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Description
An external RF antenna based cusp free negative H ion source has been designed and developed as shown in figure 1. This source is operated at 10% duty factor and the key experimental result is shown in figure 2. The extracted H- ion beam current is 11 mA with 2 ms pulse duration and 50 Hz repetition rate at 50 kV beam energy. Operation of the H- ion source at high duty factor results in temperature rise in components, which leads to failure of electronic components and vacuum joints of plasma chamber, igniter chamber and burn out of extraction electrodes. In order to keep the operating temperature within limits, water cooling arrangement was designed and incorporated for (i) the 2 MHz RF antenna operating at 80 A RMS at 7 kVAC. (ii) the extraction electrodes, which is operating at maximum voltage of 15 kVDC (iii) the plasma chamber (made of Aluminium Nitride, transparent to RF field with high thermal conductivity) (iv) the Faraday cup for H- ion current measurement. Forced air cooling was used for RF based pulsed igniter, operating at 13.56 MHz and various current stabilizing electrode biasing networks and RF impedance matching networks. Simulations were carried out on the main components and results obtained were satisfactory.
More details of the H- ion source and experimental results will be presented in the manuscript. The content of manuscript will include thermal, vacuum and electrical simulation and experimental results.
Figure 1 link :Experimental test setup of high duty factor RF based negative hydrogen ion source
Full doc document link :Abstract of the Paper in doc
Full PDF document link : Abstract of paper in pdf
Summary
The external RF antenna based negative hydrogen ion source developed indigeneous and tested successfully for 11 mA current at 50 kVDC with 2 ms pulse width at repetition rate of 50 Hz ( 10% duty cycle) and results are presented in the manuscript.
