Institute of Laser Engineering, Osaka University
2-6 Yamadaoka, Suita, Osaka, Japan 565-0871
To design an advanced version of inertial fusion (IF) reactor, there are lots of data to be
gathered beforehand into our databases. One of these is a reasonable pulsed ion source, which
is applicable to develop near future energy driver. The other is the reactor wall surface
thickness which is ablated with the intense radiation originated from the IF processes. In this
paper, we report our recent results concerning these two subjects.
In our recent publication [1], we reported source micro-divergence angles of medium mass
ion beams including nitrogen and oxygen. During this work, we found out that the effect of
the beam neutralization on the angle must be investigated to complete the results. A gas-puff
valve was used to put some amount of neutral atoms into the beam propagation region just
behind the cathode. As a test case, the angle of proton beam with hydrogen gas-puff was
measured. About 10% reduction was observed compared with the no gas-puff case. The angle
of the medium-mass ions under the neutralization is now under measurement, which result
will be shown at the meeting. We will also add our recent results with new ion specie.
Examples of their (X-ray, neutron and ion) flux under typical IF reactions are described in
[2-3]. With our present-day technology, we can produce similar orders of these fluxes, in
some cases. As we could produce intense proton beams with our pulsed power machines, and
as we could ask the USA collaborators to irradiate sample targets with the strongest X-ray in
the world, we investigated target ablations with ions and X-rays. Both of the experiments with
proton beams and various sample targets, and the investigations with X-ray are shown here.
The proton beam intensity was up to about 10J/cm 2 , which was high enough to ablate most of
the target materials with one shot. Examples of ablated surface thickness were summarized to
be in the range of up to 30 micron per ion shot for SiC, LiPb and graphite (G650S) samples.
The numerical ablation rates with the MJ level X-ray was 1~7 micron in the case of C, while
the thickness was 0.1~1.5 micron in the case of LiF. The maximum ablation of C was
obtained with the X-ray temperature of 50 ~200 eV, while the maximum ablation of LiF was
obtained with the X-ray temperature of 200~600 eV. The corresponding results of X-ray
experiments with various materials including C, LiF, LiPb, SiC/Si etc. will be shown in [2].
[1] K.Kasuya et al., Laser and Particle Beams, 19, 309-316 (2001).
[2] T.Renk et al., Proc. 1st Int. Workshop on Innovative Concepts for Plasma-Interactive Components in
Fusion, to be published, (2002)
[3] K.Kasuya et al, Proc. 18th IAEA Fusion Conf., CD-ROM Publication, IAEA-CN-77/IFP/04, (2001)
* Supported by the Ministry of Education, Culture, Sports, Science and Technology in Japan/ the Japanese
Society for Promotion of Sciences/ ILE. Osaka University/ and Sandia National Laboratories.
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