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23,000 hours... = 2.6 years

I dont catch the drift... why would you need constant propulsion for 2.6 years? Propel to get to speed, do a 180 and propel to stop. ...and where are they going to put 2.6 years worth of fuel no matter how efficient the thrusters are?

It’s all a matrer of force=mass x accelleration. Lithium is heavier/denser than, say, hydrogen, and if it is being ejected at much higher speeds than a chemical rocket so you don’t need as much of it.

I dont catch the drift... why would you need constant propulsion for 2.6 years? Propel to get to speed, do a 180 and propel to stop. ...and where are they going to put 2.6 years worth of fuel no matter how efficient the thrusters are?

Specific impulse (usually abbreviated as I_sp) is a physical quantity defined as the ratio of change in momentum (impulse) to the mass used, usually fuel. It typically uses units of metres per second (a SI unit) or feet per second (in imperial units). It is equivalent to thrust (a force, in newtons or pounds) per mass flow rate (in kg/s or lbm/s). - Wikipedia

Current ion thrusters (of which this is just a variant) provide only extremely low thrust (think: perfume atomizer or, at best, underarm deodorant spray!) - but can at least do so for a long time, and - get this! - with very good efficiency (= consumption of power to achieve acceleration).

The high efficiency is the selling point! They can't be used to blast off a celestial body (like the Earth or Moon), because their thrust is so weak - but once in orbit (or on an interplanetary trajectory), that gentle thrust can be applied for weeks / months.

For unmanned probes, that's ideal! In the case of crewed missions, you can't afford to wait hours in order to boost speed by a lousy couple of m/s - even if it's 10X more efficient that chemical fuels.

The lithium thruster discussed here is supposedly 25X more-powerful than previous ion thrusters. Probably still not powerful enough for a crewed Earth-Mars mission - but they are hopeful that it can be further improved.

Regards,

Acceleration at 1 g and deceleration of 1g is my guess.