Advances in ion beam intensity at Sandia National Laboratories
- Sandia National Labs., Albuquerque, NM (United States); and others
In 1993 lithium beam intensities {ge}1 TW/cm{sup 2} were achieved and lithium-driven target experiments at the {approximately}1,400 TW/g level were performed on the Particle Beam Fusion Accelerator II (PBFA II) at Sandia National Laboratories. Hohlraum radiation temperatures of up to 60 eV were achieved using this lithium beam. The 1995 Light-Ion ICF Program milestone of achieving a 100 eV radiation temperature in an ion-driven hohlraum will require a lithium beam intensity of 5 {+-} 1 TW/cm{sup 2} on a 4 mm diameter cylindrical target; this will require both an increase in coupled lithium power and a decrease in total lithium beam divergence. The lithium beam power has been limited to {approximately}5--6 TW by a so-called ``parasitic load.`` This parasitic current loss in the ion diodes has recently been identified as being carried by ions that are accelerated from plasmas that are formed when high voltage electrons are lost to anodes with many monolayers of hydrocarbon surface contamination. Control of anode and cathode plasmas on the SABRE accelerator using RF-discharge cleaning, anode heating, and cryogenic cooling of the cathode have increased the efficiency of the production of lithium current by a factor of 2--3. A new ion diode incorporating glow discharge cleaning and titanium gettering pumps has been installed in PBFA II and will be tested in December, 1994. Anode heaters should be available in January, 1995. Circuit model calculations indicate that one can more than double the coupled lithium ion power on PBFA II by eliminating the parasitic current. LiF source divergence presently dominates the total beam divergence. Progress in lithium beam focal intensity using diode cleaning techniques coupled with an active lithium source is reported.
- Research Organization:
- Sandia National Laboratory
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 182756
- Report Number(s):
- CONF-950612--; ISBN 0-7803-2669-5
- Country of Publication:
- United States
- Language:
- English
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