is much lower than the electron temperature ͑T i Ӷ T e ͒, the electrostatic acceleration becomes important, which is the case for ECR plasmas 23 and helicon plasmas. 27 On the other hand, in cases of magnetoplasma dynamic arcjet plasmas 8 with T i ϳ T e , the gas dynamic effect is important as well.…”

“…In plasma applications, a directed ion flux is used to obtain an efficient momentum exhaust for electric propulsion, e.g., variable specific impulse magnetoplasma rocket, 4 and to achieve high aspect ratios in material processing ͑plasma etching͒. [5][6][7] Diverging magnetic field configurations are often used to obtain a unidirectional flow, [8][9][10][11][12][13] where we may anticipate that the magnetization of ions breaks down in the low magnetic field region. For realizing and controlling the plasma flow, it is important to have the knowledge on flow structure in the low magnetic field region, in which the detachment of ion stream line from the magnetic field line takes place.…”

“…18 The magnetic nozzle effect is analogous to the gas dynamic effect of ordinary fluid, and has been discussed in the conventional acceleration experiments. 8,16 On the other hand, the effect of electrostatic field, which is present in an inhomogeneous plasma, 17,[19][20][21] has not been fully understood so far, because of the difficulty of experiments.…”

Formation of dense, electromagnetically accelerated plasma for laboratory astrophysics

“…Lasers [2], z-pinch discharges [3] and arc channels [4] have been conventionally used to drive the highspeed flow. However, in case of hydro-dynamical acceleration, heating up and expansion processes are inevitable for making the flow, in which the density and the flow speed are gas-dynamically correlated.…”

Влияние Продольного Магнитного Поля На Разлет Эрозионной Лазерной Плазмы В Вакууме И Генерацию Плазмой Собственных Магнитных Полей

“…В плазменных ре-активных двигателях продольное магнитное поле может применяться в качестве магнитного сопла для сжатия и ускорения реактивной плазменной струи [8][9][10][11].…”