The Caputo fractional derivative has been one of the most useful operators for modelling non-local behaviours by fractional differential equations. It is defined, for a differentiable function $f(t)$ , by a fractional integral operator applied to the derivative $f^{\prime }(t)$ . We define a new fractional operator by substituting for this $f^{\prime }(t)$ a more general proportional derivative. This new operator can also be written as a Riemann–Liouville integral of a proportional derivative, or in some important special cases as a linear combination of a Riemann–Liouville integral and a Caputo derivative. We then conduct some analysis of the new definition: constructing its inverse operator and Laplace transform, solving some fractional differential equations using it, and linking it with a recently described bivariate Mittag-Leffler function.

An exact solution of partial differential equations provides a lot of information for a model. Since obtaining such answers is generally very difficult or in some cases impossible, having powerful analytical methods in determining them seems very necessary. Unlike numerical methods, these methods have fewer constraints such as stability, convergence, and approximation error. This paper aims to consider the generalized Schamel equation which arises in the modeling of some problems in plasma physics. Fortunately, by applying a new analytical method, a large number of exact solutions to the model are obtained. The structure used in the solutions specified in this method uses Jacobi elliptic functions. In another part of the paper, an effective numerical method, namely the reproducing kernel method is used to approximate the solutions of the equation. Numerical simulations of some acquired exact and approximate solutions are also included. It seems that the employed methods can be considered as effective, powerful, and straightforward methods of studying equations. The methods can also be utilized to investigate other partial differential equations.