
%\def\proposal{
%\section{Proposal}

\subsection*{Goals of the practicum}
\begin{itemize}
\item Learn basic principles of tokamak operation. 
\item Learn basic instrumentation related to tokamak operation and diagnostics. 
\item Provide hands-on experience at an integrated tokamak facility, including planning, tokamak control, data acquisition and processing, finalization and presentation of experimental results.
\item Provide experience in areas of modern data processing methods, commonly used in today's fusion plasma experiments, in real-life situations.
\item Perform several well defined physics experiments addressing basic plasma phenomena occurring in high temperature tokamak plasmas.
\end{itemize}


\subsection*{Level of the practicum: M.Sc., Ph.D.}


\subsection*{Description of the practicum}
GOLEM (\url{http://golem.fjfi.cvut.cz}) is a small tokamak with a circular poloidal cross-section. Presently it is equipped with 4 basic diagnostics: measurement of loop voltage, plasma current, toroidal magnetic field and plasma radiation in the visible part of the spectrum. Students can measure basic tokamak plasma characteristics on their own. Optional remote control via Internet is available.

\subsection*{Training programmes}
Methodical material and manuals covering specific fields of tokamak physics, technology  and operation have been created providing the necessary basic tokamak-operator training and include a wide range of tasks with increasing levels of complexity, e.g.:
\begin{itemize}
 \item Determination of vacuum chamber parameters: chamber resistivity $R_{ch}$ and inductance $L_{ch}$, that can be deduced from ``vacuum shots``.
\item Basic plasma analysis based on raw data from acquisition systems: loop voltage $U_{loop}$, time derivative of magnetic field $\frac{dB_t}{dt}$, time derivative of both the chamber and plasma current $\frac{dI_{pl+ch}}{dt}$, determining plasma time length $\Delta T_{pl}$, magnetic field $B_t$ and plasma current $I_{pl}$. 
\item Evaluation of basic plasma parameters: central electron temperature $T_e$, edge safety factor $q_e$ and plasma heating power $P_{OH}$.
\item Various types of plasma breakdown studies can be performed: 
	\begin{enumerate}
		\item w/o preionization jet 
		\item effect of parallel or antiparallel orientation of the  toroidal magnetic field $B_t$ with respect to the toroidal electric field $E_t$ 
		\item effect of short ($\approx 3 $ ms) breakdown $E_{BD}$ pulse on plasma formation
		\item optimalization of plasma formation through $\tau_{BD}$ (beakdown) and $\tau_{CD}$ (current drive) trigger delays
		\item effect of working gas pressure $p_{H_2}$ (Paschen's law)
	\end{enumerate}
\item Plasma position studies with the help of a set of Mirnov coils and a linear set of 20 AXUV bolometers.
\item Plasma position stabilisation with an equilibrium magnetic field generated in the vertical magnetic field coils.
\end{itemize}
Besides the tokamak plasma, studies of low temperature plasma of the glow discharge are possible. These can  be created using $H_2$ or $He$ gas in the tokamak chamber.

Advanced mode with the help of the X11 protocol offers the possibility to fully control all the technological aspects of tokamak operation (under appropriate supervision and within pre-programmed specific limits): 
\begin{itemize}
 \item {Vacuum  management:} independent control of  all the vacuum valves, rotary and turbomolecular pumps from the ``cold'' start to the end of the day.
\item {Gas fuelling management:} setiting up working gas pressure in an arbitrary manner.
\item {Chamber conditioning:} cleaning the vessel with the help of baking and glow discharge.
\item {Full control of tokamak energetics:} opportunity to control and generate the electric and magnetic fields separately and thus investigate the behaviour of particular diagnostics within specific conditions. 
\item {Data processing management modification:} for alternative data processing and presentation.
\end{itemize}

\subsection*{Target audience}
The practicum is designed for groups of up to 10 students which can participate in in-situ or remote online/offline mode. Many of the studnets come from the Czech Republic, however, the facility has already several years of experience with Summer school students and special one-time visits. Remote worldwide participation is possible for foreign students. Communication between remote participants and the device is performed after logging into a system, under supervision of an in-situ technician and within pre-described limits, via the following methods:
\begin{itemize}
 \item WWW interface based on HTTP protocol, see figure \ref{fig:remote_control}.
 \item Basic online command line method using the SSH protocol, platform independent (openSSH on Linux or Putty on Windows).
\item Command line method allows instruction looping.
\item It is also possible to create a batch script with a set of a shot instructions for offline processing.
\end{itemize}


\subsection*{Future plans}

Further upgrade of GOLEM is envisioned in the near future - an increase of $B_t$, $I_p$ and the discharge duration. Plasma position stabilization is under consideration and investigation. Basic diagnostics will be supplemented with plasma density measurement (microwave interferometer), $H_{\alpha}$ and X-ray radiation measurement will be installed in the near future. The investigation of plasma edge physics with the help of various probe measurements is planned. The previous version of the GOLEM tokamak, the CASTOR was internationally renowned in this field and the team running the present version can use this long and extensive experience for new setups and experiments.  

Besides this programme there exists a plan to enhance especially the diagnostic system with a compact mass spectrometer, fast camera and other additional diagnostic techniques.  Moreover, a new capacitor bank is planned to greatly prolong the plasma duration. These plans are not currently covered by any application.
%}
