High reliability, long lifetime, negative ion source

A negative ion source comprising:

• a plasma chamber containing gas to be ionized;
• a microwave source configured to transmit microwaves to the plasma chamber to ionize the gas into atomic species including hyperthermal neutral atoms;
• a negative ion converter configured to convert the hyperthermal neutral atoms to negative ions;
• and
• a magnetic filter configured to reduce a temperature of an electron density provided between the plasma chamber and the negative ion converter.

A method of producing negative ions, the method comprising:

• providing a gas to be ionized in a plasma chamber;
• transmitting microwaves from a microwave source to the plasma chamber to ionize the gas such that hyperthermal neutral atoms of the gas are produced;
• and
• converting the hyperthermal neutral atoms to negative ions via an interaction with a negative ion source converter.