# ISP of Gridded Ion Thruster.

Thread Starter

#### Lightium

Joined Jun 6, 2012
169
What is the specific impulse of an Ion Thruster? How is it derived?

#### joeyd999

Joined Jun 6, 2011
5,283
Is this cheating (or even correct)?:

Bard said:
Specific impulse is a measure of the efficiency of a rocket engine. It is defined as the total impulse produced by a rocket engine divided by the mass of propellant consumed. The higher the specific impulse, the more efficient the rocket engine.

Ion thrusters are a type of electric propulsion engine that use electricity to accelerate ions to high speeds. The specific impulse of an ion thruster is determined by a number of factors, including the type of propellant used, the electric power input, and the thruster design.

The specific impulse of an ion thruster can be derived using the following equation:

Code snippet
Isp = v_e * g_0 / m_dot

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where:

• Isp is the specific impulse in seconds
• v_e is the exhaust velocity in meters per second
• g_0 is the standard gravitational acceleration on Earth (9.80665 m/s^2)
• m_dot is the mass flow rate of the propellant in kilograms per second
The exhaust velocity of an ion thruster is determined by the electric power input and the thruster design. The mass flow rate of the propellant is determined by the type of propellant used and the operating conditions of the thruster.

Ion thrusters typically have specific impulses in the range of 2,000 to 5,000 seconds. This is much higher than the specific impulse of chemical rockets, which are typically in the range of 200 to 400 seconds. The high specific impulse of ion thrusters makes them well-suited for long-duration missions, such as interplanetary travel.

However, ion thrusters also have some disadvantages. They produce very low thrust, so they require a long time to accelerate a spacecraft to a high speed. They are also relatively expensive to operate.

Despite these disadvantages, ion thrusters are becoming increasingly important for space exploration. They are being used on a number of spacecraft, including the Deep Space 1 and Dawn probes. As technology improves, ion thrusters are likely to become even more common in space exploration.

Thread Starter

#### Lightium

Joined Jun 6, 2012
169
What does g_0 have to do with ion thrusters?

Thread Starter

#### Lightium

Joined Jun 6, 2012
169
That's all I could find myself, was hoping for more light on the subject.

Thread Starter

#### Lightium

Joined Jun 6, 2012
169

#### Danko

Joined Nov 22, 2017
1,835
What is the specific impulse of an Ion Thruster? How is it derived?

Thread Starter

#### Lightium

Joined Jun 6, 2012
169
sqrt(2*mass/Ce)*current*sqrt(voltage)/mass

correct?

Thread Starter

#### Lightium

Joined Jun 6, 2012
169
OK so let me see it's

1/9.8 * sqrt(2 * (Ce/mass) * voltage)