Re: The Dual-stage 4-grid Ion Thruster


"meiza" <meiza@xxxxxxxx> a écrit dans le message de news:
dnats5$pbb$1@xxxxxxxxxxxxxxxx
> Rémy MERCIER <Rmy.MERCIER.1zqsxn@xxxxxxxxxxxxxxx> wrote:
>
>> This is a new esa' ion thruster, THE 'DS4G' THRUSTER,
>> with isp = 19200s
>> nice!
>> http://www.esa.int/gsp/ACT/propulsion/safe_test_diaries_wk1.htm
>
> Huh, quite a great isp, but where do you need such a thing?
>


Several possible reasons.

1) lower consumable mass. This means higher useful payload ( for a given
launch vehicule )

2) Continuous thrust transfer. Hohman transfer ( aka minimum energy
transfer ) take a lot of time when you go to target far away. Continuous
thrusting reduces this by a big factor.

3) In-space maneuvering. Either attitude correction or orbit changes. When
you want to visit several celestial objects with the same mission ( like a
planet and several of its moons ) or change orbit around a single object.


....... etc


The usual problem with ION thruster is not Too high an Isp ( as if there was
such a thing ) but too low a thrust level level for some applications. It
seems technology is slowly solving this.


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