plasma rocket

8/3/2019 Plasma Rocket

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Submitted by: Ankit Kothari

EL/08/303



To explain the basic principles and working

of plasma rocket plus presenting somefacts.

OBJECTIVE



Rocket propulsion is different from other forms of accelerating an object because the entireacceleration system is contained within the object.

Examples: A runner makes useof

the gro

und to

accelerate; by pushing off of it with his foot. A rocket makes itself go entirely by expelling its

own mass backwards. A rocket does not needanything to push against or pull on. A sailor

thro

wing canno

nballsoff

the backof

a ship isusing the same principle; his craft will accelerateforward with each throw.



Chemical or conventional rocket propulsion- Achemical rocket relies on a highly explosivechemical reaction inside a tube to force fuel

mass downward and the rocket up. NASA's Space Shuttle and the Saturn rockets

used in the Apollo missions are all entirelychemical systems.

Another type is electric propulsion. An electricrocket uses electrical power to accelerate non-volatile propellant out the back of the engine.



THRUST is a measure of how much force therocket can exert.

In order to take off from Earth's surface, a

rocket's thrust must be greater than the force of gravity upon it. In engineering terms, thethrust-to-weight ratio must be greater than one.

SPECIFIC IMPULSE can be thought of as a

rocket's "gas mileage". It measures the amountof speed obtainable from a unit mass of propellant. It is related to the speed of therocket's exhaust.



The Variable Specific ImpulseMagnetoplasma Rocket (VASIMR) is

an electro-magnetic thruster for

spacecraft propulsion. It uses radio waves to ionize a propellant andmagnetic fields to accelerate the

resulting plasma to generate thrust.



One of the main feature of this concept is the

ability to

vary its specif

ic impulse so

that it canbe operated in a mode that maximizespropellant efficiency or a mode that maximizesthrust.



Chang-Diaz has been working on thedevelopment of the VASIMR concept since1979, before founding AD ASTRA in 2005 to

further develop the pro ject.



After many years researching the concept with NASA,

Franklin Chang-Diaz set up the Ad Astra RocketCompany in January 2005 to begin development of theVASIMR engine. Later that year, the company signed aSpace Act Agreement with NASA, and were grantedcontrol of the Advanced Space Propulsion

Laboratory.[6] In this lab, a 50 kW prototype wasconstructed, and underwent testing in a vacuumchamber. Later, a 100 kW version was developed, andthis was followed by a 200 kW prototype



It was announced that the company hadentered into an agreement to test the engine onthe International Space Station, in or before

2013.



The technology uses radio waves to heat gasessuch as hydrogen, argon, and neon, creating hotplasma.

Magneticfields

force the charged plasma

out theback of the engine, producing thrust in the

opposite direction. Due to the high velocity thatthis method achieves, less fuel is required than inconventional engines.

VASIMR has no physical electrodes in contact withthe plasma, prolonging the engine's lifetime andenabling a higher power density than in otherdesigns.



The primary purpose of the first RF coupler isto convert gas into plasma by ionizing it, orknocking an electron loose from each gas atom.

The coupler is shaped in such a way that it canionize gas by launching helical waves throughthe gas. Helicon antennae are a commonmethod of generating plasma.



After the helicon section, the gas is now a "cold

plasma", even though its temperatureapproaches that of the surface of the Sun.

The second RF coupler is called the IonCyclotron Heating (ICH) section. ICH is atechnique used in fusion experiments to heatplasma to temperatures on the order of those inthe Sun's core



It's the most powerful plasma rocket in theworld.

The engine could provide periodic boosts to theISS, which gradually drops in altitude due to atmospheric drag. ISS boosts are currentlyprovided by spacecraft with conventionalthrusters, which consume about 7.5 tonnes of propellant per year.

By cutting this amount to 0.3 tonnes now,VASIMR could save NASA millions of dollars

per year.



Engine Power (kW) Thrust (N)SpecificImpulse (s)

Propellant

PPS-1350 HallThruster(SMART-1)

1.2 0.068 1640 Xe

NSTAR IonEngine(Deep Space1)

2.3 0.092 3300 Xe

NEXT IonEngine 7.7 0.327 4300 Xe

VASIMR ® VX-200

200 5 5000Ar (Optional:D, N, Xe)



In spacecraft propulsion, a Hall thruster is a type of ionthruster in which the propellant is accelerated by anelectric field. Hall thrusters trap electrons in a magneticfield and then use the electrons to ionize propellant,efficiently accelerate the ions to produce thrust, andneutralize the ions.

Hall thrusters are often regarded as a moderate specificimpulse (1600 s) space propulsion technology.

Hall thrusters are able to accelerate their exhaust to speeds between 10²80 km/s (1000-8000 s specificimpulse),



Launched on 24 October 1998.

Although ion engines had been developed at NASAsince the late 1950s, Deep Space 1 was the first use of

io

n engineso

n ano

peratio

nal science spacecraft.

[

achieves a specific impulse of one to three thousandseconds.

Although the engine produces just 92 millinewtons(0.331 ounce-force) thrust at maximum power (2,100Won DS1), the craft achieved high speeds because ionengines thrust continuously for long periods

The engine fired for 678 total days



The ion propulsion system's efficient use of fuel andelectrical power enable modern spacecraft to travelfarther, faster, and cheaper than any other propulsiontechnology currently available.

Ion thrusters expel ions to create thrust and canprovide higher spacecraft top speeds than any otherrocket currently available.



What Is an Ion?

An ion is simply an atom or molecule that iselectrically charged.

IONIZATION-converting neutral atoms into either positive or negative ions.

Plasma is an electrically neutral gas in which allpositive and negative charges--from neutral

atoms, negatively charged electrons, andpositively charged ions--add up to zero.Plasma exists everywhere in nature; it isdesignated as the fourth state of matter



Plasma is the building block for all types of electric propulsion, where electric and/ormagnetic fields are used to push on the

electrically charged ions and electrons to provide thrust.



NASA Evolutionary Xenon Thruster(NEXT) ion thruster in operation. Credit:NASA



Benefits and drawbacks of design

In contrast with usual cyclotron resonanceheating processes, in VASIMR ions areimmediately ejected through the magneticnozzle, before they have time to achievethermalized distribution.

This all

ows

for io

ns to

leave the magneticnozzle with a very narrow energy distribution,and for significantly simplified and compactmagnet arrangement in the engine.



VASIMR does not use electrodes; instead itmagnetically shields plasma from most of thehardware parts, thus eliminating electrode

ero

sio

n - a majo

r so

urceof

wear and tear in io

nengines.

Compared to traditional rocket engines withvery complex plumbing, high performancevalves, actuators and turbopumps, VASIMR eliminates practically all moving parts from itsdesign (apart from minor ones, like gas valves),maximizing its long term durability.



However, some new problems emerge, likeinteraction with strong magnetic fields andthermal management. The relatively large

power at which VASIMR operates generates alot of waste heat, which needs to be channeledaway without creating thermal overload andundue thermal stress on materials used.



A 10- to 20-megawatt VASIMR engine couldpropel human missions to Mars in just 39 days,whereas conventional rockets would take six

months or more. The shorter the trip, the lesstime astronauts would be exposed to spaceradiation, which is a significant hurdle forMars missions. VASIMR could also be adapted

to handle the high payloads of roboticmissions, though at slower speeds than lighterhuman missions.



Although VASIMR is still years away frombeing used in space, Chang-Diaz said that ithas already shown great promise during tests

on Earth. So, it is entirely possible that theengine that will carry the first person to Mars isalready running in a laboratory on Earth.

plasma rocket

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