INTRODUCTION
Any technique used for transmitting a
mass from one point to another in the aerospace environment is called as
propulsion. From past till now, propulsion has been one of the most active fields
of research for many scientists. The main reason for this is the need for
speed, faster trip time, exploration and discovery.
Some of the advanced technologies in
rocket and spacecraft propulsion which are used and to be used in the near
future are given below:
ELECTRIC PROPULSION
Some fundamentally different concept
was introduced for accelerating the propellant mass to overcomes the
limitations of chemical thermodynamic expansion. Into this breech steps the
family of electric propulsion possibilities.
Historically, conceptually and
pragmatically this field has tended to subdivide into three categories:
1)
Electro thermal propulsion
In
this process propellant is heated by some electrical process then expanded
through a suitable nozzle. The arc jet is an electro thermal rocket because it
uses electrical energy to heat a propellant. In this method, an annular arc is
created in the chamber and the propellant is heated to high temperatures as it
interacts with the arc. After the heating, the propellant is expanded through a
conventional nozzle. This type of propulsion takes advantage of using hydrogen
as a propellant, and, like nuclear rockets, experiences a similar performance
gain in specific impulse (up to 1,200 seconds). Unlike nuclear rockets, arc
jets are small, producing little more than several pounds of thrust.
2) Electro static propulsion